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6 April, 2016 - 17:26

Gnetophytes are the closest relatives to modern angiosperms, and include three dissimilar genera of plants. Like angiosperms, they have broad leaves. Gnetum species are mostly vines in tropical and subtropical zones. The single species of Welwitschia is an unusual, low-growing plant found in the deserts of Namibia and Angola. It may live for up to 2000 years. The genus Ephedra is represented in North America in dry areas of the southwestern United States and Mexico (Figure 14.23). Ephedras small, scale-like leaves are the source of the compound ephedrine, which is used in medicine as a potent decongestant. Because ephedrine is similar to amphetamines, both in chemical structure and neurological effects, its use is restricted to prescription drugs. Like angiosperms, but unlike other gymnosperms, all gnetophytes possess vessel elements in their xylem.

Figure 14.23 Ephedra viridis, known by the common name Mormon tea, grows in the western United States. (credit: US National Park Service, USDA-NRCS PLANTS Database) 


Watch this BBC video ( the amazing strangeness of Welwitschia.