Helixanthera Lour.

Shrubs or terrestrial root parasites, glabrous or all juvenile parts covered by conchiform hairs. Leaves opposite, subopposite or alternate, sometimes in false whorls, petiolate, ellipticovate, glabrous; venation curvipinnate. Inflorescences centripetal pseudoracemes or spikes; flower buds ossiform, torpedo-shaped, clavate-conical or rounded, narrowly conical or pyriform. Flowers bracteate, ebracteolate, actinomorphic, 4 - 6-merous, glabrous or with conchiform hairs, each flower subtended by a navicular or cupular bract. Calyculus entire or lobed. Petals 4, free or pseudo-sympetalous; lobes patent-reflexed. Stamens 4 - 6, erect, epipetalous; filaments flat, terete or subterete; anthers ellipsoid or ovate-oblong, basifixed, isothecate or anisothecate, elevatilobate with or without sterile apex. Ovary smooth or tubercled; style 4-gonous, articulate or not; stigma capitate, conical or clavate. Fruits smooth or tuberculate. Endosperm horned or hornless, mamillate or not mamillate.

Throughout S & SE. Asia and Africa, ca 25 species; 10 species in India.

KEY TO THE SPECIES

1a. Inflorescences centripetal pseudoracemose

2

b. Inflorescences spicate

6

2a. Flowers 2 or 3 per peduncle; flower buds torpedo-shaped; anthers isothecate

6. Helixanthera ligustrina

b. Flowers more than 10 per peduncle; flower buds ossiform or conical; anthers anisothecate

3

3a. Bracts sigmoid; fruits urceolate in the beginning or even at mature stage

4

b. Bracts ovate or ovate and cucullate; fruits ovoid or broadly elliptic

5

4a. Leaves with 6 or 7 pairs of lateral nerves; flower buds angular, narrowly conical; flowers horizontal on stout racemes, 1.3 - 1.5 cm long; petals more than 1 cm long; ovary subglobose; fruits smooth

3. Helixanthera intermedia

b. Leaves with 3 or 4 pairs of lateral nerves; flower buds terete, ossiform; flowers geniculate, on slender racemes, 6 - 7 mm long; petals less than 7 mm long; ovary urceolate; fruits sparsely tubercled

10. Helixanthera wallichiana

5a. Twigs glabrous throughout; lenticels oblong-elliptic; flower buds ossiform; petals abruptly winged and inflated at base; style distinctly articulated; fruits smooth; endosperm with 4 horns, not mamillate

9. Helixanthera parasitica

b. Twigs cinnamomeous brown due to conchiform hairs when young; lenticels elliptic or circular; flower buds clavate, conical; petals not inflated at base; style not articulated; fruits distinctly tubercled; endosperm hornless, mamillate

7. Helixanthera obtusata

6a. Leaves opposite or subopposite, glabrous throughout; flowers 5 - 6-merous

7

b. Leaves both opposite and alternate or only alternate, covered with conchiform hairs when young; flowers 4-merous

8

7a. Branching pseudo-dichotomous; midrib evanescent towards apex; spikes terminal; flowers 5- merous; bracts lunate; filaments terete; anthers isothecate; pseudocarp ovoid

4. Helixanthera lambertiana

b. Branching lateral; midrib extending up to apex; spike axillary; flowers 6-merous; bracts collar- like; filaments flat; anthers anisothecate; pseudocarp ellipsoid

8. Helixanthera odorata

8a. Flower buds torpedo-shaped; bracts linear-oblong; anthers isothecate; ovary some- what urceolate; fruits ascidiform; endosperm not mamillate

1. Helixanthera coccinea

b. Flower buds clavate-rounded; bracts ovate or suborbicular; anthers anisothecate; ovary depressed-globose; fruits with depressed sides or urceolate; endosperm mamillate

9

9a. Calyculus annular, truncate; filaments flat; style tetragonous; endosperm horned

5. Helixanthera lepidophylla

b. Calyculus obscurely 4-lobed; filaments terete; style terete; endosperm hornless

2. Helixanthera hookeriana

List of Lower Taxa