Ampelocissus, Planch.

Key to the species of Ampelocissus View in CoL in Thailand

1. Leaves compound...............................................................................................................................................................................2

- Leaves simple (sometimes lobed)......................................................................................................................................................6

2. Flowers pedicellate.............................................................................................................................................................................3

- Flowers sessile....................................................................................................................................................................................4

3. Abaxial side of the leaflets sparsely hairy with pale arachnoid hairs; ovary hairy ........................................ Ampelocissus araneosa

- Abaxial side of the leaflets densely hairy with pale to cinnamomeus arachnoid hairs; ovary glabrous ...... Ampelocissus divaricata

4. Stems, petioles, petiolules and tendrils glabrous or lightly covered by pale arachnoid hairs; adaxial and abaxial sides of the leaflets glabrous to sparsely covered by pale arachnoid hairs on the veins; inflorescence secondary sparsely covered by a thin layer of ferruginous arachnoid hairs; calyx and disc with no marked lobes.................................................................. Ampelocissus polythyrsa

- Stems, petioles, petiolules and tendrils densely covered by ferruginous arachnoid hairs; adaxial side of the leaflets with conical structures or glabrous except for ferruginous arachnoid hairs on main veins, abaxial side densely covered with ferruginous arachnoid hairs; inflorescence secondary densely covered by a thick layer of ferruginous arachnoid hairs; calyx and disc with marked lobes....................................................................................................................................................................................................5

5. Adaxial side of the leaflets covered by raised conical structures bearing a stiff white hair on top, sparsely covered by ferruginous arachnoid hairs becoming denser on main veins............................................................................................... Ampelocissus elegans

- Adaxial side of the leaflets lack conical structures, glabrous except for ferruginous arachnoid hairs on main veins ......................... ...................................................................................................................................................................... Ampelocissus thyrsiflora

6. Stem and petioles with arachnoid hairs and dark erect glandular hairs.............................................................................................7

- Stem and petioles never with these two hair types together...............................................................................................................9

7. Inflorescence globose, approximately as long as it is wide; pedicels 1–2.5 mm long.............................. Ampelocissus arachnoidea

- Inflorescence pyramidal or elongated, longer than it is wide; pedicels absent or under 1 mm long.................................................8

8. Flowers sessile or with pedicels to 0.4 mm long; inflorescence compact........................................................ Ampelocissus martinii

- Flowers with pedicels 0.5–1 mm long; inflorescence lax ................................................................................ Ampelocissus barbata

9. Stem with scattered minute black prickles; leaves appear concurrently or after the flowers appear........... Ampelocissus harmandii

- Stem without prickles, leaves appear at a time unrelated to the flowers..........................................................................................10

10. Stem and petioles generally glabrous but sometimes with scattered puberulent or arachnoid hairs; leaf blade generally pentagonal or slightly 5-lobate, glabrous except for the abaxial side which has very sparse arachnoid or puberulent hairs on the veins; inflorescence a lax thyrse......................................................................................................................................... Ampelocissus latifolia

- Stem and petioles always hairy with pale arachnoid hairs, leaf blade cordate or oval to 3-lobate, both sides hairy; inflorescence corymbose.........................................................................................................................................................................................11

11. Stem and petioles covered with pale arachnoid hairs becoming floccose, never puberulent; leaf blade 10–17 x 10–14 cm, cordate, adaxial side densely hairy with multicellular flattened hairs 0.2–0.4 mm long and very scattered pale arachnoid hair, abaxial side densely cinnamomeus arachnoid and with multicellular flattened hairs to 0.5 mm long .................................. Ampelocissus rugosa

- Stem and petioles covered with 2 types of hairs: sparse to dense pale arachnoid hairs and minute erect puberulent hairs to 0.1 mm long; leaf blade 3–8 x 2–5 cm, oval to slightly 3-lobate, adaxial side hairy as on stem, abaxial side densely covered with cinnamomeus arachnoid hairs only...................................................................................................................... Ampelocissus changensis