MORPHOLOGY OF THE SEEDLING roe 
of the cotyledon to make one think it really a leaf, and it 
is only by studying many cases that the botanist is enabled 
to class all cotyledons as leaves in their nature, even if they 
are quite unable to do the ordinary work of leaves. The 
study of the various forms which the parts or organs of a 
plant may assume is called morphology ; it traces the rela- 
tionship of parts which are really akin to each other, 
though dissimilar in appearance and often in function. 
In seeds which have endosperm, or food stored outside of 
the embryo, the cotyledons usually become green and 
leaf-like, as they do, for example, in the four-o’clock, the 
morning-glory, and the buckwheat; but in the seeds of 
the grains (which contain endosperm) a large portion of 
the single cotyledon remains throughout as a thickish 
mass buried in the seed. In a few cases, as in the pea, 
there are scales instead of true leaves formed on the first 
nodes above the cotyledons, and it is only at about the 
third node above that leaves of the ordinary co 
kind appear. In the bean and some other yet 
plants which in general bear one leaf at a 
node along the stem, there is a pair produced 
at the first node above the cotyledons, and 
the leaves of this pair differ in shape from 
those which arise from the succeeding por- 
tions of the stem. 
‘45. Classification of Plants by the Number 
of their Cotyledons. In the pine family the pag yo Ger. 
germinating seed often displays more than  minating Pine. 
two cotyledons, as shown in Fig. 12; inthe Agel ores 
majority of common flowering plants the seed con- 
tains two cotyledons, while in the lilies, the rushes, the 
