Isotria

Isotria medeoloides

Isotria is a genus of the orchid family ( Orchidaceae). It contains only two species that are native to eastern North America.

Description

Isotria are small, herbaceous, perennial plants. They have an underground, thin, hairy rhizome. The roots are unthickened and hairy. The shoot is upright and hollow. He usually carries five leaves in a whorl. These are slightly bluish pruinose, above the middle at the widest, they end pointed.

The terminal inflorescence usually consists of only one, occasionally two flowers. The flowers are 'upside, the color is white, greenish or reddish brown. The three sepals are fused together and narrow lanceolate. The petals are small, face forward and form a corolla tube above the column. The lip is free, three-lobed, the middle lobe with wavy edge. Along the lip run fleshy calluses. The white column is slender at the base, there are two glands, in the end she is wearing the stamen. The opposite to the column axis down curved stamen is like a hood surrounded by tissue of the column ( Klinandrium ), which ends serrated irregular. The stamen has two sides smooth, broad appendage. It contains two chambers in the pollen, which is available free of four pollen grains ( tetrads ). The fruit capsule is upright, it contains numerous spindle-shaped, about 1.2 × 0.2 mm large seeds.

The chromosome number is 2n = 18

Occurrence

Isotria is widespread in eastern North America. There are populated up to 2000 meters altitude. The sites are located in deciduous forests or mixed forests, grow both on wet as on dry soil.

Systematics and botanical history

Isotria is classified within the subfamily Vanilloideae in the tribe Pogonieae. Closely related they are ( also referred to as Cleistesiopsis ) with Pogonia and the North American Cleistes.

Isotria was first described in 1808 by Rafinesque. The name comes from the Greek Isotria ἴσος isos, "equal", and τριάς trias, " number three; threes ", and refers to the three look-alike sepals.

The two species of the genus are Isotria:

Documents

The information in this article come from mainly:

• More Loyal A. Hoff, Michael A. Homoya: Isotria. In: Flora of North America Editorial Committee ( eds.): Flora of North America North of Mexico. 26, Oxford University Press, New York and Oxford 1993 , p 511 ( eFloras.org, accessed on 25/04/2009 ).
• Alec M. Pridgeon, Phillip Cribb, Mark W. Chase and Finn Rasmussen ( ed.): Genera Orchidacearum. Orchidoideae (Part 2). Vanilloideae. 3/2, Oxford University Press, New York and Oxford 2003, ISBN 0-19-850711-9, pp. 291-294.

Furthermore, quoting:

Postgraduate

• List of Orchid Genera

• Orchids
• Orchidaceae