Phaius Lour.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 92-93

Genus Phaius Lour.

Flora Cochinchinensis: 529 (1790) ; Hooker , Flora of British India 5: 816-818 (1890) [as Phajus ]; Seidenfaden , Opera Botanica 89: 41-49 (1986); Pridgeon et al., Genera Orchidacearum 4: 149-151 (2005). — Type species: Phaius grandifolius Lour.

(For generic synonyms see Pridgeon et al. 2005)

DESCRIPTION

Terrestrial or very rarely epiphytic herbs, in the Flora of Thailand area glabrous except for the

lip and the gynostemium, 40-200 cm tall; stems either short and pseudobulbous or elongate-fusiform and cane-like, several-noded. Basal sheaths few, mostly already partly or entirely decayed and absent at the flowering time. Pseudobulbs (if present) inconspicuous and largely hidden by the petioles of the leaves, close together and the rhizome between the shoots short. Leaves one to few, perennial, plicate, lanceolate-oblong, acute or acuminate, with grooved petioles which sometimes form a pseudostem. Inflorescences unbranched, arising from the base of the leafy shoot or one third to half-way up the stem; peduncles usually with one to few tubular and sheathing sterile bracts; flower-bearing part racemose, erect, mostly few-flowered, floral bracts persistent or caducous. Flowers mostly large and showy, resupinate, often yellow, pink or white, turning blackish-blue when damaged or with age. Ovary not distinct from the pedicel. Sepals and petals similar, free, spreading or campanulate. Lip clearly or obscurely 3-lobed, base free from the gynostemium or united with it only in the lower third, with short or elongate spur, disc often with a callus in the form of keels, side lobes usually more or less erect and enclosing the gynostemium. Gynostemium long, lacking a column-foot, mostly hairy especially on the front side; anther incumbent, operculate, with 8 waxy, clavate pollinia; rostellum entire; stigma in a cavity below the rostellum.

DISTRIBUTION

A genus of c. 40 species distributed mainly in Asia, the Malay Archipelago and the Philippines, with a few species also found in tropical Africa, Madagascar, the Mascarene Islands, N Australia and the south-west Pacific Ocean Islands; five species in Thailand.

ARTIFICIAL KEY TO THE THAI SPECIES OF THE GENUS PHAIUS LOUR.

1. Plants with basal pseudobulbs; inflorescence arising from the base of the leafy shoot or very rarely from the upper part of a cylindric pseudobulb well above the ground (up to 18 cm) ....................................................................................................................... 2

— Plants with cane-like stems; inflorescence arising one third to half-way up the stem ... 4

2. Lip midlobe hardly protruding; flowers spreading, mostly yellow to greenish, lip with orange or brown markings .......................................................... 1. Phaius flavus , p. 93

— Lip midlobe clearly protruding; flowers spreading, subnutant or nutant ..................... 3

3. Sepals and petals 40-58(-63) mm long, with brown-red inner surfaces and white outer surface; lip purple with dark venation and pale pink or white rim; spur 5-8(-9) mm long ......................................................................................... 2. Phaius tankervilleae , p. 94

— Sepals and petals up to 68 mm long, greenish yellow on both sides, lip white with yellow and purple markings in the throat; spur 11-15 mm long ........ 3. Phaius wallichii , p. 97

4. Spur short, to 6 mm long; sepals and petals brownish-yellow or white on the outside, brownish-purple with yellow edges on the inside, lip white or golden yellow with reddish brown markings, apical part nearly pure yellow ............... 4. Phaius indochinensis , p. 98

— Spur 10-18 mm long; sepals and petals pink to light purple or brownish-red ................ ......................................................................................... 5. Phaius mishmensis , p. 100