FOC_25_Epidendroidea..

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EPIDENDROIDEAE
See the monograph by Seidenfaden (Opera Bot. 83: 1–295. 1985) and the book by H. P. Wood (Dendrobiums. 2006).
Key to sections
1a. Stems with up to 4 internodes near base swollen and fleshy to form distinct fusiform
pseudobulbs, upper part of stem thin and wiry; flowers ephemeral ................................................. 12. D. sect. Crumenata (p. 395)
1b. Stems uniformly thick, fleshy or not, or fusiform, ovoid, or clavate; flowers ephemeral to
long-lived.
2a. Stems uniformly narrow, often wiry, internodes never fleshy or swollen.
3a. Leaves leathery or thinly leathery, dorsiventral, grasslike ........................................................... 1. D. sect. Grastidium (p. 372)
3b. Leaves thick and fleshy, cylindric, subcylindric, or laterally compressed and shortly ensiform.
4a. Leaves laterally compressed and shortly ensiform, 5–6 mm wide; mentum 5–7 mm ................ 13. D. sect. Aporum (p. 396)
4b. Leaves subulate-cylindric or subcylindric, 1.5–3 mm wide; flowers pale yellow, large;
dorsal sepal ca. 12 mm; mentum ca. 20 mm .............................................................................. 14. D. sect. Strongyle (p. 397)
2b. Stems with most internodes fleshy and swollen.
5a. Leaf sheaths, sometimes also leaf blade and inflorescence, with blackish or dark brown
hairs ................................................................................................................................................. 10. D. sect. Formosa (p. 391)
5b. Leaf sheaths, leaf blades, and inflorescences glabrous.
6a. Leaf sheaths insignificant; stems fusiform to clavate, swollen, often angled, sometimes
compressed, with 1–5 ± sheathless leaves clustered at apex; flowers mostly in pendulous,
many-flowered racemes from upper nodes ................................................................................ 2. D. sect. Densiflora (p. 374)
6b. Leaf sheaths distinct, often covering most of internodes; otherwise without above
combination of characters.
7a. Inflorescences several, lateral or subterminal on current year’s stem; flowers several,
small; lip 3-lobed; stems often tufted, often small ............................................................ 11. D. sect. Stachyobium (p. 393)
7b. Inflorescences lateral, usually on leafless stems, pendulous or vertical on stem, most
often with a short peduncle; flowers most often solitary or few, sometimes fascicled,
rarely many on a longer raceme; plants often rather large and robust.
8a. Mid-lobe of lip hairy.
9a. Mid-lobe of lip fringed .......................................................................................................... 7. D. sect. Stuposa (p. 389)
9b. Mid-lobe of lip downy.
10a. Inflorescences many per stem, few flowered; flowers mostly purple or white,
less often yellow; lip usually with expanded mid-lobe ........................................... 3. D. sect. Dendrobium (p. 376)
10b. Inflorescences few, distal, often only 1 per stem, many flowered; flowers
usually yellow; lip expanded .................................................................................... 4. D. sect. Holochrysa (p. 384)
8b. Mid-lobe of lip glabrous.
11a. Flowers usually with a short, saccate mentum.
12a. Inflorescences 1(or 2)-flowered, on leafy stems; dorsal sepal ca. 8 mm;
mid-lobe of lip with distinct keels ....................................................................... 5. D. sect. Distichophylla (p. 388)
12b. Inflorescences 2–6-flowered, on leafless stems; dorsal sepal 13–20 mm;
mid-lobe of lip without keels ...................................................................................... 6. D. sect. Breviflora (p. 388)
11b. Flowers with a long narrow mentum; lip with a long narrow claw.
13a. Lip abruptly broadened from a narrow claw, not forming a spurlike structure
with column foot; mentum pointing away from ovary ............................................ 8. D. sect. Calcarifera (p. 390)
13b. Lip gradually broadened over its length, with a narrow base that forms a spurlike
structure (closed spur) with column foot; mentum held parallel to ovary ................ 9. D. sect. Pedilonum (p. 390)
Key to species
1a. Leaf sheaths insignificant; inflorescence pendulous, arising from leaf axil near stem apex; flowers
yellow or white tinged with yellow, never with green.
2a. Stems 1-leaved, 4-angled.
3a. Inflorescence much longer than stem, many flowered; stems to 10 cm; adaxial surface of lip with only base
and center pubescent, margin glabrous .................................................................................................................... 7. D. lindleyi
3b. Inflorescence shorter or slightly longer than stem, 1–3-flowered; stems 3(–5) cm; entire adaxial surface of
lip pubescent ............................................................................................................................................................ 8. D. jenkinsii
2b. Stems 2–5-leaved, terete or laterally compressed, sometimes with many angles or ridges.
4a. Sepals and petals white; stem with many ridges; leaves usually 1.5–2 cm apart; inflorescence dense; lip
entire, orange ................................................................................................................................................... 12. D. thyrsiflorum
4b. Sepals and petals yellow.