Hopea Roxb., nom. cons.

Resinous trees; trunk buttressed; bark at first smooth, remaining so or at length cracked and flaked or fissured. Leaves small or medium-sized, narrowly oblong with oblique base, coriaceous, often with hairy or pore-like domatia in the axils of lateral nerves; stipules small, linear, fugaceous, stipular scars inconspicuous. Flowers sessile or shortly pedicelled, ebracteate, in axillary and/or terminal, lax panicles of unilateral racemes. Calyx tube very short, during anthesis, adnate to receptacle, lobes densely stellate-tomentose outside, two outer ones longer, ovate, more or less obtuse, thickened, growing out almost immediately after anthesis, ultimately much longer than others, three inner suborbicular, often mucronate, thin along margins. Petals imbricate, oblong, fleshy, densely stellate-tomentose outside. Stamens 10 or 15, rarely numerous in 1 - 3 verticils or irregular, connate at base, falling with the petals; ftlaments subulate, outer-most longer, inner most shorter and sterile; anthers short, medifixed, apiculate portion of connective very thin. Ovary 3-locular, ovules many in 2 rows in axile placentation; styles short, cylindric; stigmas thick. Fruit nut-like, globose, fibrous, 1-seeded, tightly enveloped by the base of accrescent calyx lobes, 2 of which develop into linear wings.

Tropical Asia from India and Sri Lanka eastwards to New Guinea and the Lousiade archipelago, ca 110 species; 11 in India.

KEY TO THE SPECIES

1a. Panicles tomentose

2

b. Panicles glabrous (sometimes minutely puberulous in H. erosa )

5

2a. Leaves glabrous above, pale yellow or silvery (densely minute lepidote) beneath; corolla lobes fimbriate at apex

4. Hopea helferi

b. Leaves not as above, glabrous on both surfaces (paler beneath in H. parviflora); corolla lobes not fimbriate at apex

3

3a. Fruit belly covered with gummy resin; panicle hoary with minute, silky pubescence; anthers suborbicular, mature branchlets hoary

11. Hopea utilis

b. Fruit belly not awered with gummy resin; panicles grey tomentose; anthers ovate or narrowly ellipsoid; mature branchlets glabrous or glaucescent

4

4a. Petioles with a pore and a gland in axils; corolla lobes oblong, falcate, erose, ciliate at tip; leaf bases obtuse or broadly cuneate, unequal

6. Hopea odorata

b. Petioles without a pore or gland in axil; corolla lobes lanceolate, obtuse, dilated and crispate at tip; leaf bases cordate or subcordate, equal

7. Hopea parviflora

5a. Corolla lobes bilobed

2. Hopea erosa

b. Corolla lobes not bilobed; mostly obtuse (sometimes lacerate at the tip as in H. shingkeng)

6

6a. Domatia present in axils of leaf nerves

7

b. Domatia absent in axils of leaf nerves

8

7a. Enlarged wings of fruit 2.5 - 3.2 cm wide, oblong or spathulate; leaf bases acute; lateral nerves of leaves 4 - 5 pairs, obliquely curved

9. Hopea racophloea

b. Enlarged wings of fruit 1.8 - 2 .5 cm wide, oblong or broadly elliptic; leaf bases rounded or cordate, lateral nerves 6 - 10 pairs, arcuate, prolonged, parallel to margins

1. Hopea canarensis

8a. Branchlets densely rufous pubescent; leaves obtuse or subacute at apex; lateral nerves 7 - 10 pairs

8. Hopea ponga

b. Branchlets glabrous; leaves obtuse or caudate-acuminate at apex; lateral nerves not exceeding 9 pairs

9

9a. Calyx lobes broadly lanceolate, acute; corolla lobes obtuse or lacerate at apex; branchlets lenticellate; leaf bases somewhat oblique

10. Hopea shingkeng

b. Calyx lobes ovate, obtuse; corolla lobes obtuse at apex; branchlets not lenticellate

10

10a. Flowers ca 6 mm long; leaves elliptic-oblong to oblong-lanceolate, obtusely acuminate at apex; lateral nerves 6 - 9 pairs

3. Hopea glabra

b. Flowers not exceeding 3 mm long; leaves ovate, caudate-acuminate; lateral nerves 5 - 6 pairs

5. Hopea jacobi

List of Lower Taxa