Rosendahl: observations on betula 



449 



pyramidal tree, lending itself admirably to isolated planting for 

 ornamental purposes, whereas B. Sandbergi is a shrub with 4 to 8 

 ascending stems which occasionally attain the aspect of straggling 

 trees. It would be difficult to imagine how a pyramidal tree could 

 arise from parents like B. papyrifera and B. piimila. The former 

 has a habit of sending up mostly from a common root 2 to 4 stems 

 which grow in a spreading manner, each forming an irregular 



i'ig. I. a-d Betula papyrifera; e-f B. pumila var. glandulifera; g-h B. papyrifera x 

 pumila var. glandulifera; k-1 forma maxima; m-r B. lutea x pumila var. glandu- 

 lifera; s-t B. lutea. 



crown which is widest near the top. When only one stem is pres- 

 ent it is never strictly erect or regular. Betula pumila is a typical 

 shrub with ascending stems and branches. 



All these facts contradict Schneider's assertion as to the origin 

 and identity of Betula excelsa, and it seems more likely that 

 Winkler is correct in assuming it to be a garden form of B. 

 pubcscens. 



In the case of the hybrid between B. lutea and B. pumila var. 

 glandulifera, a somewhat similar intermediate position is shown in 



