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YOSEMITE NATURE NOTES 



WHITE ALDER 

 AInus rhombifolia Nutt — Birch Family (Betulaceae) 



This is one of the most common 

 trees of the Transition Zone where it 

 is found in considerable abundance 

 in moist sandy soils bordering 

 streams, up to 4,500 feet in elevation. 

 It is particularly common at Happy 

 Isles, about Mirror Lake, in many 

 places along the banks of the Merced 

 River in Yosemite Valley, while Alder 

 Creek near Wowona owes its name 

 to the abundance of these trees at 

 certain locations along its course. 



The white alder can be readily 

 identified by its smooth, steel-gray 

 bark (on young trees) which become 

 scaly and ridged with age, and the 

 conspicuous, cone-like features — one- 

 quarter to one-half inch long — which 



bear the seeds, and which are known 

 as strobiles. 



The leaves are alternate on the 

 branches, are large (one and one- 

 half to two inches wide and from two 

 to three inches long), a dark lustrous 

 green on the upper surface, ovate in 

 outline with coarsely toothed margins 

 and prominent veins extending to the 

 margins. 



Both staminate and pistillate flow- 

 ers, while borne in separate clusters, 

 are found on the same tree. Both are 

 partially formed in the summer pre- 

 vious to maturity. The former are con- 

 tained in long, pendent, tassel-like 

 clusters which are very conspicuous 

 in the late winter and early spring 



Photo by Brockman 



Foliage and strobiles of white alder {Inch squares on background) 



