145 DISPERSAL OF SEEDS. 
The Maple and Sycamore (AcER CAMPESTRE and A. PsEuUDo- 
PLATANUS) furnish good examples of seeds with large wings. In 
both species two or three are attached on one stalk; each seed has 
a long membranaceous wing, and is easily blown a long distance. 
The Hornbeam (Carpinus BetuLus) is winged in much the 
same manner, but in this case, the wing is a serrate bract to the 
base of which the seed is attached. 
The Elm seed has a very thin membrane all round it, and is 
wafted to long distances by the summer breezes; it grows in large 
clusters and immense numbers are produced by each tree. Of the 
two species of Elm (Unmus montana and U. CAMPESTKIS) only 
MONTANA ripens its fruit in this country. 
The Ash (FRAXINUS EXCELSIOR) also produces a samara. The 
wing is a kind of bract about 13 inches long, having the seed en- 
closed in the base. 
This blade has a slight twist in it, and when carried by the 
‘wind, sets up a spinning motion, which causes it to be carried much 
further than it would travel if quite flat. 
The Lime Tree (Tirta Europa) has its fruits in a bunch of 
four to six, attached toa stalk; on this is a membranaceous bract. 
It will carry the bunch of fruits some distance in a strong wind, but 
many fall under the tree. 
The Birch (BrTuLA ALBA) has a winged seed, which is developed 
between the scales of a catkin. 
The Scotch Fir (Prnus syLyxstRis) and the various introduced 
ConIFER#, have winged seeds produced between the scales of their 
cones. The wing is very large in proportion to the seed, and many 
are blown long distances, as they shake out of the cones, swinging on 
the tall trees. 
A great many other plants are adapted for wind dispersal of the 
