Figure 16. — True mountain 

 mahogany showing a typical 

 twisted plumose aohene 

 ( near center) . 



The slowing effect of elevation on flower and fruit development is well demonstrated 

 by this species. On June 18, 1967, at an elevation of 2,380 m (7,800 feet), true moun- 

 tain mahogany was in late flower. Only 2 days later, at an elevation of 1,830 m (6,000 

 feet), it was in late fruit. True mountain mahogany averages 59,030 cleaned seeds per 

 pound (130/g) (Plummer and others 1968). 



There is a wide variation in ecotypes both geographically and by elevation. Leaf 

 size and shape are variable (fig. 12). A number of small-leafed true mountain mahogany 

 shrubs occur west of Richfield, Utah, on the lower foothills of the Pahvant Range. 

 These appear to be a distinctly different ecotype than those growing elsewhere. 



The chromosome number of true mountain mahogany is 2n - 16 (Pyrah 1964) . 



Hybridization: Our observations indicate that the stigmas of true mountain 

 mahogany mature before the stamens. Consequently, we believe artificial hybridization 

 by mass pollination would be possible when the flowers first open. 



Natural hybridization between the deciduous C. montanus and the evergreen species 

 C. ledifolius and C. intricatus occurs at many places in Utah where their ranges overlap 

 (fig. 13). Plummer and others (1957) reported that the more vigorous semievergreen 

 hybrids of C. montanus X C. ledifolius are relatively common in Utah, particularly along 

 the west slopes of the Wasatch Plateau and the Wasatch Mountains. Pyrah (1964) observed 

 that hybrids of C. ledifolius X C. intricatus are common because their flowering periods 

 overlapped. He found that hybrids of C. montanus X C. ledifolius are less common 

 because of a 2-week flowering period difference between the parental species. Hybridiza- 

 tion between C. montanus and C. intricatus was reported to be rare (Pyrah 1964) . 

 Development of strains useful for a variety of purposes, particularly range restoration, 

 should be possible by selection and artificial hybridization. Mountain mahogany species 

 and hybrids can often be distinguished by leaf characteristics (fig. 12) . 



13 



