RHAMNACEAE

Trees, shrubs or lianas, unarmed or thorny; branches spinous or aculeate. rarely cirrhose or tendrillar. Leaves simple, alternate, opposite or subopposite. penninerved or 3-5 -nerved from the base; stipules deciduous or modified into persistent prickles, free or interpetiolar or intra-axillary. Inflorescence axillary or terminal cyme, rarely raceme or panicle or spicate. Flowers minute, regular. bisexual or less commonly polygamous, hypogynous, perigynous or epigynous, intrastaminal disc cup-like, nectariferous, sometimes thickened near and or produced beyond the rim of the cup. Calyx 4 or 5-lobed, rarely 6, usually carinate within down the middle or with a raised line within, the tube generally more or less united with the ovary or disc and usually persistent. Petals 4- 5, sometimes 6, rarely absent, narrowed or clawed at base, cucullate or involute at tip. Stamens 4-5, antipetalous, inserted with petals on edge of disc; filaments filiform, rarely flattened; anthers small, 2 celled or rarely the 2 cells confluent; pollen grains binucleate, tricalporate. Ovary 2-3 -loculed, rarely 4 or 1-loculed; ovules solitary in each cell, anatropous, placentation basal; style simple or divided into as many lobes as locules; stigmas capitate or club-shaped. Fruit a capsule, sometimes winged. Seeds solitary, erect, ovoid, angular or compressed, often arillate; testa coriaceous, crustaceous or membranous, often shining; endosperm scanty, fleshy or horny, rarely lacking; embryo large, straight.

Extensively represented throughout the temperate and tropical regions of the world; 70 genera and ca 1500 species, 12 genera and 57 species in India.

Literature. BHANDARI, M.M. & A.K. BHANSALI (1990) Rhamnaceae. In M.P. Nayar et al,. (eds.) Fasc. Fl. India 20: 26-114. BHANDARI, M.M. & F. PARVEEN (1976) The bearing of pollen morphology on the taxonomy of Rhamnaceae. Proc. Symp. Recent Res. in Plant Sciences Patiala. 22 -23. BROWICZ, K. & J. ZIELINSKI (1977) Rhamnaceae. In K.R Rechinger, Fl. Iranica 125: 1·28. MADAN, D. (1988) Gynoecium ontogenesis in the Rhamnaceae. A comparative study. In P. Leins et al. (eds.). Aspects of Floral development 133·141 . QAISER, M. & S. NAZlMUDDIN (1981) Rhamnaceae. In Fl. Pak. 140: 1-24.

KEY TO THE GENERA

1a. Flowers hypogynous

2

b. Flowers perigynous or epigynous

7

2a. Leaves prominentaly 3 or rarely 5-nerved from the base

3

b. Leaves penninerved

4

3a. Peduncle not fleshy in fruits; fruit a drupe

12. Ziziphus

b. Peduncle fleshy in fruits; fruit dry

5. Hovenia

4a. Secondary nerves numerous, parallel; fruits ellipsoid. 1-2 seeded

1. Berchemia

b. Secondary nerves few, not parallel; fruits globose, 2-4 seeded

5

5a. Disc lining the calyx tube not fleshy

7. Rhamnus

b. Disc lining the calyx tube fleshy

6

6a. Thoms recurved; flowers in axillary fascicles or cymes or umbels

9. Scutia

b. Thoms straight or absent; flowers in terminal or axillary panicles

8. Sageretia

7a. Flowers perigynous

8

b. Flowers epigynous

11

8a. Leaves penninerved

9

b. Leaves 3-5-nerved from the base

10

9a. Fruit indehiscent; seed chamber globose, not continued into the upper appressed appendage

11. Ventilago

b. Fruit dehiscent; seed chamber elongated, continued into the compressed upper appendage

10. Smythea

10a. Fruit winged; epicarp leathery; endocarp woody

6. Paliurus

b. Fruit not winged; epicarp fleshy; endocarp horny or leathery

12. Ziziphus

11a. Tendrils absents; receptacle not prolonged beyond the ovary; fruit girt at base by the persistent calyx tube

2. Colubrina

b. Tendrils present; receptacle prolonged beyond the ovary; fruit crowned with the persistent calyx

12

12a. Inflorescence umbellate; disc entire; fruit wingless

4. Helinus

b. Inflorescence racemose or paniculate; disc lobed; fruit winged.

3. Gouania

List of Lower Taxa