20 ARBORETUM ET FRUYICETUM BRITANNICUM. 
104. Tflia arnericana pubéscens, 
On a general view of the trees, the most obvious external differential cha- 
racteristics of the European and American limes appear to us to be, that 
the former have regularly cordate, and the latter obliquely cordate, leaves. 
The other American limes we consider to be nothing more than varieties of 
this species. Layers. These trees only thrive in warm sheltered situations. 
The American lime is readily distinguished from the European limes by the 
largeness of its leaves, which are 3in. to 4 in. wide, heart-shaped, acutely 
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105. Tilia amertchna. 
pointed, coarsely and mucronately serrated, deep green and glabrous on their 
upper sides, and pale green beneath. Some of them have a tendency to be 
slightly pubescent ; but they are generally smooth and shining. In winter, 
this species is readily recognised by the robust appearance of the trunk and 
branches, and by the dark-brown colour of the bark on the young shoots. 
This circumstance alone is a very marked distinction ; and has, no doubt, pro- 
cured for the species the name of the black lime tree. 
