Botanical Survey of India | Flora of India

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Small trees, shrubs or lianas. Leaves simple, spirally arranged but often seemingly distichous, petiolate, entire, cuneate or rounded and often slightly oblique at base, pinnately nerved, almost always with circular flat glands on lower surface of leaves especially near base; stipules often early caducous, triangular to subulate. Inflorescence axillary or sometimes epiphyllous, dichotomously branched umbels, glomerules, corymbs or fascicles; lower forks often with bractlets; pedicels articulate near apex. Flowers actinomorphic or zygomorphic, typically 5-merous, rarely 4-merous, bisexual, unisexual, or polygamo-dioecious, hypo-or slightly perigynous. Sepals slightly united at base, imbricate. Petals spathulate, bifid or notched, often inflexed at apex, free or united at base, equal or unequal, creamy white, drying black, open in aestivation. Stamens in a whorl of 5 or 4, subperigynous, all or 3 fertile, free or adnate to bases of sepals; filaments long or short; anthers introrse, dehiscing by longitudinal slits; connectives strongly thickened on dorsal side;pollen 2- to 3-colporate. Disk of 5 intrastaminal epipetalous glands or scales or a 5-glandular or 5-lobed cup. Pistil 2- or 3-carpellary, syncarpous; ovary superior or semi-inferior, pubescent or hispid; styles 2 or 3, free or connate; ovules 2 per locule, pendulous, anatropous, unitegmic, only one developing into a seed; micropyle directed upwards. Fruit a drupe or capsule, oblong, compressed, hispid or pubescent, 1-or 2-locular. Seeds sometimes carunculate, nonendospermous; testa membranous; embryo large; cotyledons thick; radicle small, superior.

S. America, Africa, Asia to Malesia, exclusively in the tropical regions except one genus in extra-tropical Africa; 4 genera and ca 210 species, one genus and 3 species in India.

Literature. LEENHOUTS, P.W. (1957) Dichapetalaceae. In: STEENIS, Fl. Males. Ser. 1.5: 305 - 316. & (1972); 6: 941 - 943, Add. & Corr.

Notes. The most striking morphological feature of the family is frequent concrescence of petiole and peduncle of in florescence which then apparently seems to arise from base of leaf blade.

Pollen grains are colpor(oid)ate, small (longest axis 10 - 17 ), flattened and angulaperturate in Dichapetalum Thouars and spheroidal or somewhat oblong in other genera (Erdtman, G. 1905. Pollen morphology and plant taxonomy).

The family is not reputed to be economically very important. Several species of Dichapetalum are poisonous. Wood is sometimes used as a construction material.

Acetic fluor a strikingly poisonous compound is known to be present in some members (Peters, R. in Endeavour 13: 147. 1954).

Chromosome no. 2n = 20 is reported in Dichapetalum (Mangenot, S. & G. Mangenot in Rev. Cytol. Biol. Veg. 25: 411 - 447. 1962).

The family is distinguished by a series of anatomical characters-stomata have subsidiary cells parallel to pore as in Rubiaceae and occur only on lower surface of leaf; cork is superficial in origin; indumentum is composed solely ofunicellular hairs; absence of glandular hairs; presence of wart-shaped papillae on surface of leaves; frequent occurrence of mucilaginous cells in epidermis, hypodermis and sometimes in ground-tissue of petioles and branches (Metcalfe, C.R. & R. Chalk, 1950. Anatomy of the dicotyledons)

The systematic position of the Dichapetalaceae is controversial. Euphorbiaceous affinity is generally upheld by most recent workers.

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