822 



for the omission of this variety (allowed by the same author, two years 

 before, in the ' Edinburgh Catalogue') we now find in the ' Manual ' 

 another variety, not of B. alba, but of B. glutinosa, introduced under 

 the name of " pubescens." 



Thus, taking the Floras together, we have three species of birch- 

 tree — B. alba, B. pendula and B. glutinosa ; the last of these three 

 being subdivided into the typical (usually glabrous) form and the va- 

 riety pubescens. In this medley of contradictory views, I hold that 

 Smith and Hooker are correct, in describing only one species ; and 

 that Lindley's B. pendula, and Babington's B. glutinosa, are merely 

 forms of that one species, the Betula alba of Linnaeus. 



Dr. Lindley's name stands very high among botanists, and deserv- 

 edly so, but his botanical reputation has never been considered to rest 

 on any skill in the discrimination and determination of species ; and 

 since both Hooker and Babington have thought fit to reject B. pen- 

 dula, we may safely pass it over at present, as a mere book-species. 



Betula glutinosa and its variety pubescens, still remain open for in- 

 vestigation. In the Manual, we are told that B. alba is readily dis- 

 tinguished from B. glutinosa " by its leaves, but more certainly by its 

 fruit." The difference between the leaves of the two is thus stated: — 

 B. alha. — " Leaves rhomboid-triangular douWy serrate acuminate." 

 B. glutinosa. — " Leaves cordate-ovate unequally serrate acute." 

 This reads very satisfactory on paper, and may appear equally sa 

 in small specimens for the herbarium. Unfortunately, however, for 

 this ready distinction of the species, while old trees, with pendulous 

 branches, are clothed with leaves exactly corresponding with this de- 

 scription of the leaves of Betula alba, the seedling plants which spring 

 up underneath them, produce cordate and pubescent leaves. The old 

 trees are thus B. alba, while their young progeny are B. glutinosa 

 variety pubescens. Moreover, I have repeatedly seen, on the same 

 single tree, that the upper and drooping branches bore the rhomboid 

 leaves of B. alba, while the lower ascending or nearly horizontal 

 branches were clothed with the cordate-ovate leaves said to be cha- 

 racteristic of B. glutinosa. And still, on the same trees, I have occa- 

 sionally observed completely cordate and pubescent leaves, like those 

 of the seedling plants, produced on suckers from the root, on soft 

 shoots near the base of the old trunk, on late autumnal branchlets, 

 and on those fast-growing shoots which push out where branches 

 have been lopped. 



The serratures of the leaves are equally variable as their forms, and 

 doubly serrate leaves may be seen growing on the same tree with un- 



