THE ROOTS OF PLANTS. 



15 



with the first materials of its development and 

 nutrition. Tliey miftlit equally be considered 

 as short and fleshy subterraneous stems, and the 

 eyes whicli spring from them miglit be viewed 

 as buds. Or might we not rather regai-d them 

 as subten-aneous cotyledons, containing the germ 

 of the future plant, and the nourishment neces- 

 sary for its development. 



4. Bulbous roots are 

 either scaly f, or coat- 

 ed g. The onion is 

 of this kind of root, 

 and is formed of a 

 thin flat tubercle call- 

 ed a disk, which, 

 at its lower part, pro- 

 duces a fibrous root, ^ ^ 

 and on its upper supports a bulb, which is a 

 bud of a particular kind, formed of a number of 

 coats or concentric layers, one above the other. 

 From the centre of the bulb, a short or her- 

 baceous stem is produced, wliich dies down. 

 Of this kind are also the lily, hyacinth, garlic, 

 and other bulbous plants. 



Such are the principal forms which we find 

 the roots of plants assume ; yet, of these forms 

 there are many modifications and varieties. 

 Here, as throughout her other works. Nature 

 does not adhere servilely to artificial or system- 

 atic divisions. She sometimes obliterates, by in- 

 sensible gradations, those dififerences which we 

 at first thought so complete and decided ; and 

 many of these modifications are accomplished to 

 accommodate the plant to the nature of the 

 circumstances amid which it is placed. Thus, 

 the radicles or fibrils of the roots are compara- 

 tively larger, and more abundant, the looser the 

 soil in which the vegetable lives. When the 

 extremity of a root happens to meet a stream 

 of water, it elongates, divides into capillary and 

 branched fibrils, and constitutes what is called 

 by gardeners a fox's tail. This circumstance, 

 which may be produced at any time, shows why 

 aquatic plants generally have much larger roots 

 than others. AU the roots which cannot be re- 

 ferred to any of the four divisions above enum- 

 erated, retain the general name of roots ; but a 

 few particulars may be added regarding the var- 

 iety of structure, as useful to practical botanists. 

 The root is said to be fleshy, when besides being 

 manifestly thicker than the base of the stem it 

 is at the same time more succulent, as in the 

 carrot, turnip, &c. On the contrary, it is said 

 to be woody when its structure is more solid, 

 approaching, in some degree, to the hardness of 

 wood. This is the case in most woody vegeta- 

 bles. Simple roots have a single tapering body 

 entirely without divisions ; a branched root is 

 one divided into more or less numerous rami- 

 fications, always of the same nature as itself. 



which is the case in most of our common trees, 

 as the oak, elm, ash. The root is vertical when 

 its direction is perpendicular to the earth's 

 centre, as the carrot, radish ; oblique, as in the 

 iris; or horizontal, as in the elm; not unft-equently 

 these positions are assumed by the different 

 radicles of one root. As to shape, roots are 

 called fusiform when they are thick in the 

 middle, and taper to both ends, as in the radish ; 

 nafiform, as in the common turnip, Spanish 

 radish ; conical, with the form of a reversed 

 cone, as in the beet, parsnip, carrot ; rounded, as 

 in the earth nut ; testiculate, when it has one or two 

 rounded egg-shaped tubercles, as in Jerusalem 

 artichoke; in this root, one of the tubercles is 

 finn, soUd, and somewhat larger than the other ; 

 it is that which contains the rudiments of the 

 stem which is to grow in the ensuing year ; the 

 other, on the contrary, being soft, wrinkled, and 

 smaller, contained the germ of the stem which 

 has been last developed, and on whose growth 

 it expended the greater part of its amylaceous 

 or starchy substance ; palmate, when the tu- 

 bercles of the root are divided about the middle 

 into lobes like fingers, as in the spotted orchis, i. 



18. 



Digitate, when this division extends nearly to the 

 base of the root, as in some of the others of the 

 genus orchis ; k, creeping,a,s in mint and other fa- 

 miliar plants; AreoWy, when the ramification of the 

 root presents at intervals a kind of enlargement or 

 knots, which impart somewhat the resemblance 

 of a necklace, as in the 

 drop wort, fig. I. These 

 knots, however, are not to 

 be confounded with the 

 true tubercles, which al- 

 ways contain the rudi- 

 mentsofanewstem. Gran- 

 ulated,\yh\c}i present a mass 

 of small tubercles contain- 

 ing eyes, by which a 

 new plant is produced, as in the saxifrage, saxi- 

 fraga granulata; fasciculate, when foi-med of 

 numerous thick, simple, or branched radicles, as 

 in asphodel and ranunculus ; articulated, or 

 forming joints at regular dietances, as in gratiola; 

 contorted, when curved in different directions, as 

 in bistort ; capillary, formed of a number of 

 slender capillary tubes, as in wheat, barley, 

 grasses ; comose, when the filaments are branched 



