MONOCOTYLEDONS. PARTS OP A TREE. 49 



of the usual shape. These enlarge and expand, and 

 from their axil or inner angle, appear one or two other, 

 ordinary leaves, which, with the new joint of the stem, 

 rise and expand in like manner. 



156. But all plants do not have two seed leaves. A 

 kernel of maize or of wheat has only one cotyledon. 

 This is also true of all the grains and grasses and of some 

 other plants. Such plants are named Monocotyledonous 

 Plants, (plants with one seed leaf.) A plant of this kind 

 comes up with one single leaf rolled together, as may be 

 seen in the case of Indian corn or common wheat. When 

 this leaf is somewhat expanded, another leaf appears 

 within it, growing from a second joint in the stem. From 

 each successive joint grows one leaf, till the corn-stalk or 

 grass-stem is complete. 



157. The stem of a tree has external and internal 

 organs. The external are the trunk, the boughs, limbs 

 or arms, the branches, the branchlets, the spray, and the 

 shoots or twigs. 



The trunk is the main body of a tree. It begins at the 

 collar, and, after rising to a greater or lesser height, 

 divides into branches or ramifications. All the divisions, 

 large and small, are called branches or boughs. The 

 largest are called also limbs or arms. A division of a 

 branch is called a branchlet ; and all the smallest divis 

 ions together are called the spray. Shoots or twigs are, 

 properly, those of not over one year s growth. 



158. A shoot begins in the spring to grow from a bud 

 at the end of a branch called a terminal bud, or from an 

 axillary bud, or one in the axil of last year s leaf, that is, 

 the angle above the leaf, between it and the stem. 



159. The internal organs are the inner bark, in several 

 layers, the alburnum or sap-wood, the heart-wood, the 

 pith, &c. 



