SPECIAL FORMS OF LEAVES 271 
Fic. 243. — A portion of a Sweet Pea, showing one leaf (1), a portion 
of which is transformed into a tendril (é). 
they have lost much or all of their power to make food, and have 
become apparently useless or have taken on other functions. 
A very common modified form of the 
leaf is the scale. The most familiar 
example of scales is furnished by the 
buds of shrubs and trees, where they 
form a protection for the inner vital 
portions of the bud. These scales are 
considered leaves which have been pre- 
vented from developing by being so 
closely crowded in the overlapping ar- 
rangement. The leaves of underground 
stems, which do not get to the light, 
appear as small scale-like bodies with- 
out green tissue, and apparently have 
no function. Sometimes scales are 
fleshy and are used for food storage, as 
Fic. 244. — A branch of a 
Barberry, showing the leaves 
transformed into thorns. 
in Lily bulbs, Onions, ete. In the Asparagus the leaves are 
scale-like and the food-making is mostly done by the stem. 
