HIE LEAF. 
71 
( h ) MODIFIED LEAVES. 
Leaves are variously modified and serve for other 
purposes than those already described. They may be 
fleshy in character and serve as storehouses for nutri- 
tive material, as seed-leaves, or they may serve for the 
storage of water, as in Agave and Aloe. In some 
instances, particularly when situated near the flowers, 
they lose their green color, as in the dogwood, skunk 
cabbage and others. In other cases they are modified 
so that they serve as a trap for insects, as in species of 
Sarracenia and Drosera. The petiole may become en- 
larged and perform the functions of the leaf, as in the 
acacias, of Australia; or they may serve as a means for 
floating the plant, as in the water hyacinth. The stip- 
ules may likewise be modified, becoming leaf-like, as in 
the pansy, or metamorphosed into thorns, as in the 
locust. In some cases the leaves are very much 
reduced, their functions being performed by the stem, 
as in Cactacese, or even by the roots, as in some orchids. 
(*) PRE FOLIATION OK VERNATION. 
Prefoliation or vernation is the disposition of leaves 
in the bud. The terms used to describe the folding 
of the leaves in the bud are derived from an examina- 
tion of transverse sections of the bud. The following 
are some of the terms which are employed : condupli- 
cate, when the lamina of the leaf is folded lengthwise 
along the midrib so that the two halves of the upper 
surface lie together, as in the Magnoliacese ; plicate 
or plaited, when the lamina is folded along the 
veins, like a closed fan, as in the maples ; convolute, 
when rolled lengthwise and forming a coil in cross 
section, as in the Rosacese ; involute, when both mar- 
gins are inrolled lengthwise on the upper surface, as 
