THE EOOT. 
having performed this office, then dies, and no process can re- 
store it to life. The onion, beet, and carrot, are biennial plants. 
Their thickened fleshy roots contain within their cells, starch, 
sugar, &c., and afford a reservoir of nourishment for a new 
stem and branches for the second year. Perennial Boots — are 
those whose existence is prolonged a number of years to an in- 
definite period ; as the asparagus, geranium, and rose ; also 
trees and shrubs. Climate and cultivation affect the duration 
of the roots of vegetables. Many perennial plants become an- 
nual by transplanting them into cold climates : the garden 
nasturtion, originally a perennial shrub in South America, has 
become in our latitude an annual plant. 
a. Wheat is annual, if sown early in Spring, but biennial if sown in Autumn ; the 
annual Mignonette, by removing its flower-buds the first year, and keeping it in a 
proper temperature, may be rendered perennial and shrubby. Many flowering 
plants may be brought to flower later, by pinching off the early blossoms. 
h. Perennial roots do not, like the biennial, depend upon the stock of the preced- 
ing year, but annually produce new roots and form new accumulations ; sometimes, 
as in the Dahlia and Orchis, in separate portions of the root, one portion annually 
perishing, and a new portion formed ; so that the plant is perpetuated, in its off 
spring, year by year. In the potato the tuberous stem performs this office. In 
trees and shrubs the juicy trunk or stem contains nourishing matter. It is found 
that the radicle continues to extend itself in length ; and, strictly speaking, the real 
root is composed only of those delicate fibers continually forming by the develop- 
ment of new cells, and that these consist of newly formed tissue full of vitality. 
32. FoKMS OF Roots. — ^The forms of roots depend upon the 
mode in which the axis descends and branches. Among the 
varieties in the forms of roots are the following : 
BrcmcJiing or ramose root (Fig. 12). Fig. 12. 
This consists of numerous ramifications, 
resembling in appearance the branches 
of a tree ; this is the root of most trees 
and shrubs. Some of these branches 
penetrate to a great depth in the earth, 
and others creep almost horizontally near 
its surface. Experiments have been 
made, which show, that branches by being buried in the soil 
may become roots ; and roots, by being elevated in the atmos- 
phere, become branches covered with foliage. We often see 
the upturned roots of trees throwing out leaves. Branching 
roots terminate in fibers and spongioles ; these are in reality 
the proper roots, as they imbibe through pores the nourish- 
ment which the plant derives from the earth. Nature furnishes 
this nourishment in the moisture and various salts which are 
contained in the soil. Eoots do not form branches in any reg- 
ular order ; the branches of stems, are more or less symmetri- 
cal, being produced by the development of buds which have a 
Perennial roots. — 32. Forms of roots — ^Branching root. 
