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MORPHOLOGY 
(7) GNETALES 
General character. This group comprises three very distinct genera: 
Ephedra, with about fifty species distributed throughout the arid regions 
of theMediterranean basin and adjacent Asia, and also in the arid regions 
513 
FIGS. 511-516. Ephedra: 511, branches bearing ovulate strobili; 512, branches 
bearing staminate strobili; 513, staminate strobilus, showing staminate "flowers" in 
axils of bracts; 514, ovulate strobilus; 515, an ovulate "flower"; 516, decussating 
bracts of the ovulate strobilus. After WATSON. 
of western North America and South America; Tumboa (often called 
Welwitschia), represented by a single species in the arid districts of 
western South Africa ; and Gnetum, with about fifteen species distrib- 
