Isotria
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Isotria is a genus in the family of orchid (Orchidaceae). The only two species are native to eastern North America.
description
Isotria species are small, perennial herbaceous plants . They have an underground, thin, hairy rhizome . The roots are not thickened and hairy. The shoot is erect and hollow. It usually carries five leaves in a whorl. These are slightly bluish, broadest above the middle, they end pointed.
The terminal inflorescence usually contains only one, sometimes two flowers . The flowers are resupinated . The hermaphrodite flowers are zygomorphic and threefold. The color of the bracts is white, greenish or red-brown. The three sepals are not grown together and have a narrow, lanceolate shape. The petals are smaller, point forward and form a flower tube above the column . The lip is free, three-lobed, the middle lobe with a wavy edge. Fleshy calluses run along the lip. The white column is slender, at the base there are two glands, at the end it carries the stamen . The stamen, which is bent down in relation to the column axis, is surrounded by a hood-like tissue of the column (clinandrium), which ends with irregular teeth. The stamen has two smooth, wide appendages on the side. It contains the pollen in two chambers , which is loose in four pollen grains (tetrads).
The capsule fruit stands upright, it contains numerous seeds. The approximately 1.2 × 0.2 millimeter large seeds are spindle-shaped.
The number of chromosomes is 2n = 18.
Locations
Altitudes of up to 2000 meters are populated. The locations are in deciduous forests or mixed forests. They grow on both moist and dry soils .
Systematics and distribution
The genus Isotria belongs to the tribe Pogonieae in the subfamily Vanilloideae within the family Orchidaceae . They are closely related to Pogonia and the North American genus Cleistesiopsis .
The genus Isotria was established in 1808 by Constantine S. Rafinesque-Schmaltz . The generic name Isotria comes from the Greek word ἴσος isos for “equal”, and τριάς trias for “three number; to three ”, and refers to the three identical falls.
Isotria is common in eastern North America.
The two species of the genus Isotria are:
- Isotria medeoloides (Pursh) Raf. : It occurs from southeastern Ontario to Missouri and North Carolina .
- Isotria verticillata (Muehl. Ex Willd.) Raf. : It occurs from southeastern Ontario to the central and eastern United States.
supporting documents
Most of the information in this article comes from:
literature
- Loyal A. Mehrhoff, Michael A. Homoya: Isotria . In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . tape 26 . Oxford University Press, New York and Oxford, S. 511 ( eFloras.org - online with the same text as the printed work).
- Alec M. Pridgeon, Phillip Cribb, Mark W. Chase, Finn Rasmussen (Eds.): Genera Orchidacearum. Orchidoideae (Part 2). Vanilloideae . tape 3/2 . Oxford University Press, New York and Oxford 2003, ISBN 0-19-850711-9 , pp. 291-294 .
Individual evidence
- ↑ a b c Rafaël Govaerts (Ed.): Isotria. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved November 24, 2016.
