Rhapis

Henderson, Andrew, 2016, A revision of Rhapis (Arecaceae), Phytotaxa 258 (2), pp. 137-152 : 139

Key to the species of Rhapis

1. Prophyll and peduncular bract broad, flattened, completely overlapping, the inflorescences exerted laterally through the bracts on a recurved peduncle; central Laos, eastern Thailand, central Vietnam............................................................................. R. laosensis

- Prophyll and peduncular bract narrow, tubular, not or scarcely overlapping, the inflorescences exerted apically through the bracts on a curved peduncle..........................................................................................................................................................................2

2. Rachillae not filiform, glabrous; staminate and pistillate corollas with well developed, erect, triangular apical lobes, these swollen internally; fruits borne on a swollen, persistent perianth...................................................................................................................3

- Rachillae filiform, usually tomentose, especially the staminate ones; staminate and pistillate corollas with poorly developed, inturned apical lobes, these not swollen internally; fruits borne on a pedicelliform pistillate corolla..................................................5

3. Central segments linear-lanceolate, not acuminate, the apices truncate, toothed; abaxial surface of segments with minute, brown scales; southern China (Guangdong, Hainan, Hong Kong), northern and central Vietnam................................................ R. excelsa

- Central segments lanceolate or elliptic, acuminate, the apices oblique, toothed; abaxial surface of segments without scales.........4

4. Abaxial surface of segments gray indumentose when first exposed; Vietnam (Quang Binh) ..................................... R. kebangensis

- Abaxial surface of segments not indumentose when first exposed; Central Laos, south-central and Peninsular Thailand, western Cambodia, and western Sumatra .......................................................................................................................................... R. subtilis

5. Staminate and pistillate flowers pedicellate.......................................................................................................................................6

- Staminate and pistillate flowers sessile..............................................................................................................................................8

6. Central segments elliptic, multi-veined, acuminate, the apices oblique, toothed, 3.1(1.8–4.2) cm wide; central Laos...... R. evansii

- Central segments narrowly linear, usually 1–2-veined, acuminate, the apices scarcely toothed, 0.6(0.4–1.2) cm wide...................7

7. Segments 7(5–9) per leaf; central segments free almost to the base; northern Vietnam (Hoa Binh, Thanh Hoa)................ R. vidalii

- Segments 15(15–16) per leaf; central segments joined at the base; Vietnam (Nghe An) ......................................... R. puhuongensis

8. Segments 18(13–28) per leaf; central segments narrowly linear, usually 1–2-veined, the apices scarcely toothed; China (Guangxi, Guizhou, Yunnan)................................................................................................................................................................ R. humilis

- Segments 5(2–13) per leaf; central segments lanceolate or elliptic, usually multi-veined, the apices oblique, toothed...................9

9. Ligules scarcely developed; abaxial surface of segments with minute, brown scales; China (Guangxi, Guangdong, Hainan).......... ............................................................................................................................................................................................. R. gracilis

- Ligules acute, solid, more or less persistent, or ligules acute, soon disintegrating; abaxial surface of segments without scales....10

10. Ligules acute, soon disintegrating; central segments free almost to the base, rarely joined at the base, the non-split basal part 0.7(0.1–2.5) cm; northern Vietnam (Ninh Binh, Thanh Hoa) ......................................................................................... R. micrantha

- Ligules acute, solid, more or less persistent; central segments joined at the base, the non-split, basal part 3.3(1.4–5.3) cm long; northern Vietnam (Cao Bang, Ha Giang) and adjacent China (Guangxi)........................................................................... R. robusta