Botanical Survey of India | Flora of India

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Epiphytic semi-parasites on stems and branches of hosts, glabrous, monoecious or dioecious, herbs or shrubs, spreading along branches, di- or trichotomously branched, sometimes pendulous; nodes swollen; internodes terete or compressed or flattened decussately, often longitudinally ridged or striate. Leaves opposite, present and normally developed or rudimentary, entire, unifacial, coriaceous, curvinerved, usually with 3 or 5 visible veins; rudimentary leaves bract-like, up to 1 mm long. Flowers unisexual, usually 4-merous, small, arranged in terminal or axillary and sometimes solitary or fascicled inflorescences, usually in triads, middle flowers of the triad being female, the lateral ones male or vice versa, sometimes all female or all male; bracts small, triangular, in pairs forming boat-shaped cupule subtending each cymule. Male flowers: flattened, 0.5 - 1.5 mm long, 4-merous; perianth shortly tubular at base, lobes triangular, valvate; stamens sessile, epiphyllous; anthers disc-shaped, multi-loculate, opening by pores, sessile and fused to the perianth lobes, pistillode absent. Female flowers: cylindrical, oblong, up to 3 mm long, 4-merous; perianth lobes triangular, sometimes persistent; ovary inferior, adnate to the perianth; ovules not distinct; style short; stigma small, sessile, nipple-shaped, round, flat or capitate. Fruit a berry, narrowly ellipsoid, transparent; perianth lobes rarely persistent as a crown on the fruit.

Europe, throughout Africa, and eastwards to Asia and Australia, about 67 species, 15 species in India of which 4 are endemic.

Literature. DANSER, B. H. (1941). The British-Indian species of Viscum revised and compared with those of South-eastern Asia, Malaysia and Australia. Blumea 4: 260 – 321. RAO, R. S. (1957). A revision of the Indo-Malayan species of Viscum Linn. J. Indian Bot. Soc. 36: 113 - 168.



KEY TO THE SPECIES


1a. Plants dioecious, leafy, leaves lanceolate, to elliptic-lanceolate or obovate-lanceolate; the central flower subtended by a cupule 2. Viscum album
b. Plants monoecious, leafy or leafless; leaf-shape varies; cupule for the central flower present or absent 2
2a. Internodes flattened; leaves few, lanceolate; inflorescence a 3-flowered cyme with the central flower female 10. Viscum mysorense
b. Internodes terete, angular or flattened; leaves few or many, shape varies; inflorescence cymose or subracemose with the central flower either male or female 3
3a. All leafless (rarely leafy in V. ramosissimum); internodes flat, angular or terete; inflorescence sessile 4
b. All leafy; internodes terete; inflorescence sessile or pedunculate 5
4a. Internodes distinctly 4-angled; flowers arranged laterally 3. Viscum angulatum
b. Internodes terete or flattened; flowers arranged laterally or encircling the node 6
5a. Central flower male; leaves cuneate, subtruncate, ovate, obovate or lanceolate 9
b. Central flower female; leaves lanceolate, oblong or ovate-acute 10
6a. Internodes flattened, flattening in a plane at right angles to the preceding one; inflorescences laterally placed 4. Viscum articulatum
b. Internodes terete; inflorescences lateral or around the node 7
7a. Fruits verruculose, subglobose; plants erect 7. Viscum loranthi
b. Fruits smooth, globose to ovoid; plants drooping 8
8a. Branches strong; inflorescence encircling the node; fruits with persistent bracteal cup 8. Viscum malurianum
b. Branches slender; inflorescence lateral; fruits without bracteal cup 13. Viscum ramosissimum
9a. Leaves falcate; young fruits smooth, flask-shaped; inflorescence sessile; intern- odes terete 9. Viscum monoicum
b. Leaves variously shaped; young fruits smooth or warty, globose or oblong; inflorescence sessile or pedunculate; internodes terete or slightly angular 11
10a. Inflorescence sessile; fruits warty, leaves larger, ca 5 x 2 - 3.5 cm 12. Viscum ovalifolium
b. Inflorescence pedunculate; fruits smooth; leaves smaller, 2 - 5 x 0.5 - 2 cm 13
11a. Young fruits warty; internodes longitudinally grooved; leaves ovate, obovate or oblong 6. Viscum heyneanum
b. Young fruits smooth; internodes not grooved; leaves lanceolate, cuneate or subtruncate 12
12a. Inflorescence distinctly pedunculate, at times subracemose; internodes terete throughout; leaves lanceolate, thick; perianth lobes (rarely 3) 2 in male and 3 in female 5. Viscum capitellatum
b. Inflorescence sessile, always cymose; upper internodes slightly angled; leaves cuneate, or subtruncate or suborbicular; perianth lobes 3 in both male and female 15. Viscum trilobatum
13a. Inflorescences subracemose, sometimes with female flowers only; leaves lanceolate to ovate lanceolate; fruit globose; internodes longitudinally grooved 14. Viscum subracemosum
b. Inflorescences cymose or subracemose, heterosexual; leaves of various shapes; fruits globose or oblong; internodes terete or longitudinally grooved 14
14a. Leaves lanceolate; branches slender; inflorescences always 3-flowered 1. Viscum acaciae
b. Leaves ovate or obovate; branches strong, terete; inflorescences up to 5-flowered 11. Viscum orientale


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