THE ROOT. 29 



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 nnmber 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 

 sprmg, 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. Forms of Koots. — ^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 : 



Branching 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 roorts ; 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. J^ature furnishes 

 this nourishment in the moisture and various salts which are 

 contained in the soil. Koots 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. 



