Orchids of New Guinea

Next Genus: Genus Thrixspermum section Dendrocolla

Genus Thrixspermum

Thrixspermum Lour., Fl. Cochinch. 2 (1790) 519

Synonyms:

Genus Cylindrochilus Thw., Enum. Pl. Zeyl. (1861) 307
Genus Dendrocolla Blume, Bijdr. (1825) 286
Genus Orsidice Rchb.f., Bonplandia 2 (1854) 93
Genus Ridleya (Hook.f.) Pfitzer in Engl. & Prantl, Naturl. Pflanzenfam.
Genus Thylacis Gagnep., Bull. Mus. Hist. Nat. (Paris)

Monopodial epiphytic or sometimes terrestrial plants. Stem short to much elongated. Leaves few to many, arranged in two rows, sheathing at the base, glabrous, deciduous, duplicate, leathery. Inflorescence lateral, a dense, few- to many-flowered raceme, with the flowers opening in succession. Bracts often laterally flattened and then arranged in two rows. Flowers small to rather large, ephemeral, resupinate, usually whitish or yellowish, often with brown spots. Sepals free. Petals free, usually fairly similar to the dorsal sepal but often slightly narrower. Lip without spur, not mobile, concave, in the centre usually with a callus. Column-foot present. Pollinia 4, unequal, arranged in two bodies, solid, caudicles absent, stipe present, viscidium present.

Species present in New Guinea:

Thrixspermum aberrans
Thrixspermum amplexicaule
Thrixspermum brevipes
Thrixspermum collinum
Thrixspermum congestum
Thrixspermum denticulatum
Thrixspermum graeffei
Thrixspermum platystachys
Thrixspermum validum
Thrixspermum warianum
Thrixspermum xantholeucum

Distribution:

Sri Lanka, tropical continental Asia, Malaysia, Indonesia, the Philippines, Papua New Guinea, Australia, Pacific islands, east to Samoa. About 140 species; in New Guinea about 11 species.

Habitat:

Epiphytes in lowland and montane forest, also in plantations and on isolated trees. One species [Thrixspermum amplexicaule (Blume) Rchb.f.] terrestrial among shrubs in swampy vegetation.

Classification:

Subfamily Epidendroideae
Tribe Vandeae
Subtribe Aeridinae
Genus Thrixspermum

Notes:

A genus of monopodial orchids with often rather attractive, but very short-lived flowers. Most are easily recognised by the inflorescences with flattened bracts arranged in two rows, with the flowers appearing one-by-one in succession (section Thrixspermum). Another group of species (section Dendrocolla) lacks such characteristic bracts; they have flowers rather similar to those of Chiloschista, but with an immobile lip. Not very common in cultivation.