24 



ANALYTICAL CLASS-BOOK OF BOTANY. 



counterpoise. If you examine the roots of any atrong, 

 hardy, herbaceous plant, you will find woody tissue, or 

 fibre, in the same proportion which it bears to the stem. 

 The fibrils, or growing points, are in all cases composed 

 of parenchyma. Sometimes, but very rarely, ducts are 

 found in the root. 



128. Organogkaphy, or Structural Botany, is that 

 branch of the science which comprehends a study of the 

 organs as pieces of machinery, having certain relations, 

 and adapted to certain ends. It relates chiefly to 

 Strdctdee and Form. 



ORGANOGRAPHY OF THE ROOT. 



129. Parts Defined. — The main body, or fleshy 

 part of the root, is called the Caddex, and the fibrous 

 portions are termed Fibrils. See Root Forms, Plate 

 VI. That part of the root which unites it to the 

 radicle, or base of the stem, is called the Base, and 

 sometimes also the Crown or Collar. In the hair-like 

 processes with which most roots are abundantly clothed, 

 all the vital forces of the organ reside. 



130. The Primitive Eoot is the main body of the 

 organ, or that which proceeds directly from the radicle. 

 It is generally branched, as may be seen by a reference 

 to the Root forms just referred to. 



131. Secondary Roots.' — When any part of the 

 stem is buried in the ground by accident, design, or the 

 habit of the plant, it will seek to maintain its life by 

 putting forth roots. Creeping and running stems thus 

 buried, or in close contact with the ground, send down 

 roots at every joint; and this is the secret of success 

 with cuttings and laycrings, that the branches thus put 

 in the ground will strike root. Such roots, and all others 

 which do not belong to the Primitive root or its branches, 

 are called Secondary or Adventitious Roots, as in 

 the Strawberry, fig. 11. 



132. The GtRowing Points. — The vital activities 

 reside wholly in the fihrils. The growing tissue, how- 

 ever, is not at their extreme points, but immediately 

 behind them. The extremities themselves consist of 

 older tissue, which has been carried along from the base 

 of the radicle, and combines with its insinuating points 

 the older and firmer cells, that peculiarly adapt it for 

 shielding the tenderer portions, by which it ia continually 

 displaced, and pushed forward in growth. 



ROOT FORMS. 



133. In respect to external shape, roots may be 



In what proportion is wood formed? Define Orgamgrapliy. Parts ..f tlie 

 Eoot. Define Candox. Fihrils. Primitive Boots. Secondary. Which parts 

 vitally active ? Growing tissue, where deposited ? Boot Forms. Define the 



divided into the Branching, Fibrous, Granulated, Napi- 

 orm. Fusiform, Premorse, Tuberous, Fascicled and 

 Conical. 



134. Branching Roots belong to trees and shrubs, 

 and are of a woody structure, as in fig. 1 . 



135. Fibrous Roots are found in most of our Grasses 

 and annual plants. They are chiefly composed* of fibrils, 

 and are therefore very tenacious of life. See figs. 2, 10, 

 11 and 15. 



136. Granulated Roots consist of small knobs, or 

 tubers, strung together by fibrils, as in the Wood Sorrel, 

 fig. 3. 



137. The Fusiform Root {spindle-form) is fleshy 

 and tapering at both ends, as in the Radish, fig. 5. 



138. The Napiform Root is a variety of the fusi- 

 form, with the eaudex greatly thickened, as in the English 

 Turnip, fig. 4. 



139. The Conical Root is also a variety of the 

 fusiform, and is distinguished by its tapering regularly 

 from the base to the apex, as in the Carrot, fig. 9. 



140. The Tuberous Root consists of one or more 

 fleshy knobs, or tubers, united at their base by fibrils, as 

 in the Orchis, flg. 8. This form must not be confounded 

 with the Tuber, such as the Potato, which belongs to 

 stem forms. 



141. The Premorse Root is an abbreviated conical 

 root, appearing as if cut or bitten off at the lower extre- 

 mity, as in the Devil's Bit, a European plant (fig. 6), 

 which was named from this circumstance. The common 

 Birdfoot Violet of our wood-sides is also a good example. 



142. The Fascicled {bundled) Root seems to con- 

 sist of an inordinate growth or swelling of the principal 

 divisions of a fibrous root into a number of fleshy pro 

 cesses, as in the Early Crowfoot, the Peony and the 

 Dahlia, fig. 7. A variety of this form developes into 

 five hand-like divisions, and is hence called Palmate. 



PERIODS OP duration. 



143. In respect to their continuance, roots may b< 

 divided into Annual, Biennial and Perennial. 



144. Annual Roots. — These belong to such plants 

 as spring from the seed, arrive at maturity, flower, and 

 bear seed in their turn, all in the course of one season. 



145. Such roots are always flbrous, as may be seen 

 in the Convolvulus, fig. 10, in Barley, Oats, and many 

 common herbs and weeds of our gardens and kitchen 

 doors. They are only adapted to absorption ; and in the 

 rapidity of their vital movements, the nutriment is ex- 



Branching, Fibrous, Granulated, Fusiform, Napiform, Conical, Tuberous, 

 Premorse, Fascicled. Duration of Eoota 



