XXU INTRODUCTION TO BOTANY. 



The epidermis, or surface, is said to be, 



utrigose, when short, stiff hairs lie close-pressed to the sm-face, and 



all in one direction ; striyillose, when such hairs are very short 



or small. 

 tomoitose or cottony, when the hairs are soft, short, dense, somewhat 



interwoven, and usually white or whitish. 

 xvoolly, when the hairs are loosely intricate and long, like wool. 

 mealy or farinose, when the hairs are very minute, intricate, and 



white, and come ofif readily, ha\dng the appearance of meal or 



dust. 

 canescent, canous, or hoary, when the hairs are minute, close-pressed, 



and white, and not readily to be distinguished separately by 



the eye, but giving a general whitish hue to the epidennis. 

 glaucous or glaucescent, when of more or less a pale bluish-green, often 



covered with a bloom like that on a plimi or cabbage-leaf. 



148. Hairs are often branched. If forked from the base, the forks 

 spreading in opposite directions, the hairs are said to be attached by the 

 centre. If several branches radiate horizontally, the hairs are stellate, or 

 star-like. Stellate haii-s become stellate scales when the rays are confluent 

 at base ; and the surface is said to be scaly or lepklote. 



149. The term gland is given to several different productions, and 

 principally to the four following : — 



1. Small, wart-like or shield-shaped bodies, either sessile or some- 



times stalked, of cellular or somewhat fleshy consistence, occa- 

 sionally secreting a small quantity of oily or resinous matter, but 

 more frequently dry. They are generally few in number, often 

 definite in their- position and form, and occur chiefly on the 

 petiole or principal veins of leaves, on the branches of in- 

 florescences, or on the stalks or principal veins of bracts, sepals, 

 and petals. 



2. Minute raised dots, usually black, red, or dark-coloured, of a 



resinous or oily natiu-e, always superficial and apparently 

 exudations from the epidermis. They are often very numerous 

 on leaves, bracts, sepals, and green branches, and occur even on 

 petals and stamens, more rarely on pistils. "WTien raised on 

 slender stalks they are called pedicellate glands, or glandular 

 hairs, according to the thickness of the stalk. 



3. Small, globular, oblong, or linear vesicles filled with oil, im- 



bedded in the substance of leaves, bracts, floral organs, or 

 fruits. They are often very numerous, like transparent dots ; 

 sometimes few and determinate in form and position. In the 

 pericarp of Umhellifera they are remarkably regular and con- 

 spicuous, and take the name of vittce. 



4. Lobes of the disk, or other small, fleshy excrescences within the 



flower, whether from the receptacle, calyx, corolla, stamens, or 

 pistils. 



II. Anatomy and Physiology. 



{^Abridged from the writings of Professor Lindley and Professor Asa Gray.) 



1.50. Vegetable Anatomy, or the study of the microscopical structure of 

 the compound organs of plants, and Vegetable Physiology, or the study of 

 the functions which each organ })erforms duiing life, are distinct and 

 extensive branches of botanv, with which the merelv svstcmatic botanist, 



