Stutz (19741 suggests that highly plastic C. ledifolius is ancestral to C. montanus 

 and C. intricatus . He believes C. montanus may have evolved to fit its present more 

 mesic habitat by gradual broadening and enlargement of its leaves and development of 

 its deciduous habit. He also theorizes that Ceraocarpus intricatus evolved to fit a 

 more xeric habitat by developing smaller, narrower leaves, which it retains even when 

 growing in more moist riparian conditions. 



The chromosome number of curlleaf mountain mahogany is 2n = 16 (Pyrah 1964). 



Distribution and Habitat: Curlleaf mountain mahogany occurs at elevations between 

 1,830 and 2,740 m (6,000 and 9,000 feet) in Utah on dry, rocky ridges usually on south- 

 ern or western slopes. Occasionally, it can be found in coarse soil on steep northern 

 slopes and among cliffs (fig. 14). Its range extends from Montana to Washington, 

 south to Colorado, northern Arizona, and California. 



Use: Curlleaf mountain mahogany is excellent winter game browse. In contrast to 

 true mountain mahogany, it is not fire tolerant, which may explain its absence on many 

 areas where it has occurred and would otherwise grow. This is likely the reason it is 

 often confined to rocky and severe sites that are not susceptible to burning because of 

 lack of fuel. Fire tolerance could be bred into it from C. montanus. Unfortunately, 

 because of the arborescent habit of this species, the bulk of the foliage in mature 

 stands is out of the reach of grazing animals (fig. 11); stands are often highlined as 

 high as the animals can reach. Thompson (1970) found that available browse in C. 

 ledifolius in the Manti-LaSal National Forest in central Utah could be increased con- 

 siderably if tops were pruned from April 20 to May 10 and from September 10 to 30. 

 Topping during other periods resulted in complete mortality. He reported that top- 

 pruned trees often produced to 200 percent more growth than unpruned trees. He 

 therefore suggested that this method could be used as a means of increasing available 

 browse on selected sites of big game winter ranges. Wood of curlleaf mountain mahogany 

 has a high density and burns slowly. It is prized as a barbecue fuel. 



Figure 14. — Curlleaf 

 mountain mahogany 

 growing on and 

 below granite 

 ridges. Mineral 

 Mountains, Beaver 

 County, Utah. 



11 



