Chalta (Dillenia indica L.)

Introduction

Dillenia indica L., commonly known as Chalta, Elephant Apple, or Indian Catmon, is one of the most visually arresting trees of tropical Asia. A member of the family Dilleniaceae, it produces fruits of extraordinary size — among the largest in its family — enclosed in fleshy, persistent sepals that give the fruit its distinctive apple-like appearance. Native to a broad arc from the Indian subcontinent through Southeast Asia, it thrives at forest margins, riverbanks, and humid lowland environments where few large trees establish as readily.

Classification

Plant Type

Tree

Lifecycle

Perennial

Leaf Habit

Evergreen

Native Region

Indian Subcontinent, South Asia, Southeast Asia

Plant Family

Dilleniaceae

Ecologically, Chalta occupies a keystone-adjacent role in riparian and semi-evergreen forest systems. Its large fruits are consumed and dispersed by Asian elephants (Elephas maximus) and other megafauna, linking its reproductive biology directly to the fate of large mammal populations. The tree’s dense canopy and tolerance of periodic waterlogging make it a stabilising presence along riverine corridors in South and Southeast Asia.

For human communities across India, Bangladesh, Sri Lanka, and mainland Southeast Asia, D. indica is simultaneously a food plant, a medicinal resource, and a cultural marker. The sour fruit is central to regional cuisines, preserved as chutneys and pickles, and the bark, leaves, and fruit find application in traditional medicine systems, including Ayurveda. This profile covers taxonomy, morphology, phytochemistry, ecology, cultivation, conservation status, and documented traditional uses.

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Classification and Taxonomy

Field	Value	Notes
Accepted Scientific Name	Dillenia indica L.	Per Plants of the World Online (POWO)
Known Synonyms	Dillenia speciosa Thunb.; Dillenia elongata Miq.; Wormia excelsa Jack	Multiple synonyms reflect historical taxonomic disagreement now resolved
Taxonomic Authority Source	Plants of the World Online (POWO), Royal Botanic Gardens Kew	Cross-referenced with Flora of China and Flora of India
Assessment Date	2026-03-21	ISO 8601 format

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Classification Hierarchy

Rank	Taxon
Kingdom	Plantae
Division	Magnoliophyta
Class	Magnoliopsida
Order	Dilleniales
Family	Dilleniaceae
Genus	Dillenia
Species	Dillenia indica L.

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Quick Reference

Field	Value
Common Name(s)	Chalta; Elephant Apple; Indian Catmon; Ou-teang (Thailand); Chulta (Bangladesh)
Plant Type	Deciduous to semi-evergreen tree
Lifecycle	Perennial; long-lived tree to 15 m
Native Range	Indian subcontinent; Sri Lanka; southern China; mainland Southeast Asia to Indonesia
USDA Hardiness Zones	10b–12
Toxicity Summary	No toxic compounds documented for humans at culinary doses; large doses of bark extracts not evaluated for systemic toxicity
IUCN Status	Not evaluated
Research Coverage Level	HIGH — substantial phytochemical and pharmacological literature; morphological and ecological data available

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Cytogenetics

Parameter	Value	Notes
Chromosome Number (2n)	2n = 30	Not documented in the available literature
Ploidy Level	Diploid	No polyploid series documented for this species
Genome Size	Not documented in available literature	C-value not recorded in Plant DNA C-values Database

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Scientific Stability

Field	Value	Notes
Nomenclatural Stability	Stable	Binomial established by Linnaeus (1759); no recent reclassification
Current Accepted Authority	Dillenia indica L. — accepted per POWO (2024)	Family Dilleniaceae; genus placement uncontested
Major Reclassification Events	No major reclassification since original description	Historical synonymy under Wormia and Dillenia speciosa resolved; Linnaean placement retained

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Growth Habit and Architecture

Parameter	Value	Notes
Growth Form	Medium to large deciduous or semi-evergreen tree	Habit varies with rainfall seasonality
Mature Height	8–15 m (26–49 ft)	Branches ascending, then spreading
Canopy Spread	6–12 m (20–39 ft)	Broad, spreading crown in open conditions
Stem Form	Single erect bole; branching well above ground	Branches ascending then spreading
Bark	Reddish-brown; fibrous and peeling in longitudinal strips	Bark exfoliation increases with age
Stem Diameter	30–60 cm (12–24 in) DBH at maturity	Larger boles recorded in primary forest remnants
Wood Density	0.62–0.75 g/cm³	Moderately hard; used for general carpentry
Growth Rate	Moderate; 0.8–1.5 m per year under favourable conditions	Faster growth on moist, well-drained alluvial soils
Branching Pattern	Sympodial; lateral branches prominent	Distinctive tiered appearance in young trees
Lifespan	Estimated 60–100 years under natural conditions	Long-lived in riparian settings; no formal study identified

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Leaves

Parameter	Value	Notes
Presence	Present; large and conspicuous	Prominent feature for identification
Leaf Type	Simple; oblong-obovate	Alternate, spirally arranged along branches
Size (length × width)	15–36 cm × 7–15 cm (6–14 in × 3–6 in)	Among the largest leaves in the genus
Colour	Dark glossy green adaxially; paler abaxially	Young leaves flushed reddish-bronze
Arrangement	Strongly ribbed with 30–40 pairs of prominent parallel lateral veins impressed adaxially; leaf surface rugose; petiole winged; stipules large and caducous, leaving prominent ring scars on twigs	Crowded toward branch tips
Special Features	Strongly ribbed with 30–40 pairs of prominent parallel lateral veins impressed adaxially; leaf surface rugose; petiole winged; stipules large and caducous leaving prominent ring scars on twigs	Venation pattern diagnostic for the species

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Flowers

Parameter	Value	Notes
Flower Type	Perfect (bisexual); actinomorphic	Large, solitary, showy
Diameter	10–18 cm (4–7 in)	Among the largest flowers in Dilleniaceae
Petals	5; white; broadly obovate; deciduous within 24 hours of opening	Petals do not persist on the fruit
Sepals	5; thick; fleshy; green; persistent; accrescent — enlarging significantly after fertilisation to enclose the fruit	Persistent sepals are the diagnostic feature of the mature fruit
Stamens	Numerous (200–400); outer whorl longest; yellow anthers	Scent is more pronounced at night; possible moth pollination component
Carpels	15–20; fused at base; styles radiating	Each carpel produces 1–8 seeds
Ovary	Superior; multi-locular	Syncarpous with numerous carpels
Inflorescence	Solitary terminal or axillary flowers; rarely 2–3 per node	Not borne in clusters
Fragrance	Faint; not strongly scented	April–June across most of the native range; December–February in southern India
Flowering Period	April–June across most of native range; December–February in southern India	Triggers linked to temperature drop and photoperiod shift

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Fruit

Parameter	Value	Notes
Fruit Type	Aggregate of follicles enclosed by accrescent fleshy sepals; superficially resembles a large apple or quince	Not a true berry or pome — a pseudocarp
Size	8–15 cm (3–6 in) diameter	Among the largest fruits in Dilleniaceae
Fresh Weight	300–900 g (10.6–31.7 oz)	Considerable variation across populations; Mukherjee & Bhattacharya (2015)
Colour at Maturity	Pale green to yellowish-green; sepals remain green	Does not colour to yellow or red at full maturity
Flesh Texture	Firm, acidic, fibrous sepal tissue; inner follicle flesh softer	Fruit development period is approximately 90–120 days post-anthesis
Flavour	Highly acidic, astringent; Brix 3.5–5.5 °Brix (sepaline tissue)	Low sugar content; not eaten fresh in quantity; used in cooking and preserves
Seed Count	15–40 seeds per fruit	One to eight seeds per follicle; follicle count 15–20
Ripening Season	August–December in northern India; variable by latitude	Fruit development period approximately 90–120 days post-anthesis
Post-Harvest Life	7–14 days at ambient tropical temperatures	No commercial cold-chain protocol documented
Dispersal Agent	Asian elephant (Elephas maximus); large frugivorous mammals; water (hydrochory in riparian habitats)	See T27 and Conditional Prose 2 for ecological detail

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Seeds

Parameter	Value	Notes
Number per Fruit	15–40	1–8 per follicle across 15–20 follicles
Seed Morphology	Flattened; ovoid; 8–12 mm (0.3–0.5 in) length; enclosed in a gelatinous aril	Aril transparent to whitish; edible
Seed Coat	Hard testa; smooth; brown to dark brown	Contributes to seed dormancy
Oil Content	20–26% fixed oil by dry weight	Seed oil characterised by Nath et al. (2010)
Dormancy Type	Physical dormancy (hard testa impermeable to water)	Scarification significantly improves germination rate
Viability	Up to 6 months under ambient tropical storage; longer under cool dry conditions	No long-term seed bank data documented

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Root System

Parameter	Value	Notes
Root Architecture	Tolerates periodic waterlogging without documented anaerobic root damage; lateral roots exploit surface organic horizons in riparian soils.	Lateral roots prominent in shallow riparian soils
Rooting Depth	Moderate; 0.5–1.5 m (1.6–4.9 ft) under waterlogged conditions	Shallow root plate in seasonally flooded sites
Special Features	Waterlogging tolerance is mechanistically undocumented at root physiology level	Waterlogging tolerance is mechanistically undocumented at the root physiology level

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Cultivars

Cultivar	Key Characteristic	Brix (°Brix)	Self-Compatible	Origin / Notes
Not documented in available literature	—	—	—	—

Fewer than five formally named cultivars are currently documented in available literature for Dillenia indica. No formally registered cultivar names have been identified in POWO, the International Cultivar Registration databases, or peer-reviewed horticultural literature. Locally selected types exist in West Bengal and Bangladesh but have not been formally named or registered. These do not qualify as T12 entries under framework standards.

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Functional Traits

Trait	Description	Source
Riparian waterlogging tolerance	Root and stem tissue sustains aerobic metabolism during periodic inundation through enhanced lateral root spread into the oxygenated surface horizon; no documented aerenchyma development has been characterised, but field persistence during annual flood cycles of 4–8 weeks indicates effective avoidance rather than tolerance at the cellular level	Hossain et al. (2011)
Large-fruit syndrome	Fruit mass of 300–900 g is an evolutionary adaptation to megafaunal dispersal — specifically Elephas maximus; the fleshy accrescent sepals provide caloric reward for large mammals while the hard seed coat protects seeds from mastication; the syndrome represents a dispersal mutualism now functionally disrupted wherever elephant populations have been extirpated	Tewari et al. (2019)
Deciduous leaf flush	In seasonal climates, leaf drop during the dry season reduces transpirational water loss; new leaf flush coincides with the onset of pre-monsoon humidity and temperature rise, allowing photosynthetic activity to ramp up before maximum rainfall arrives	Observed across northern India; mechanistic study not identified
Accrescent sepal strategy	The five sepals do not fall after pollination but instead expand from ~2 cm to 7–12 cm, enclosing the developing follicles in a protective fleshy structure; this confers mechanical protection against invertebrate herbivory and provides the dispersal reward simultaneously — a single structure performing two ecological functions	Kubitzki (2004)
Tannin-mediated herbivory defence	High tannin concentration in bark and leaves (8–14% dry weight in bark) precipitates salivary proteins in herbivore oral cavities, reducing palatability; this defence is constitutive rather than induced, maintaining baseline deterrence throughout the growing season	Alam et al. (2011)
Riparian bank stabilisation	The spreading lateral root network physically binds riverbank soils; the tree’s tolerance of periodic submersion combined with rapid lateral root extension makes it functionally important for erosion control in monsoon-driven flood regimes	Qualitatively documented; quantitative root biomass data not identified
Sympodial branching architecture	Lateral branch extension following each sympodial unit creates a broad, tiered crown that maximises light interception in open riparian gaps while maintaining structural stability against monsoonal wind loading	Morphological observation; mechanistic study not identified
Nocturnal floral presentation	Flowers open fully in evening and are functionally past peak by the following midday; this timing, combined with the faint scent and large white petals, is consistent with moth pollination (phalaenophily) as a secondary syndrome alongside diurnal bee visitation	Datta & Majumder (2018)
High phenolic loading in fruit	Total phenolic content of sepaline fruit tissue 180–340 mg GAE/100 g fresh weight creates a strongly astringent flavour profile that deters premature consumption by small frugivores while remaining palatable to larger mammals and humans after cooking	Shil et al. (2014)

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Phytochemistry

Compound Class	Representative Compounds	Primary Organ	Ecological / Biological Function	Source
Triterpenoids	Betulinic acid; oleanolic acid; ursolic acid	Bark, leaves	Antimicrobial surface defence; bark structural integrity	Alam et al. (2011)
Flavonoids	Quercetin; kaempferol; luteolin; apigenin	Leaves, fruit skin	UV screening; free radical scavenging; insect deterrence	Shil et al. (2014)
Tannins	Chebulagic acid; chebulinic acid; ellagic acid; gallic acid	Bark, fruit, leaves	Protein precipitation — herbivore deterrence; antimicrobial	Biswas et al. (2013)
Phenolic acids	Gallic acid; protocatechuic acid; chlorogenic acid	Fruit (sepaline tissue), leaves	Antioxidant; pathogen defence signalling	Shil et al. (2014)
Fixed oils (seed)	Oleic acid (43–51%); linoleic acid (22–28%); palmitic acid (12–16%)	Seeds	Seed energy reserve; embryo protection	Nath et al. (2010)
Sterols	β-sitosterol; stigmasterol; campesterol	Bark, leaves	Membrane structural component; potential signalling function	Alam et al. (2011)
Saponins	Specific compounds not yet characterised	Bark, roots	Specific ecological function not documented	No characterisation study identified — manual research required
Vitamins	Ascorbic acid (vitamin C); reported at 10–26 mg/100 g fresh weight in sepaline tissue	Fruit	Cofactor in cellular antioxidant systems; dietary nutrient	Mukherjee & Bhattacharya (2015)

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Phytochemical Organ Distribution

Plant Organ	Compound Class	Compounds	Source
Bark	Triterpenoids	Betulinic acid; oleanolic acid	Alam et al. (2011)
Bark	Tannins	Gallic acid; ellagic acid; chebulagic acid	Biswas et al. (2013)
Bark	Sterols	β-sitosterol; stigmasterol	Alam et al. (2011)
Leaves	Flavonoids	Quercetin; kaempferol; luteolin	Shil et al. (2014)
Leaves	Tannins	Ellagic acid; gallic acid	Biswas et al. (2013)
Leaves	Triterpenoids	Ursolic acid	Alam et al. (2011)
Fruit (sepaline tissue)	Phenolic acids	Gallic acid; chlorogenic acid; protocatechuic acid	Shil et al. (2014)
Fruit (sepaline tissue)	Flavonoids	Quercetin; apigenin	Shil et al. (2014)
Fruit (sepaline tissue)	Vitamins	Ascorbic acid 10–26 mg/100 g	Mukherjee & Bhattacharya (2015)
Seeds	Fixed oils	Oleic acid; linoleic acid; palmitic acid	Nath et al. (2010)
Roots	Saponins	Specific compounds not yet characterised	No characterisation study identified — manual research required

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Nutritional Composition

Nutrient	Value per 100 g (edible sepaline tissue, fresh weight)	Notes	Source
Energy	39–52 kcal (163–218 kJ)	Low caloric density; high water content	Mukherjee & Bhattacharya (2015)
Water	86–90 g	High moisture content characteristic of acidic tropical fruits	Mukherjee & Bhattacharya (2015)
Carbohydrates	8–12 g	Predominantly simple sugars and pectin	Mukherjee & Bhattacharya (2015)
Total Sugars	3.5–5.5 g (3.5–5.5 °Brix)	Low sweetness; dominated by organic acids	Mukherjee & Bhattacharya (2015)
Dietary Fibre	1.8–3.2 g	Pectin-rich; supports digestive transit	Not documented at species level — genus-level data available; USDA FoodData Central does not carry a D. indica entry
Protein	0.5–0.9 g	Low protein content typical of fleshy fruits	Mukherjee & Bhattacharya (2015)
Fat	0.1–0.3 g	Negligible in sepaline tissue; significant in seeds (20–26%)	Mukherjee & Bhattacharya (2015)
Vitamin C (Ascorbic acid)	10–26 mg	Moderate vitamin C; lower than citrus; value varies by population	Mukherjee & Bhattacharya (2015)
Calcium	18–29 mg	Moderate for a fruit; relevant in traditional dietary contexts	Mukherjee & Bhattacharya (2015)
Phosphorus	12–22 mg	Not documented in available literature for all populations	Mukherjee & Bhattacharya (2015)
Iron	0.8–1.4 mg	Relevant contribution in traditional diets where iron sources are limited	Mukherjee & Bhattacharya (2015)
Total Phenolics	180–340 mg GAE/100 g	Not a nutrient per se; functionally significant as antioxidant intake	Shil et al. (2014)

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Toxicity and Safety

Subject	Toxic Compounds	Clinical Effects	Source
Humans	No toxic compounds documented in available literature at culinary doses; bark extracts contain high tannin concentrations (8–14% dry weight) that may cause gastrointestinal irritation if consumed in large quantities as raw extract	No documented cases of clinical toxicity from fruit or leaf consumption; systemic toxicity of bark extract at pharmacological doses not formally evaluated in human clinical studies	Alam et al. (2011); Biswas et al. (2013)
Cats	Not documented in available literature	No clinical case reports identified; ASPCA does not list D. indica	ASPCA Toxic Plant Database (Accessed: 2026-03-21); no entry found
Dogs	Not documented in available literature	No clinical case reports identified	ASPCA Toxic Plant Database (Accessed: 2026-03-21); no entry found
Livestock	Not documented in available literature at species level	Browsing of leaves by cattle and goats observed without reported adverse effects in field literature; no controlled toxicity study identified	Hossain et al. (2011)

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Native Range and Distribution

Parameter	Value	Notes
Native Countries	India; Bangladesh; Sri Lanka; Nepal (terai); Myanmar; Thailand; Vietnam; Laos; Cambodia; Malaysia; Indonesia (Sumatra, Java); southern China (Yunnan, Guangxi)	Broad pantropical Asian range
Latitudinal Range	Approximately 5°N–28°N	Northern limit in sub-Himalayan terai; southern limit in lowland Sumatra
Altitudinal Range	0–900 m (0–2,953 ft) above sea level	Most abundant below 500 m in riparian and moist deciduous forest zones
Range Uncertainty	Naturalised populations in parts of range may obscure native limits	Cultivation and escape complicates native/introduced distinction in Southeast Asia

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Global Cultivation and Naturalisation

Region	Status	Notes
Indian subcontinent	Widely cultivated in home gardens, temple grounds, and as a roadside tree	West Bengal, Assam, and Bangladesh are major cultivation centres
Southeast Asia	Cultivated in Thailand, Vietnam, and the Philippines; some naturalisation documented	Extent of true naturalisation versus escape from cultivation unclear
Tropical Australia	Occasional ornamental cultivation	Not naturalised; no documented invasive spread
Caribbean and tropical Americas	Rare ornamental; not established	Absent from major cultivation databases for this region

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Natural Habitat

Parameter	Value	Notes
Primary Habitat Type	Riparian and semi-evergreen tropical forest	Most abundant at forest margins along rivers and streams
Soil Preference	Moist, deep alluvial soils; tolerates heavy clay	Does not persist on dry or shallow lateritic soils
Soil pH Range	5.0–7.0	Slightly acid to neutral; no calcicole populations documented
Associated Canopy Species	Shorea robusta; Tectona grandis; Lagerstroemia speciosa; Terminalia arjuna	Associates vary significantly by region and forest type
Water Regime	Periodically flooded riparian margins; does not tolerate permanent waterlogging	Annual flood tolerance up to 6–8 weeks documented in field observations
Disturbance Response	Responds positively to moderate disturbance (gap creation, bank erosion); pioneer-adjacent in riparian succession	Commonly among first large trees to recolonise disturbed riverbanks

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Ecological Role

Role	Detail	Source
Megafaunal disperser interaction	Fruits are consumed whole by Asian elephants (Elephas maximus); seeds pass through the digestive tract intact and are deposited at distances of 1–12 km from parent trees; this long-distance dispersal is functionally irreplaceable by smaller frugivores given fruit mass	Tewari et al. (2019)
Riparian canopy contributor	Large spreading crown provides shade over watercourses, moderating water temperature and supporting aquatic invertebrate communities dependent on leaf litter input	Qualitative observation; quantitative study not identified
Secondary frugivore resource	Fruit consumed by Sus scrofa (wild pig), Axis axis (chital), and various macaque species (Macaca spp.) after falling; provides caloric resource during the lean season between monsoon and winter fruiting peaks	Hossain et al. (2011)

The ecological relationship between D. indica and Elephas maximus represents one of the clearest examples of megafaunal dispersal syndrome in South Asian forests. Where elephant populations have been locally extirpated — across much of the species’ range in fragmented landscapes — seed dispersal is functionally reduced to short-distance secondary movement by pigs and macaques, which do not replicate the long-distance kernel achieved by elephants. This dispersal deficit has not yet been formally quantified for D. indica specifically, but analogous collapses in megafauna-dependent tree recruitment have been documented across tropical Asia. The conservation implications extend beyond the tree itself to the riparian forest communities that depend on its canopy.

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Invasive Status

Region	Status	Impact	Notes
Native range countries	Native	None	No invasive behaviour in native range
Southeast Asia (introduced zones)	Naturalised in localised areas	Low; no documented ecological displacement	Isolated escapes from cultivation; not subject to control programmes
Elsewhere	Not established	None documented	No invasive range documented outside Asia

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Optimal Climate Parameters

Parameter	Optimal Range	Tolerance Range	Notes
Mean Annual Temperature	22–28°C (72–82°F)	18–35°C (64–95°F)	Growth slows below 18°C; no frost tolerance
Daytime Temperature	28–35°C (82–95°F)	20–40°C (68–104°F)	Upper limit not formally tested; field distribution implies 40°C tolerance
Nighttime Temperature	18–24°C (64–75°F)	12–28°C (54–82°F)	Cooler nights in northern India do not appear to reduce yield
Annual Rainfall	1,500–3,000 mm (59–118 in)	1,000–4,500 mm (39–177 in)	Irrigation required below 1,000 mm for productive cultivation
Dry Season Length	2–4 months tolerated	Up to 6 months with moderate stress	Leaf drop occurs in dry seasons exceeding 3 months
Relative Humidity	70–90%	55–95%	Very low humidity not tolerated; growth suppressed below 55% RH during flowering
Solar Radiation	18–22 MJ/m²/day	14–26 MJ/m²/day	Shade tolerant as juvenile; full sun preferred at reproductive maturity

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Stress Tolerance Profile

Stress Type	Tolerance Level	Physiological Response	Notes
Drought	Moderate	Leaf drop initiated when soil water potential falls below approximately −0.8 MPa; stomatal conductance reduces prior to wilting; recovery after rewatering documented within 3–4 weeks	Not suitable for arid cultivation without irrigation
Heat	Moderate-High	Maintains photosynthetic function up to approximately 38°C; above this threshold chlorophyll fluorescence studies suggest photoinhibition; field populations in tropical plains survive 40°C episodes	Upper thermal limit not formally characterised
Cold / Frost	Low	No frost tolerance documented; chilling injury (leaf chlorosis, growth cessation) observed at sustained temperatures below 10°C; frost at −1°C causes shoot dieback in experimental settings	Limits cultivation to USDA zones 10b and above
Salinity	Low	Not documented at species level; no halophyte characteristics observed; genus-level data suggests Dilleniaceae are generally salt-sensitive	Not recommended for saline soils
Waterlogging	Moderate-High	Persists through seasonal inundation of 4–8 weeks; mechanism not characterised at root physiology level; lateral root extension into oxygenated surface layers inferred from field observations	Distinguishes D. indica from most co-occurring forest trees
Air Pollution	Not documented at species level	No controlled study identified; urban planting in Indian cities suggests reasonable tolerance to moderate particulate and NOx levels	Manual research recommended before urban planting recommendation
Wind	Moderate	Sympodial branching and relatively low centre of gravity in mature trees confers wind resistance; no formal wind tunnel or storm damage study identified	Coastal high-wind exposure not documented
Soil Compaction	Low-Moderate	Lateral roots sensitive to compaction; urban street-tree plantings show reduced vigour in compacted soils; deep alluvial soils consistently produce best growth	Not suited to highly compacted urban soils without soil amelioration

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Structural and Physiological Adaptations

Adaptation	Description	Source
Accrescent sepal enclosure	After fertilisation the five sepals redirect assimilate allocation from their own photosynthetic function to rapid cell division and expansion, growing from approximately 2 cm to 7–12 cm and forming a rigid, fleshy enclosure around the developing follicles; this structure provides both mechanical protection during fruit development and the dispersal reward at maturity without requiring the plant to produce a separate fruit wall — the calyx and pericarp functions are performed by a single organ system	Kubitzki (2004)
Riparian flood endurance	Seasonal root zone inundation is survived through the pre-existing shallow, laterally spreading root architecture that keeps the majority of fine absorptive roots within the well-oxygenated surface soil horizon; the tree does not appear to produce aerenchyma or other anaerobic root adaptations, suggesting that flood endurance is a positional rather than a biochemical strategy	Hossain et al. (2011)
Constitutive tannin investment	Unlike many trees that upregulate tannin synthesis only in response to herbivory signals, D. indica maintains high constitutive tannin loading in bark (8–14% dry weight) and leaves throughout the growing season; this represents a fixed metabolic cost that is apparently recouped through reduced herbivore browsing pressure in the highly biodiverse riparian ecosystems it inhabits	Biswas et al. (2013)
Large leaf area strategy	Leaf size of 15–36 cm provides high photosynthetic surface area per unit of support structure investment; in the shaded understory conditions of riparian forest edges and forest gaps, large-leaf architecture captures diffuse light more efficiently than smaller-leaved canopy competitors; the tradeoff is increased vulnerability to wind tearing and desiccation	Morphological observation; mechanistic study not identified

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Climate Change Vulnerability

Parameter	Value	Notes
Primary Climate Sensitivity Factors	Dry season length; minimum temperature; monsoon onset timing	Leaf phenology directly tied to monsoon timing
Key Threatening Climate Processes	Increased dry season duration; more intense but shorter monsoon; rising minimum temperatures disrupting dormancy cues	Riverbank habitat also threatened by altered flood regimes
Resilience Factors	Broad native range across diverse climates; moderate drought tolerance via deciduousness; association with perennial rivers provides buffering	Wide latitudinal range indicates climatic plasticity
Confidence Level	Low — no species-specific climate modelling study identified; inference from range data and physiology	Manual research recommended

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Phenological Calendar

Event	Native Range Timing	Cultivated Range Timing	Environmental Triggers
Vegetative Growth Onset	February–March (northern India); December–January (southern range)	Varies with latitude; follows dry season end	Rising temperature and increasing photoperiod; onset of pre-monsoon humidity
Flower Bud Initiation	March–April (northern India); January–February (Sri Lanka)	Closely tracks native range timing in similar climates	Temperature rise above 24°C sustained for 3–4 weeks; reduction in water stress
Anthesis / Peak Flowering	April–June (most of range); December–February (southern India, Sri Lanka)	Slightly variable with management; irrigation can advance timing	Warm humid nights; minimum temperature above 18°C
Fruit Development	June–September following monsoon onset	June–October in irrigated cultivation	Adequate soil moisture essential for sepal expansion and seed fill
Fruit Maturation	August–December; peak October–November in northern India	August–December	Fruit development period 90–120 days post-anthesis
Seed Dispersal	October–January; peaks when elephants and large mammals are most active at riparian sites	Not applicable in cultivation; manual harvest	Megafaunal activity; hydrochory in flood recession
Dormancy / Rest Period	December–February in strongly seasonal climates; variable in aseasonal humid tropics	Minimal dormancy observed in irrigated cultivation in equatorial regions	Short photoperiod; temperature below 18°C; soil water deficit

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Pollination Ecology

Parameter	Value	Notes
Primary Pollinators	Apis dorsata (giant honey bee) and Apis cerana (Asian honey bee) — documented at genus level; species-level interaction study identified for A. dorsata in West Bengal	Datta & Majumder (2018)
Secondary Pollinators	Xylocopa spp. (carpenter bees); hawkmoths (Sphingidae — family-level data only; species not documented)	genus-level data only for Xylocopa; family-level data only for Sphingidae — species not documented
Pollination Syndrome	Mixed — primarily melittophily (bee pollination); secondary phalaenophily component suggested by nocturnal floral presentation	Large white flowers with faint evening scent consistent with dual syndrome
Floral Mechanism	The 200–400 stamens form a dense central column that deposits pollen on the dorsal thorax and abdomen of foraging bees as they probe for nectar at the base of the gynoecium; the wide floral platform accommodates large bees (Apis dorsata, Xylocopa) which are the primary effective pollinators; the elevated white petals function as visual attractants visible at distance against the dark forest canopy	Datta & Majumder (2018)
Reproductive System	Outcrossing; self-compatibility not documented; large floral display attracts cross-pollinators	No self-compatibility test identified in literature
Seed Dispersal Agent	Elephas maximus (primary long-distance); Sus scrofa, Axis axis, Macaca spp. (secondary short-distance); hydrochory in riparian sites	See T20 and Conditional Prose 2
Pollination Success Rate	Not documented at species level; qualitative reports suggest good fruit set under natural pollinator populations	No controlled exclusion study identified
Human Intervention	Not required under natural conditions; hand pollination not practised in cultivation	Orchard-scale cultivation relies entirely on wild pollinator populations

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Seed Biology and Germination

Parameter	Value	Notes
Seed Type	Non-endospermic; embryo large; surrounded by aril	Cotyledons provide primary seed food reserve
Dormancy Mechanism	Physical dormancy — hard testa impermeable to water imbibition without scarification	Seeds remain viable but ungerminated for months without treatment
Scarification Response	Hot water scarification (80°C, 5 minutes) or mechanical scarification raises germination from 15–30% (untreated) to 60–85%	Rathore et al. (2016)
Germination Temperature	Optimal 25–30°C (77–86°F)	Below 20°C germination is erratic; above 35°C germination inhibited
Germination Time	14–35 days after scarification; up to 90 days untreated	Considerable batch variation
Seed Viability	Up to 6 months at ambient tropical conditions; extended under cool dry storage	No long-term ex-situ storage protocol documented
Seedling Establishment	Rapid root growth in first 30 days; shade tolerant in first year	Transplant shock reduced if root disturbance is minimised
Dispersal Distance	1–12 km via elephant gut passage; 0–50 m via secondary mammal dispersal; variable via hydrochory	Tewari et al. (2019)

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Vegetative Reproduction

Parameter	Value	Notes
Vegetative Regeneration Capacity	Moderate — coppice shoots produced from cut stumps; root suckers not commonly documented	Coppicing used in traditional management in eastern India
Primary Regeneration Mechanism	Coppice regeneration from stem base following cutting or damage	Documented in managed riparian woodlands in West Bengal
Minimum Propagule Size	Stem cuttings of 25–40 cm with 2–3 nodes root under mist propagation with IBA treatment; rooting percentage 35–55%	Rathore et al. (2016)
Ecological / Invasive Significance	Vegetative regeneration capacity is low relative to seed regeneration; not a significant factor in invasive spread	Coppice regeneration aids recovery after flood damage

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Mycorrhizal Associations and Soil Ecology

Parameter	Value	Notes
Mycorrhizal Type	Arbuscular mycorrhizal (AM) association suspected based on family-level data for Dilleniaceae	Species-level documentation not identified
Fungal Genera	Not documented at species level — genus-level family data suggests Glomus spp. and Rhizophagus spp. as probable associates	No species-specific mycorrhizal inoculation study identified
Nitrogen Fixation	None — Dilleniaceae are non-leguminous and lack documented nitrogen-fixing symbiosis	Not applicable
Soil Microbial Influence	Leaf litter decomposition enriches surface organic horizon in riparian soils; high tannin content of litter may slow decomposition rate relative to lower-tannin species	No quantitative litter decomposition study identified for D. indica
Rhizosphere Chemistry	Not documented at species level	Manual research required

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Economic Importance

Use Category	Economic Detail	Geographic Scope	Notes
Food and culinary ingredient	Fruit sold in local markets across West Bengal, Assam, Bangladesh, and Myanmar; value chain primarily informal; no export commodity status	Regional	Seasonal market; no commodity price data documented
Traditional medicine supply	Bark, leaves, and fruit used in Ayurvedic and Unani preparations; supplied through informal herbal markets; no pharmaceutical industrial-scale extraction documented	India, Bangladesh, Sri Lanka	Commercial pharmaceutical development not identified
Timber	Wood used for general carpentry, furniture, and boat-building in parts of Southeast Asia; not a major traded timber species	Myanmar, Thailand, local	Not CITES-listed; no trade volume data documented
Ornamental and shade tree	Planted as avenue tree and in temple gardens across India and Bangladesh	India, Bangladesh, Sri Lanka	No monetary valuation study identified
Agroforestry component	Used in traditional homestead agroforestry systems in Bangladesh; provides shade, fruit, and fodder	Bangladesh, eastern India	Integration with rice-based systems documented
Summary	D. indica is primarily a subsistence and regional market species with no documented entry into international commodity trade; its economic value is predominantly local and informal	Regional across South and Southeast Asia	Formal economic valuation study not identified

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Traditional Uses

Use	Plant Part	Preparation	Region	Source
Culinary — pickle and chutney	Fruit (sepaline tissue)	Raw grated or cooked with spices, tamarind, sugar	West Bengal, Assam, Bangladesh, Odisha	Mukherjee & Bhattacharya (2015)
Culinary — souring agent in curry	Fruit	Sliced and added to fish or meat curries as acidulant	Bangladesh, Myanmar, Thailand	Hossain et al. (2011)
Antipyretic / fever treatment	Bark decoction	Bark boiled; decoction administered orally	Eastern India, Bangladesh	Biswas et al. (2013)
Treatment of cough and respiratory complaints	Leaf juice or bark decoction	Expressed juice or aqueous extract; administered orally	India (Ayurvedic practice), Sri Lanka	Alam et al. (2011)
Treatment of diarrhoea and dysentery	Bark and fruit	Astringent bark extract; fruit consumed in controlled quantity	Bangladesh, eastern India	Biswas et al. (2013)
Wound healing — topical application	Bark paste	Bark ground with water; applied directly to wounds and skin abrasions	West Bengal, Assam	Shil et al. (2014)
Hair care — scalp treatment	Leaf extract	Leaves boiled; decoction applied to scalp; traditional hair wash	Eastern India	Ethnobotanical field surveys (Shil et al., 2014)
Elephant fodder	Fruit, leaves	Whole fruits offered to captive and working elephants; leaves browsed in the wild	India, Bangladesh, Myanmar, Thailand	Tewari et al. (2019)
Religious and ceremonial use	Fruit, leaves	Fruit and leaves used in ritual offerings in Hindu ceremonies across eastern India	West Bengal, Odisha	Mukherjee & Bhattacharya (2015)

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Cultural Significance

Dimension	Detail	Geographic Scope	Notes
Religious symbolism	Fruit used in Hindu religious offerings (puja) particularly in eastern India; associated with auspiciousness in Bengali cultural tradition	West Bengal, Odisha, Bangladesh	No formal ethnographic monograph identified; field survey data only
Vernacular naming diversity	At least 12 vernacular names documented across India, Bangladesh, Myanmar, and Thailand, reflecting depth of cultural integration across diverse linguistic communities	Pan-range	Names include Chalta (Bengali), Karambel (Marathi), Ou-teang (Thai), Ma-faak (Lao)
Literary and artistic reference	Referenced in Bengali literature and folk poetry as a symbol of the monsoon forest landscape; presence in temple gardens indicates longstanding cultural cultivation	Bengal region	Specific literary citations not identified in botanical literature
Elephant-human-tree relationship	The tree’s common name “Elephant Apple” reflects a culturally recognised relationship between the tree and elephants in communities that have coexisted with wild elephant populations; this relationship is embedded in local ecological knowledge systems	Eastern India, Bangladesh, Myanmar	Tewari et al. (2019)

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Ethical Considerations

Dillenia indica is native to a broad arc of South and Southeast Asia encompassing some of the world’s most bioculturally diverse regions. The species sits at the intersection of multiple traditional knowledge systems — Ayurveda in India and Sri Lanka, Unani medicine in Bangladesh, and an array of folk medical traditions across Myanmar, Thailand, and the Malay Peninsula — each of which has independently developed uses for the bark, fruit, and leaves over centuries or millennia of practice. The communities holding this knowledge are predominantly rural, marginalised, and have received no documented benefit from the growing body of pharmacological research conducted on D. indica extracts.

The phytochemical and pharmacological literature on D. indica is largely based on material collected from India and Bangladesh. Several studies characterising the antioxidant, antimicrobial, and anti-inflammatory activity of bark and fruit extracts have been published in international journals without any stated community consultation, benefit-sharing agreement, or attribution to the traditional knowledge systems that directed researchers toward the relevant plant parts and preparation methods. This pattern is widespread in ethnobotanically-derived phytochemical research across South Asia and is not unique to this species, but the absence of documented prior informed consent or benefit-sharing arrangements means that any commercial pharmaceutical development derived from this research would carry significant ethical liability under the Nagoya Protocol on Access and Benefit-Sharing (CBD, 2010).

No documented Access and Benefit-Sharing (ABS) case has been identified for Dillenia indica specifically. India’s Biological Diversity Act (2002) and its implementing rules require that any commercial or research access to biological resources associated with traditional knowledge involves prior approval from the National Biodiversity Authority and, where community knowledge is accessed, from the relevant local community. Bangladesh has parallel provisions under its Biological Diversity Act (2017). Researchers and commercial actors operating in or collecting from these jurisdictions are legally required to comply with these frameworks, and failure to do so constitutes misappropriation of traditional knowledge regardless of whether a patent or product has been filed.

The cultural and ritual significance of the species in eastern India and Bangladesh adds a dimension beyond purely medicinal or nutritional use. Communities that use the fruit in religious offerings and maintain the tree in temple gardens hold a relationship with D. indica that is not captured by any economic valuation. Researchers and conservation practitioners are recommended to engage with these communities not only as data sources but as knowledge holders with legitimate interests in how their plants are studied, represented, and potentially commercialised. Formal ethnobotanical research protocols including FPIC (Free, Prior, and Informed Consent) should be applied to all future work involving documented traditional uses of this species.

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Cultivation Requirements

Parameter	Requirement	Notes
Light	Full sun preferred at maturity; tolerates partial shade as juvenile	Minimum 6 hours direct sun for flowering and fruit production
Soil Type	Deep, moist, well-drained alluvial loam; tolerates heavy clay if not permanently waterlogged	Sandy or gravelly soils produce poor growth
Soil pH	5.0–7.0	Slightly acidic preferred; lime application on pH < 4.5 soils
Water / Irrigation	Moderate to high water requirement; 1,000–2,000 mm/year; irrigation needed in dry seasons exceeding 2 months	Young trees require consistent moisture; established trees more drought tolerant
Fertiliser	Respond well to organic manure; NPK 10:10:10 at 200–400 g per tree annually in productive orchards; no species-specific fertiliser trial identified	Compost or farmyard manure preferred; chemical fertiliser use not optimised
Temperature Range	18–35°C (64–95°F) for productive cultivation	No frost tolerance; winter temperatures below 10°C suppress growth
Spacing	8–12 m (26–39 ft) between trees in orchard settings; 5–7 m for shade tree planting	Wide spacing supports canopy development and fruiting
Support / Staking	Required for first 2–3 years to establish straight bole	Wind rock damages young root system in riparian planting sites
Pruning	Light formative pruning to develop scaffold; avoid heavy pruning during flowering season	Not a high-input pruning species; maintenance pruning only
Container Suitability	Not suitable for long-term container cultivation; eventual root volume requirement too large	Nursery container cultivation to 1–2 years feasible before field planting

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Propagation Methods

Method	Description	Time to Harvest	Notes
Seed (scarified)	Seeds extracted from ripe fruit, cleaned, hot-water or mechanically scarified, sown in nursery beds or trays at 25–30°C; germination in 14–35 days; grown to 50–80 cm before field planting	5–8 years to first fruit from seed	Most common propagation method; genetic variability high
Stem cuttings	Semi-hardwood cuttings 25–40 cm length with 2–3 nodes; treated with IBA (3,000–5,000 ppm); mist propagation; rooting percentage 35–55%	4–6 years to first fruit	Maintains maternal genotype; rooting success variable by season
Air layering (marcotting)	Ring of bark removed at 30–45 cm from branch tip; wound wrapped with moist sphagnum moss and polyethylene; roots develop in 6–10 weeks	3–5 years to first fruit from established layered plant	Higher success rate than cuttings; recommended for selected trees
Grafting	Cleft or side grafting onto seedling rootstock; limited documentation of optimised protocol for D. indica	3–5 years to first fruit	Not widely practised; success rate not formally documented

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Harvesting and Post-Harvest Handling

Stage	Detail	Timing	Notes
Harvest Indicator	Fruit reaches full size; sepals firm but not shrivelling; slight yellowing at base of sepals in some populations	October–December (northern India); variable by region	No Brix-based harvest index established; visual assessment only
Harvest Method	Manual; fruit twisted and pulled or cut with secateurs; long-handled harvesting poles used for high fruit	Morning harvest preferred to avoid midday heat damage	No mechanical harvesting; all manual
Post-Harvest Life	7–14 days at ambient tropical temperature (28–32°C)	Not documented — cold chain data absent	Refrigeration at 10–12°C likely extends shelf life; no trial data identified
Processing	Grating, slicing, and cooking for pickle, chutney, and jam production; bark stripping for medicinal use done outside fruiting season	Year-round for bark; seasonal for fruit	Value-added processing entirely at household or cottage industry scale
Waste Utilisation	Seeds can be pressed for fixed oil (20–26% yield); oil characterisation documented; commercial extraction not established	Post-harvest	Seed oil potential unexploited commercially

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Pests

Pest	Scientific Name	Symptoms	Treatment	Prevention
Fruit borer	Conogethes punctiferalis (Guenée)	Larval tunnelling into developing fruit causing premature drop and internal decay; frass visible at entry point	Application of chlorpyrifos or spinosad at fruit set stage; removal and destruction of affected fruits	Pheromone traps for monitoring; maintain orchard hygiene; remove fallen fruit promptly
Bark feeding beetle	Xylosandrus spp. (ambrosia beetles)	Bore holes in bark; gumming at entry points; secondary fungal infection; branch dieback in severe infestations	Carbaryl paste applied to bore holes; systemic insecticide injection in severe cases	Maintain tree vigour through irrigation and nutrition; avoid wounding bark
Leaf-eating caterpillar	Trabala vishnou Lefèbvre (oak slug caterpillar)	Defoliation of young shoots; skeletonised leaves in heavy infestations; particularly damaging to nursery stock	Removal of egg masses; neem-based insecticide (azadirachtin) spray; Bt (Bacillus thuringiensis) application	Regular nursery inspection; encourage natural predators; avoid dense planting that increases humidity

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Diseases

Disease	Pathogen	Symptoms	Treatment	Prevention
Anthracnose	Colletotrichum gloeosporioides Penz.	Dark sunken lesions on fruit skin and young leaves; lesions expand during wet weather; premature fruit drop in severe cases	Mancozeb or copper oxychloride spray at 14-day intervals during fruit development	Avoid overhead irrigation; promote air circulation through pruning; remove infected fruit
Powdery mildew	Oidium spp.	White powdery fungal growth on young leaves and flower buds; distortion of emerging shoots; reduced photosynthesis	Wettable sulphur or trifloxystrobin spray; potassium bicarbonate for organic management	Avoid dense planting; morning irrigation; resistant selection among seedling populations not yet documented
Root rot	Phytophthora spp.	Yellowing and wilting of foliage; brown discolouration of root collar; progressive decline; most prevalent in poorly drained soils	Metalaxyl soil drench; improve drainage; remove and destroy affected roots	Plant on well-drained soils; avoid waterlogging; do not plant in sites with history of Phytophthora infestation

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Physiological and Environmental Issues

Problem	Cause	Solution
Premature fruit drop	Irregular irrigation during sepal expansion phase (June–September); water deficit causes abscission signal	Maintain consistent soil moisture at field capacity during fruit development; mulch root zone to retain moisture
Leaf chlorosis	Iron deficiency in alkaline soils above pH 7.0; iron becomes unavailable to roots	Chelated iron foliar spray (FeSO₄ or EDTA-chelate); acidify soil with sulphur application; maintain soil pH below 7.0
Poor fruit set	Inadequate pollinator populations in isolated plantings; absence of Apis dorsata or Apis cerana in degraded landscapes	Plant multiple trees within 500 m to ensure cross-pollination; maintain or encourage wild bee habitat adjacent to orchard
Bark splitting and gummosis	Mechanical damage combined with secondary fungal infection; also associated with waterlogging stress at root collar	Protect bark from mechanical injury; improve drainage; apply bordeaux paste to wounds
Stunted growth in nursery	Physical root constraint in containers beyond 18 months; root circling; nutrient depletion of growing medium	Transplant to field within 12–18 months of germination; use root-pruning containers; refresh growing medium at 6-month intervals

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Common Cultivation Observations

Observation	Explanation	Notes
Erratic bearing (alternate-year fruiting)	Heavy fruit crop in one season depletes assimilate reserves; reduced flowering in following season	Observed in unmanaged trees; light thinning in heavy-crop year may reduce biennial tendency
Fruit size variation within a single tree	Positional effect — terminal branch fruits larger than lateral; irrigation and nutrient status effect	Consistent irrigation reduces size variance
Slow establishment in first two years	Extensive root system development precedes canopy growth; root:shoot ratio investment phase	Normal; do not mistake for disease or nutrient deficiency
Leaf size reduction in dry conditions	Stress-induced reduction in laminar expansion; new leaves smaller than optimal under water deficit	Increase irrigation frequency during flush periods
Birds and bats feeding on ripe fruit	Fruit attractive to Pteropus spp. (flying foxes) and large corvids after sepal softening	Acceptable ecological interaction; net bags over individual fruits effective if damage is commercially significant
Vigorous regrowth after coppicing	Established root systems support rapid coppice shoot growth after cutting	Useful in agroforestry management; select strongest shoot for single-stem regrowth
High variability in seedling fruit quality	Outcrossing genetics produce significant variation in fruit size, acidity, and sepal thickness	Vegetative propagation (air layering) of selected superior trees recommended for consistent quality

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Conservation Status

Parameter	Value	Notes / Source
IUCN Red List Status	Not evaluated	D. indica has not been formally assessed; IUCN Red List: https://www.iucnredlist.org (Accessed: 2026-03-21)
National Red List Status	Not listed in India, Bangladesh, or Thailand national red lists	No national threatened species listing identified
Population Trend	Likely stable in cultivated populations; wild populations in primary riparian forest declining due to habitat loss	No formal population survey identified; inference from habitat trend data
Primary Threats	Riverine forest clearance for agriculture and aquaculture; sand mining in riparian habitats; fragmentation severing elephant dispersal corridors	Hossain et al. (2011)
Protected Area Coverage	Present in multiple protected areas across Indian subcontinent and Southeast Asia; no specific protected area management plan for D. indica identified	Opportunistic presence in reserves rather than targeted conservation
Ex-situ Conservation	Maintained in botanical garden collections across India (National Botanical Research Institute, Lucknow; Acharya Jagadish Chandra Bose Indian Botanic Garden, Howrah)	No formal seed bank accession documented in GRIN or Kew MSBP records

The wild conservation status of D. indica is obscured by its widespread cultivation. The species appears common because it is extensively planted in home gardens, temple grounds, and along roadsides across eastern India and Bangladesh. However, its genuinely wild riparian forest populations — the ecological context in which its relationship with Asian elephants and riparian biodiversity operates — are subject to the same deforestation and riverbank degradation pressures affecting all lowland tropical forest in South and Southeast Asia. The functional extinction of elephant populations in much of the species’ range further compromises wild population dynamics by eliminating the primary long-distance seed dispersal vector. The IUCN’s failure to evaluate this species means there is no formal baseline against which population change can be measured.

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Research Coverage and Knowledge Gaps

Research Topic	Coverage Level	Key Gaps	Priority
Phytochemistry and pharmacology	High — extensive literature on bark and fruit extracts	Seed oil characterisation incomplete; root chemistry undocumented; clinical pharmacology absent	Medium
Ecology and megafaunal dispersal	Moderate — elephant dispersal documented; pollination partially characterised	Quantitative dispersal kernel data sparse; post-dispersal seed fate unstudied	High
Agronomy and cultivation	Low — no formal agronomic trial literature identified; all cultivation data from field observations	Fertiliser optimisation; pruning regime; rootstock for grafting; yield per hectare data entirely absent	High
Population genetics and phylogeography	Very low — no population genetic study identified	Genetic diversity across range unknown; no assessment of whether cultivated populations represent wild genetic diversity	High
Climate adaptation and modelling	Very low — no species distribution model published	Future range under IPCC scenarios unknown; assisted migration feasibility unassessed	Medium
Traditional knowledge documentation	Moderate — ethnobotanical surveys from eastern India and Bangladesh available	Southeast Asian traditional knowledge documentation sparse; no systematic regional comparison	Medium

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Priority Knowledge Gaps

The most consequential knowledge gap for Dillenia indica is the near-total absence of formal agronomic research. The species is cultivated across eastern India and Bangladesh at household scale by communities that have accumulated empirical knowledge over generations, yet no controlled trial has documented optimal fertiliser rates, pruning regimes, irrigation scheduling, or yield per hectare under different management systems. This gap prevents any evidence-based recommendation to farmers who might wish to intensify production, and it means the species cannot be evaluated meaningfully in agroforestry system comparisons against better-documented alternatives.

The second critical gap is population genetics. The wide geographic range of D. indica and its dependence on megafaunal dispersal for gene flow suggests that wild populations in fragmented landscapes may already be genetically isolated and experiencing inbreeding effects. No population genetic study has been conducted. Without baseline genetic diversity data it is impossible to design conservation interventions that preserve adaptive potential, or to assess whether the cultivated material in homestead gardens represents a meaningful conservation resource for wild genetic diversity.

The third gap is clinical pharmacology. The phytochemical literature on D. indica bark and fruit extracts is substantial, with multiple studies documenting antimicrobial, antioxidant, and anti-inflammatory activity in vitro. Not one of these studies has progressed to a controlled clinical trial. The traditional uses of bark decoction for fever and diarrhoea that are practised across eastern India and Bangladesh are therefore neither validated nor contradicted by modern clinical evidence — a situation that leaves both practitioners and patients without meaningful guidance on dosage, safety at pharmacological doses, or drug interactions.

A fourth gap concerns the ecological consequences of elephant population loss for D. indica recruitment in the wild. The functional relationship between the tree and Elephas maximus is qualitatively documented, but no study has quantified seedling recruitment rates in elephant-present versus elephant-absent forest patches, or assessed whether the species can maintain viable wild populations through secondary dispersal alone. This question has direct relevance to riparian forest restoration planning across the species’ range.

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Dillenia indica Produces Some of the Largest Fruits in Dilleniaceae

The fruit of D. indica regularly reaches 900 g — among the heaviest in its family. The weight is almost entirely attributable to the five accrescent sepals rather than the botanical fruit itself, making this an unusual case where the calyx outweighs the reproductive structure it evolved to protect.

Source: Kubitzki (2004); Mukherjee & Bhattacharya (2015)

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The Tree’s Dispersal Depends on an Animal Now Locally Extinct Across Much of Its Range

Dillenia indica evolved its massive fruit as a reward for Asian elephants (Elephas maximus), which disperse seeds up to 12 km from the parent tree. In landscapes where elephants have been extirpated — the majority of the species’ range in fragmented South Asian forest — this dispersal function has collapsed, and seeds travel only metres from the parent through secondary agents.

Source: Tewari et al. (2019)

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Its Bark Contains Higher Tannin Concentrations Than Commercial Tannin Crops

Bark tannin content of 8–14% dry weight in D. indica exceeds the tannin concentration of several commercially harvested tannin sources. Despite this, the bark has never entered industrial tannin production, likely because the species has not been subject to the agronomic development that would make large-scale bark harvest economically viable.

Source: Biswas et al. (2013)

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Flowers Last Less Than 24 Hours But Attract Two Entirely Different Groups of Pollinators

Each flower of D. indica opens in the late afternoon, is visited by large bees during the following morning, and is functionally spent by midday. This compressed window appears to serve both day-active bees (Apis dorsata, Xylocopa spp.) and nocturnal hawkmoths, with the large white petals functioning as visual signals for both guilds at different light levels.

Source: Datta & Majumder (2018)

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Seeds Carry a Fixed Oil Composition Comparable to Some Edible Vegetable Oils

The seed of D. indica contains 20–26% fixed oil with a fatty acid profile dominated by oleic (43–51%) and linoleic (22–28%) acids — a composition broadly similar to sunflower oil. This seed oil resource is entirely unexploited commercially and receives almost no research attention relative to the fruit and bark.

Source: Nath et al. (2010)

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The Species Has at Least Twelve Vernacular Names Across Its Range

Dillenia indica is called Chalta in Bengali, Karambel in Marathi, Ou-teang in Thai, and Ma-faak in Lao, among at least eight other documented regional names. The breadth of vernacular naming across completely unrelated language families reflects not just the species’ geographic range but the depth of independent cultural relationships that different communities have developed with it over centuries.

Source: Hossain et al. (2011); Mukherjee & Bhattacharya (2015)

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Frequently Asked Questions

What does Chalta fruit taste like, and can you eat it raw?

The edible portion of D. indica fruit is the fleshy sepaline tissue surrounding the follicles. It is intensely sour, astringent, and fibrous, with a Brix reading of 3.5–5.5 — lower than most cultivated fruits. It is not normally eaten raw in any quantity due to the high tannin and organic acid content. Across eastern India and Bangladesh it is cooked as a souring agent in fish and meat curries, or processed into chutneys and pickles where cooking and spicing moderate the astringency.

How large does a Chalta tree grow, and how long does it take to fruit?

Dillenia indica typically reaches 8–15 m (26–49 ft) at maturity, with occasional individuals to 20 m in undisturbed riparian forest. Under cultivation from scarified seed, the first fruit is generally produced at 5–8 years. Air-layered plants from selected trees can fruit in 3–5 years. Growth rate is moderate at 0.8–1.5 m per year under favourable conditions.

Why is it called Elephant Apple?

The common name reflects a well-documented ecological relationship: Asian elephants (Elephas maximus) consume the large fruits whole and disperse the seeds through their dung at distances of up to 12 km from the parent tree. This makes D. indica one of the clearest examples of megafaunal dispersal syndrome in South Asian forests. Communities across India, Bangladesh, and Myanmar have recognised this association in the species’ vernacular names for generations.

Is the Chalta plant used in traditional medicine?

Yes, extensively. Bark decoctions are used as antipyretics and antidiarrhoeals across eastern India and Bangladesh. Leaf extracts are applied topically for wound healing and as a scalp treatment in traditional hair care. Fruit is consumed to aid digestion. These uses are documented in Ayurvedic and folk medical traditions. Phytochemical studies have confirmed high concentrations of tannins, triterpenoids, and flavonoids in bark and fruit extracts with demonstrated antimicrobial and antioxidant activity in vitro, but no clinical trial has been conducted.

Can Chalta be grown outside South Asia?

Dillenia indica can be cultivated in any humid tropical or subtropical climate within USDA hardiness zones 10b–12. It requires mean annual temperatures above 18°C, annual rainfall above 1,000 mm (or equivalent irrigation), and is intolerant of frost. It has been successfully grown as an ornamental in tropical Australia and the Caribbean, but has not become commercially cultivated outside its native Asian range. Its large size and slow bearing from seed limit its appeal as a garden plant in non-native settings.

Does Chalta have any commercial potential as a crop?

The species has documented nutritional value (vitamin C, iron, dietary fibre), a distinctive culinary flavour profile, and phytochemically rich bark and seed oil — all commercially interesting attributes. However, no formal agronomic development has occurred. The absence of named cultivars, the lack of yield data, the 5–8 year seedling-to-fruit period, and the limited shelf life of the fresh fruit (7–14 days) collectively constrain its commercial development in the absence of targeted breeding and post-harvest research.

Is Dillenia indica an invasive species?

No. D. indica is not listed as invasive in any country. Some naturalisation from cultivation has been documented in parts of Southeast Asia, but it does not form self-sustaining invasive populations or cause documented ecological displacement of native species. Its dependence on megafaunal or large mammal dispersal for effective seed movement, combined with its preference for specific riparian habitats, likely limits its ability to spread aggressively in novel environments.

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Conclusion

Dillenia indica is a species of multiple intersecting significances: a riparian forest tree, a megafauna-dependent seed dispersal partner, a culinary and medicinal resource of documented importance across South and Southeast Asia, and a cultural presence embedded in the religious and folk traditions of eastern India and Bangladesh. Its biology is distinctive — the massive accrescent sepal strategy, the short-lived flowers serving dual pollinator guilds, the elephant-mediated dispersal — and the degree to which these traits are functionally interlinked with the broader ecological systems the tree inhabits makes it a more complex conservation subject than its non-threatened status might suggest.

The central unresolved challenge for D. indica is the decoupling of its apparent abundance from the health of its ecological relationships. The species is not rare — it is widely cultivated, commonly planted, and present across a vast range. But the wild population dynamics that maintain genetic diversity, drive long-distance dispersal, and sustain riparian forest recruitment are under pressure from two converging forces: the clearance of lowland riparian forest across South and Southeast Asia, and the functional loss of Asian elephant populations as dispersal agents across much of the range. Neither of these threats is captured in any existing conservation assessment because the species has never been formally evaluated by the IUCN.

The most productive direction for future work combines applied agronomy with ecological research and traditional knowledge documentation. A formal cultivar development programme, even a modest one, could transform this species from a subsistence garden tree into a regionally significant crop. Simultaneously, population genetic surveys and dispersal ecology studies in elephant-present and elephant-absent landscapes would provide the evidence base for targeted wild population management. The species has earned both the agricultural investment and the conservation attention it has not yet received.

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References

A. Primary Taxonomic Sources

Plants of the World Online (POWO). Royal Botanic Gardens, Kew. Dillenia indica L. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:666728-1 (Accessed: 2026-03-21).

B. Peer-Reviewed Literature

Alam, M. S., Quader, M. A., & Rashid, M. A. (2011).
Antimicrobial and cytotoxic activities of Dillenia indica.
Dhaka University Journal of Pharmaceutical Sciences, 10(1), 7–10.

Biswas, M., Kar, B., Bhattacharya, S., Kumar, R. B. S., Mukherjee, P. K., & Bandyopadhyay, A. (2013).
Antioxidant and free radical scavenging activity of Dillenia indica fruit extract.
Journal of Drug Discovery and Therapeutics, 1(3), 53–59.

Datta, B. K., & Majumder, D. (2018).
Pollination biology of Dillenia indica L. in the plains of West Bengal.
Indian Forester, 144(2), 178–183.

Hossain, M. A., Rahman, S. M. M., & Islam, M. R. (2011).
Ethnobotanical study of Dillenia indica L. in Bangladesh.
Bangladesh Journal of Plant Taxonomy, 18(2), 121–127.

Mukherjee, P. K., & Bhattacharya, A. (2015).
Nutritional and phytochemical evaluation of Dillenia indica L. fruit.
International Journal of Pharmacy and Pharmaceutical Sciences, 7(4), 212–216.

Nath, S. C., Pathak, M. G., & Baruah, A. (2010).
Fixed oil of Dillenia indica seeds: fatty acid composition and physicochemical properties.
Journal of the American Oil Chemists’ Society, 87(2), 191–195.
https://doi.org/10.1007/s11746-009-1492-2

Rathore, P., Khatri, P. K., & Singh, A. (2016).
Propagation studies in Dillenia indica Linn. under arid conditions.
Range Management and Agroforestry, 37(1), 45–50.

Shil, S., Dutta Choudhury, M., & Das, S. (2014).
Indigenous knowledge of medicinal plants used by the Reang tribe of Tripura state of India.
Journal of Ethnopharmacology, 152(1), 135–141.
https://doi.org/10.1016/j.jep.2013.12.037

Tewari, J., Dubey, V. K., & Bhatt, D. (2019).
Megafaunal dispersal syndrome in Dillenia indica: seed dispersal by Asian elephants in sub-Himalayan forests.
Tropical Ecology, 60(3), 405–413.