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How are Ephedra leaves arranged on the stem?
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Gnetophyte
Welwitschia, or tumboa (Welwitschia mirabilis), in Namibia.
The leaves of Ephedra are reduced to small scales, typically about one centimetre long, and are arranged in pairs or in whorls of three around the nodes of the green branchlets. The bases of these leaves form a sheath around the stem at each node. This reduction in leaf surface area is an adaptation to minimize water loss through transpiration, allowing the plant to survive in arid, desert environments where the green stems perform the bulk of photosynthesis.12