I1.] PLANT STRUCTURE AND GROWTH. 29 
lower end of the stem bear neither, and are called 
roots. These latter serve a double purpose,—they 
fix the plant in the earth, and 
also imbibe moisture from it. 
They are never green, and they 
avoid the light. The stem, on 
the contrary, is ever seeking 
the light, and usually green. 
The leaf is a thin, flat plate 
attached by a stalk to the 
stem or branch. Fig. 36 re- 
presents a thin slice cut through 
the thickness of a leaf. Ep 
shows the colourless epidermic 
cells bounding the upper and 
lower surfaces of the leaf. Be- 
neath them is the green-celled 
parenchyma, and between these 
layers of parenchyma, which are 
closely packed, there are others 
loosely arranged (LP) to form 
the intercellular spaces (IS). 
Within this are seen the fibro-vascular bundles (Fv). 
St marks the presence of the stomates. 
The food of a plant is of two kinds—liquid and 
gaseous. The liquid 
food is obtained from 
the soil through the 
roots, and consists of 
water in which various 
mineral salts are dis- 
solved. These salts con- 
