Gnetales

Gnetales
	Welwitschia ( Welwitschia mirabilis )
Systematics
without rank:	Streptophyta
Empire :	Plants (Plantae)
Department :	Vascular plants (tracheophyta)
Subdivision :	Seed plants (Spermatophytina)
Class :	Coniferopsida
Order :	Gnetales
Scientific name
	Gnetales
	Luerss.

The Gnetales are an order of the seed plants (Spermatophytina). They are naked animals (gymnosperms) and are currently part of the Coniferopsida due to their molecular genetic characteristics . The order includes 75 species in three genera.

description

Ephedra fragilis

In some characteristics the Gnetophyta resemble the Bedecktsamern (Magnoliophyta), but are probably not an ancestor of the same. The Gnetophyta have a woody sprout that runs underground in Welwitschia . The secondary wood contains vessels . The leaves are opposite or whorled.

The flowers are unisexual, so they have either only female or only male organs. They are grouped into inflorescences . The male flowers have a perianth (perianth). The seeds have two cotyledons .

Systematics

Within the Gnetales there are three families , each with only one genus:

Sea shrub family (Ephedraceae Dum. )
- Genus Meerträubel ( Ephedra Tourn. Ex L. ): 40 species of shrubs in arid regions of South America, the Sahara, the Mediterranean and Asia.

Gnetum gnemon

Family Gnetaceae Lindl.
- Genus Gnetum L .: There are 28 to 40 species. There are lianas , shrubs or small trees in the Neotropic and in the Paleotropic .
Welwitschiagewächse family (Welwitschiaceae Caruel )
- Genus Welwitschia Hook. f. : There is only one type.
  - Welwitschie ( Welwitschia mirabilis Hook. F. ): Namib desert of Namibia and Angola. It forms only two continuously growing, ribbon-shaped leaves and is up to 2000 years old. In 2001, two subspecies were described on the basis of six specimens cultivated in Berlin; this was often cited, but could not be confirmed in field studies. There are still no subspecies.

swell

Christopher J. Earle: Gnetidae Pax ex Prantl 1894. In: The Gymnosperm Database. March 1, 2019, accessed April 9, 2019 .
Peter v. Sengbusch: Information from the University of Hamburg.

Individual evidence

↑ Nicholas Jacobson, Peter Jacobson, Ernst van Jaarsveld, Kathryn Jacobson: Field evidence from Namibia does not support the designation of Angolan and Namibian subspecies of Welwitschia mirabilis Hook. In: Transactions of the Royal Society of South Africa , Volume 69, Issue 3, 2014, pp. 179-186. doi : 10.1080 / 0035919X.2014.950187 .

Web links

Commons : Gnetophyta - collection of images, videos and audio files

[Jacobson2014-1] Nicholas Jacobson, Peter Jacobson, Ernst van Jaarsveld, Kathryn Jacobson: Field evidence from Namibia does not support the designation of Angolan and Namibian subspecies of Welwitschia mirabilis Hook. In: Transactions of the Royal Society of South Africa , Volume 69, Issue 3, 2014, pp. 179-186. doi : 10.1080 / 0035919X.2014.950187 .