Search Results - Gnetae

The plant division Gnetophyta or gnetophytes consists of three genera of woody plants grouped in the gymnosperms. The living Gnetophyta are in the genera Gnetum (family Gnetaceae), Welwitschia (family Welwitschiaceae), and Ephedra (family Ephedraceae). The gnetophytes differ from other gymnosperms (conifers, cycads, and ginkgos) in having vessel elements as in the flowering plants. In some classifications, all three genera are placed in a single order (Gnetales) but in others distributed among three orders, each containing a single family and genus. Most morphological and molecular studies confirm that Gnetum and Welwitschia diverged from each other more recently than from Ephedra.^[1][2][3][4]

The three genera of the gnetophytes are highly specialized to their respective environments, making it difficult to identify homologous characters.^[5] The three extant genera of gnetophytes, a “bizarre and enigmatic” trio^[2], are likely aberrant members of the group, which was diverse and dominant in the Tertiary.^[5] Some synapomorphies of the gnetophytes include enveloping bracts around the ovules and microsporangia, and a micropylar projection of the outer membrane of the ovule that produces a pollination droplet.^[6]

Plants of the genus Ephedra are known as jointfirs because they have long slender branches which bear tiny scale-like leaves at their nodes. Ephedra has been traditionally used as a stimulant, but is a controlled substance today in many jurisdictions because of the risk of harmful or even fatal overdosing.