Trichocentrum

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Trichocentrum

Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
(unranked): Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Epidendroideae
Tribe: Maxillariinae
Subtribe: Oncidiinae
Alliance: Trichocentrum
Genus: Trichocentrum
Poepp. & Endl.
Species

About 65, see text
Synonyms

Acoidium Lindl.

Trichocentrum, often abbreviated Trctm in horticulture, is a genus in the orchid family, Orchidaceae. It was described by Stephan Ladislaus Endlicher and Eduard Friedrich Poeppig in 1836; the type species is the Long-spurred Trichocentrum (T. pulchrum). This genus alone makes up the monogeneric Trichocentrum alliance, a quite distinct lineage of the subtribe Oncidiinae

The 65 or so epiphytic species are distributed in damp forests from Mexico to South America, but mostly in Venezuela, Colombia, Ecuador and Peru as well as southern Central America.

Contents

[edit] Description

The pseudobulbs are reduced. The obtuse, fleshy leaves are 9 cm long. They are broadly elliptic to ovate-lanceolate.

The large, showy flowers grow basally on a short peduncle in a single-flowered to few-flowered raceme. They are white, or white covered with maroon dots. The petals and sepals are similar.

The long lip carries a short spur. This feature distinguishes the genus from other Oncidiinae, in which the spur is an extension of the column. The short column has a pair of apical wings on the stigma. The anther often bears minute papillae. There are two waxy pollinia, connected to elongate stipes.

[edit] In horticulture

Trichocentrum species are highly appreciated by orchid growers; some consider them to be among the most beautiful orchids on earth. Culture of members of this genus is highly variable, ranging from the drought-tolerant and easy-to-grow Tiger-like Trichocentrum (T. tigrinum) to smaller and more delicate species.

In cultivation they are subject to rot unless provided with conditions similar to those they experience in the wild. Extensive research into the ecological profiles of individual species may be required to achieve success cultivating them. Many species from Central America apparently endure a prolonged drought for at least part of the year, and have developed succulent leaves to deal with these conditions. Plants may shrivel quite severely without long-lasting injury.

[edit] Systematics

There is disagreement as to the taxonomic status of some species that have recently been moved from Oncidium to Trichocentrum. Morphological characteristics of "typical" trichocentrums, such as being relatively small and squat with a short, few-to-several flowered inflorescence, contrasts sharply with the larger, heavier oncidiums with long, "mule-ear" leaves and showy, branched inflorescences with many flowers, or the "rat-tail" species with terete leaves.

While studies of molecular phylogeny has caused substantial reclassifications[1], it is uncertain whether this new scheme will be widely adopted. Like with many plants, hybridisation might heavily confound cladistic analyses, though the exact extent is unknown. Hybridisation of Trichocentrum with Oncidium has resulted in the hybrid genus ×Trichocidium for example, and similar events in the past would result in unrealistic assessments of relationship based on molecular phylogenetic studies with too limited a scope.

[edit] Species

Dark Trichocentrum, Trichocentrum fuscum
Trichocentrum hoegei parts drawing
Trichocentrum lanceanum
Trichocentrum microchilum
Trichocentrum splendidum
Tiger-like Trichocentrum, Trichocentrum tigrinum

[edit] Footnotes

  1. ^ Williams et al. (2001)

[edit] References

Search Wikimedia Commons Wikimedia Commons has media related to: Trichocentrum
  • Ackerman, J.D. and Chase, M.W. (2001): Notes on the Caribbean orchid flora, 4. More combinations in Trichocentrum and Cyrtochilum. Lindleyana 16(4): 225.
  • Chase, M.W. and Williams, N.H. (2001): Additional transfers to Trichocentrum Poepp. & Endl. and Otoglossum Garay & Dunst. (Orchidaceae: Oncidiinae). Lindleyana 16(3): 218-219.
  • Sandoval-Zapotitla, E. and Terrazas, T. (2001): Leaf anatomy of 16 taxa of the Trichocentrum clade (Orchidaceae: Oncidiinae). Lindleyana 16(2): 81-93.
  • Williams, N.H., Chase, M.W., Fulcher, T., and Whitten, W.M. (2001): Molecular systematics of the Oncidiinae based on evidence from four DNA sequence regions: expanded circumscriptions of Cyrtochilum, Erycina, Otoglossum, and Trichocentrum and a new genus (Orchidaceae). Lindleyana 16(2): 113-139.
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