672 THE ASPEN. 



to the twig as do the buds of the Willow, neither are they downy 

 nor covered with gum, like those of the Black. Poplar ; the terminal 

 bud appears to be usually abortive. The colour of the twigs varies 

 from an olive to grey-brown, and the young shoots are covered with 

 a greyish-white wool. The leaves are also downy when young, and 

 in one variety the mature leaf has a silken coating on its under- 

 surface : it is more usual to find both surfaces of the leaf-blade hairless, 

 and the under surface the lighter in colour. The upper side, which 

 has usually a dull surface not conspicuously dark amongst other trees, 

 is occasionally of a dark glossy green. The ribs project more on the 

 upper side than on the lower, and make a pattern of pale yellow. 

 The leaves are arranged singly from several points on the twig. 

 They are about two inches across, and their outline is nearly round, 

 except for a point opposite the stalk, while the margin is cut into 

 large blunt teeth, unevenly distributed. The leaf-stalk is longer than 

 the leaf, and the portion close up to the leaf-blade is flattened, and 

 blade and stalk set at right angles, which results in a rotary move- 

 ment when the breeze sways the leaf. The stalk curves over, and 

 most of the leaves are pendent. 



