THE PARTS OF A SEED-PLANT 317 



upon careful examination to lje already a miniature plant, 

 for it has a stem (s) bearing at its lower end the beginning of 

 a root (r) which becomes apparent when the seed sprouts; 

 while at the upper end of the stem are borne a pair of flesh}' 

 leaves (1) which after sprouting turn green, and between 

 them a tin_y bud (b) which is destined to grow into the stem, 

 leaves, flowers, and fruit of the mature plant. Each of these 

 parts of the embrj'o has been given a special name. The 

 little stem which bears all the oth(>r parts is the caulicle.^ 

 Each of the first leaves is a cotyledon:- The bud at the top 

 of the caulicle is known as the plumule,^ while the rudimen- 

 tary root at the lower end is called tiie radicle.^ 



93. The seedling and its development. When the seed 

 germinates, the radicle is the first part to appear (Fig. 279B). 

 Soon it grows into a root (Fig. 279C) covered with hairs 

 through which absorption of soil-water takes place. Mean- 

 while the cotyledons have been feeding upon the albumen 

 to get material for their growth and for the elongation of the 

 caulicle and root; and when finally this reserve food is ex- 

 hausted, the empty seed-coat is cast off, the cotyledons become 

 green and expand in the sunlight (Fig. 279D), and the plumule 

 develops into a leafy shoot (Fig. 279E). As the root pene- 

 trates downwards into the soil it sends forth branches in 

 various directions (Fig. 2171). At the same time the leafy 

 shoot grows upward developing stem and leaves l^y the con- 

 tinual unfolding of a bud at its tip which began as the 

 plumule (Fig. 279F). 



The place at which a leaf joins the stem is called a node,'" 

 and the length of stem between two nodes, an internode." 



' Caul'i-clc < L. cauliculus, diminutive of canliK, stalk < Cir. ImuIik, 

 stalk. 



^ Cot-y-le'don < Gr. kolijle, a .shallow cup, -which some cotyledons are 

 supposed to resemble. 



^ Plum'ule < L. plumula, a little plume, which the plumule of certain 

 plants, such as the peanut or almond, somewhat resemble. 



* Rad'i-cle < L. radiculiis, diminutive of 7-adix, a root. The term 

 radicle is sometimes used so as to include the caulicle, and caulicle is 

 sometimes made to include the radicle as above defined; but the terms 

 are coming to be understood in the sense here adopted. 



■'' Node < L. nodus, a knot, the joint being Kkened to a knot in a cord. 



« In-'ter-node < L. inter, between. 



