144 BOTANY 
Grass leaves, it will be noted have long sheathing 
bases, and just where the sheath begins to clasp the 
stem is a membranous scale called a ligule. 
Stipules are outgrowths from the leaf base or 
sheath, well seen in the bean, rose, and kawakawa. 
Modifications of leaves to suit special conditions 
have already received attention. Leaves are modified 
for climbing in the clematis and the pea, to form 
spines in the barberry, and to form traps for insects in 
the pitcher plant and sundew. The more important 
modifications to form bracts, spathes and floral leaves 
of different kinds will be dealt with in connection 
with the flower and inflorescence. 
Plants that are completely parasitic, like the 
broom-rape and dodder, have no leaves and no 
chlorophyll since photosynthesis is unnecessary. 
Foutace LEAVES AND SEED LEAVES. 
Foliage leaves are distinetly organs of the plant 
doing work necessary to its existence; @.e. carrying 
out the process of photosynthesis and forming an 
avenue for the ingress and egress of gases as well as 
a means of exit for the water of transpiration. Seed 
leaves, on the other hand, are merely storehouses of 
reserve material, which will supply the young seedling 
with nourishment until it has obtained a root-hold and 
become green, and thus reached a stage at which it 
ean fend for itself. 
The starch stored in the foliage leaves is stored 
only for a short period and is for immediate use, while 
that accumulated in the seed leaves is stored for a 
long period, and is not called into requisition till the 
seed germinates. 
The foliage leaves contain chlorophyll for carbon 
assimilation, while the seed-leaves, having no such 
function to perform, have no chlorophyll. 
