Botanical Survey of India | Flora of India

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Trees, shrubs, undershrubs, woody or perennial herbs, rarely annuals, rarely climbing; herbaceous portions more or less usually stellate pubescent; bark usually abounding in mucilage, inner fibrous. Leaves alternate, simple, lobed or digitate; stipules usually present, early caducous. Inflorescences various, usually cymose, sometimes 1-flowered, axillary to terminal. Flowers actinomorphic (except in Helicteres and Kleinhovia), bisexual or unisexual by abortion or polygamous. Sepals 5, usually more or less connate, rarely completely so, valvate. Petals 5 or absent, hypogynous, free or connate at base, contorted or imbricate. Stamens multi- or uniseriate by abortion, many in a column or 5, free; anthers in a head or in a single ring at the apex of the column or distributed on the outside of the tube or arranged along edge of cup or tube with intervening staminodes; anther locules, parallel or divergent, opening lengthwise by a slit or rarely by tenninal pores. Ovary usually 2 - 5-carpellary, rarely unicarpellary, syncarpous or apocarpus; ovules many or few, attached to inner angle of the carpel, anatropous, ascending or horizontal; styles consolidated or as many as locules of ovary. Fruits often 5 valved, loculicidal capsules, woody, chartaceous, sometimes 1 - 6, spreading or spirally twisted follicles or samaras. Seeds few to many, sometimes arillate, occasionally winged; albumen fleshy, thin or absent; cotyledons flat, folded or rolled leafy.

Almost exclusively in tropics and subtropics, and rarely in temperate regions; ca 68 genera and 1100 species; 19 genera and 68 species in India.

Literature. ABEDIN, S. & A. GHAFOOR (1976) Sterculiaceae. In: NASIR, E. & ALI. Fl. W. pakistan 99: 1 - 25. MALICK, K.C. & B. SAFUI (1982). A review of Androecium in Sterculaceae with a key to the genera. Bull. Bot. Surv. India 22: 213 - 216. SHARMA, B.D. (1969). Studies of Indian Pollen grains in relation to taxonomy - Sterculiaceae. Proc. Natl. Inst. Sci. B, 35: 320 - 359. RAO, C.V. (1950). Pollen grains of Sterculiaceae. J. Ind. Bot. Soc. 29: 130 - 131.


1a. Trees or shurbs (except Byttneria herbacea) 2
b. Herbs or undershrubs (except Melochia umbellata, Melhania cannabina, M. futteyporensi, M. hamiltoniana and M. tomentosa 16
2a. Flowers unisexual or polygamous; petals absent 3
b. Flowers bisexual; petals present 8
3a. Leaves scaly beneath; fruits samaras 7. Heritiera
b. Leaves without scales beneath; fruits follicular 4
4a. Follicles opening long before maturity 5
b. Follicles not opening before maturity 6
5a. Androgynophore exserted after anthesis 4. Firmiana
b. Androgynophore remaining within flower after anthesis 14. Pterocymbium
6a. Follicles membranous; seeds usully 2 8. Hildegardia
b. Follicles coriaceous or woody, seeds many 7
7a. Seeds winged 16. Pterygota
b. Seeds without wings 18. Sterculia
8a. Staminal column bears fertile anthers throughout; staminodes absent 3. Eriolaena
b. Staminal column bears fertile anthers at apex; staminodes present 9
9a. Staminal column adnate to gynophore forming stalk, dilated above into a cup; fertile anthers alternating with staminodes towards margin 10
b. Staminal column free from carpels; anthers alternating with staminodes along the margin of the cupular column at its apex 13
10a. Staminal column exserted 17. Reevesia
b. Staminal column remaining inside the flower 11
11a. Flowers actinomorphic; staminal tube narrow, straight; seeds winged 15. Pterospermum
b. Flowers zygomorphic; staminal tube dilated; seeds not winged 12
12a. Large trees; fruits inflated 9. Kleinhovia
b. Usually shrubs, rarely small trees; fruits not inflated 6. Helicteres
13a. Staminodes emarginate; capsules 5-winged 1. Abroma
b. Stamindoes acute; capsules not winged 14
14a. Fertile stamens 5; capsules covered with stiff spines and barbs 2. Byttneria
b. Fertile stamens 10 or 15; capsules tubercled or downy 15
15a. Stamens 15; petals with hooded claw; capsules tubercled 5. Guazuma
b. Stamens 10; petals without hood; capsules downy 10. Leptonychia
16a. Stamens 15 in 5 groups of 3 each; staminodes about 5 times longer than the stamens 13. Pentapetes
b. Stamens 5, solitary; staminodes if present up to twice the length of stamens 17
17a. Staminodes present 11. Melhania
b. Stamindoes absent 18
18a. Ovary 5-carpellary; styles central 12. Melochia
b. Ovary 1-carpellary; styles excentric 19. Waltheria

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