UTJDS. 
89 
iiiicl other forest trees in our climate, and also in most of our 
common >>erbaceous plants : they are called Exogenous stems, 
signifying to grow outwardly ; plants with such stems spring 
from seeds with two cotyledons^ and are therefore called dicoty- 
ledonous plants. Stems which grow internally^ as palms and 
grasses, are called Endogenous^ signifying to grow inwardly ; 
the wood, instead of circling around the first formed substance, 
is pushed outward by the development of new fibers in the cen- 
ter ; this kind of stem is peculiar to plants whose seeds have 
hut one cotyledon^ and are therefore called monocotyledonous. 
LECTUKE YIII. 
BUDS. 
46. A PJD is a protuberance formed by a new shoot. The 
normal situation of the bud is at the nodes, and it usually 
appears at the axil of the leaf. In the embryo is a short axis 
or stem crowned by two or more undeveloped leaves, or a hud. 
The apex of a growing stem is always crowned with the rudi- 
ments of a new plant, or with a hud. The scales of buds usu- 
ally envelop each other closely ; the exterior ones being dry 
and hard, the interior moist, and covered with down ; they are 
also furnished with a kind of resin, or balsam, Avhich prevents 
the embryo from being injured by too much moisture. Buds 
have been known to lie for years in water, without injury to 
the germ within. The sap is the great fountain of vegetable 
life ; by its agency new buds are yearly formed to replace the 
leaves and flowers destroyed by the severity of winter. 
If we plant a slip of Geranium, it either sprouts from the axil of a leaf, or from 
knots in the stem, which answer the same purpose as the leaf, by slightly inter- 
rupting the circulation of the juices, and thus affording an accumulation of sa,p 
necessary for the production of a new shoot. The different periods of the bud 
have been distinguished as follows : the point or nucleus which first appears, is 
called the eye ; when this begins to swell so as to be apparent, it is termed the 
button ; and in a more mature state the hud. Herbs and shrubs have buds, but 
ihese usually grow and unfold themselves in the same season, and are destitute 
of scales ; while the buds of trees are not perfected in less than two seasons, and, 
in some cases, they require years for their full development. 
a. Nature is bounteous in her provisions, and lays in a large stock of these rudi- 
ments of future plants, so that when some fail of maturing, others are always 
ready to take their places. In the spring, the growth of the leaves and branches 
of trees is rapid ; but as summer advances, the progress of vegetation seems almost 
suspended. Yet nature, instead of resting in her operations, is now busy in pro* 
Monocotyledonous stems. — 46. Bud — Its normal situation — Bud iu the embryo — In a growing stem— . 
Scales of buds — Agency of sap— The eye, button, and bud- -Herbs and slirubs destitute of scaly bad* 
a. Period iu which the formation of buds commences. 
