Psilotum
| Psilotum | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Psilotum nudum |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Psilotum | ||||||||||||
| Sw. |
Psilotum is one of the two genera ofthe fork-leaf family (Psilotaceae). Two types are assigned to it .
description
Psilotum species are herbaceous plants that do not develop roots . The subterranean parts of the stems are heavily branched and form gems . The above-ground stems are slender, well defined, dichotomously branching and can be up to 1 m long, but are usually shorter. The leaves are awl-shaped or scale-shaped. They do not show any veins, or they are only weakly pronounced at the base.
The sporangia are sessile or almost sessile, initially spherical, later three-lobed or three-celled. The spores are elliptical and roughly wrinkled.
Systematics and distribution
Psilotum nudum in Hawaii
The genus Psilotum contains only two species and one hybrid :
- Psilotum nudum ( L. ) P.Beauv. : It is distributed worldwide in the tropics and subtropics, with the exception of arid regions. It extends to the southeastern United States , central Japan and South Korea . It is also found on some islands , which areoften remote, especially in the Pacific . In Europe there is an occurrence in southwestern Spain near Algeciras . The sporophyte has the chromosome number 2n = 104.
- Psilotum complanatum Sw. ( Syn .: Psilotum flaccidum Wall. ): It is mainly found in the Pacific region and occurs in Jamaica , Mexico , Central America , South America , Malaysia and on some Pacific islands.
- Psilotum × intermedium W.H.Wagner ( Psilotum complanatum × Psilotum nudum ): This hybrid between the two species has been described by Hawaii .
literature
- Klaus Kubitzki, Karl Ulrich Kramer, Peter S. Green, Erich Götz (Eds.): The Families and Genera of Vascular Plants . Volume 1: Pteridophytes and Gymnosperms . Springer, Berlin / Heidelberg / New York 1990, ISBN 3-540-51794-4 (English).
Individual evidence
- ↑ a b Michael Hassler, Bernd Schmitt: Checklist of Ferns and Lycophytes of the World. ( Memento of the original from November 22, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Version 2.3, as of November 2012, accessed on December 8, 2012.
- ↑ Norman Alan Burges: Psilotum Swartz . In: TG Tutin, NA Burges, AO Chater, JR Edmondson, VH Heywood, DM Moore, DH Valentine, SM Walters, DA Webb (eds.): Flora Europaea . 2nd, revised edition. Volume 1: Psilotaceae to Platanaceae . Cambridge University Press, Cambridge / New York / Melbourne 1993, ISBN 0-521-41007-X , pp. 3 (English, limited preview in Google Book Search).
- ↑ Psilotum nudum at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
Web links
Commons : Psilotum - collection of images, videos and audio files
