Gnetales

Families of Vascular Plants - Botany 307F
  • Ephedraceae

    • Climbers, or small trees or shrubs of northern hemisphere and South America. Leaves scale-like, evanescent (stem photosynthetic).
    • Ephedra L., the sole genus with 65 species. Some species the source of the alkaloid ephedrine.
  • Gnetaceae

    • Shrubs, climbers, or small trees of the Old and New World tropics. Leaves often broad, resembling those of Angiosperms.
    • Gnetum L., with 28 species. Some species are sources of fiber, edible leaves and seeds.
    • Vinkiella R. Johns., monotypic genus of western New Guinea.
  • Welwitschiaceae

    • Plants consist of a short stout stem and long taproot, the two leaves strap-like, growing through the activity of basal meristems.
    • Welwitschia Hook. f., monotypic genus of the deserts of Namibia and southern Angola.


Friedman & Carmichael (1996)
Mabberley (1997)

 

In the past, the similarities between the reproductive structures of the Gnetales and those of angiosperms have led some authors to suggest the Gnetales as the sister group of the angiosperms. This is the so-called anthophyte theory of the origin of flowering plants. Recently, however, molecular evidence has been obtained indicating that such an origin is unlikely, notably as described in a 1999 commentary by M. W. Frohlich, as well as in the research report by Winter et al. (1999). If interested in these results, you may also wish to look at Frohlich and Parker (2000) in Systematic Botany on "The mostly male theory of flower evolutionary origins: from genes to fossils" (Syst. Bot. 25 (2): 155-170).

Ephedraceae

Ephedra sp., female flowers - New Mexico

Female "flowers" of mormon-tea
(Ephedra sp.), New Mexico

Photo: R. C. Evans 1997 R. C. Evans

Ephedra sp., male flowers - New Mexico

Male "flowers" of mormon-tea
(Ephedra sp.), New Mexico

Photo: R. C. Evans 1997 R. C. Evans

FNA - Ephedraceae

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Gnetaceae (see below for credits and copyright information)

See also living plants in the Botany Department Greenhouse at the University of Toronto.

Gnetum
Photo Gerry Carr, University of Hawaii at Manoa; sketch notes of Botany Department Gnetum specimen (right) © J. Esguerra 2004.

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Welwitschiaceae (see below for credits and copyright information)

See also the living plant in the former Botany Department Greenhouse at the University of Toronto.

Botanik online: Gymnospermae - Welwitschia - male plant

Botanik online: Gymnospermae - Welwitschia - female plant
Welwitschia mirabilis Hook. f. Habit (Messum River,Namibia)

Botanik online: Gymnospermae - Welwitschia - microstrobili

Botanik online: Gymnospermae - Welwitschia - megastrobili
Welwitschia mirabilis Hook. f. Habit (Messum River,Namibia) - (right) female plant with megastrobili


Images Peter v. Sengbusch - b-online@botanik.uni-hamburg.de

Botanik onlinelogo Click HERE for the Botanik online copyright notice.


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