B O T A N Y. 



citing off; because, as soon as they have gained a 

 ertain depth, they proceed laterally as readilv as 

 hey descend. Indeed, a certain decree of influence 

 >f the air seems to be necessary to them : as the 

 oots of some trees take a very extensive horizontal 

 ange, keeping at a very regular depth from the 

 urface, however unequal this maybe, even from one 

 ide of a ditch to the other, without varying much in 

 listanee from the air. 



The roots of an air plant (Acrides] hung up in a 

 noist hot-house, a!! tend towards the back wall, or 

 o the nearest solid body. A growing plant bound 



the periphery of a wheel, kept constantly in mo- 

 ion, directs till its roots to the centre or nave of the 

 vheel. The attraction of the solids seems to be the 

 :ause of the inclination of the roots in both these 

 :ases. Roots are attracted by water, or by those 

 :lement,s on which they feed ; manure laid on the 

 surface will cause working fibres to rise ; and in dry 

 seasons they will descend deeper in search of mois- 

 ;ure. 



As soon as the first spur-like root issuing from a 

 ;eed enters the soil, it emits small fibres from its point 

 md along its sides ; some of these become branches, 

 A'hich, in their turn, also eject fibres along their 

 ivhole length ; these are again divided and sub- 

 livided, until the whole system of roots is formed, 

 ind thus they continue annually extending as they 

 ire prompted by the demands of the head. The 

 oots and head of the plant are correlative, and are 

 ilways naturally proportioned to each other. No 

 extension of the one can possibly take place without 



1 corresponding extension and enlargement of the 

 ather. 



The fibres (spongiolcs) are the real roots or mouths 

 if the plant, by which they imbibe or extract nourish- 

 ment from the earth ; for, though it be perfectly 

 reasonable to suppose that the spongy bark of the 

 lamer ramifications also imbibe alimentary matter, yet 

 to the working fibres is the system chiefly indebted 

 for the principal share of the nourishment required. 

 These delicate bodies are beautifully organised, and 

 well fitted to take up those gaseous and aqueous 

 elements necessary to the plant ; their syphon-like 

 form, beset with hair-like appendices, enter into every 

 cavity and interstice of the soil in search of food, 

 which these convey into the body of the root ; and it 

 is observable, that they are more or less numerous 

 according as the plant is more or less vigorous. In 

 water, or in finely comminuted soil, they are much 

 divided, and are ejected like tufts of hair from the 

 ends of the principal divisions of the root. 



Fibres can only be produced in the earth or water, 

 or in any other humid medium. Proper roots are 

 often produced in the air, as may be seen on the 

 cherry-tree, the grape-vine, and many other plants, 

 when placed in damp or shady situations. The Indian 

 fig, or banyan tree, is celebrated on account of its 

 tendency to produce and throw down roots from its 

 branches, which, fixing in the ground, become stems 

 to support a new birth of branches which rise from 

 that part of the branch whence the root has descended 

 Such roots, however, produce no fibres, because, a; 

 before observed, they are too delicate to be exserted 

 in dry air. 



There is no question but that these roots, thougf 

 destitute of spongioles, have the power of inhaling 

 through their vascular bark those qualities floating ir 



he air which are adapted to, and necessary for, the 

 mplification of the plant. 



Although the roots of a great majority of plants 

 are produced below the collet, or base of the stem, 

 hey may also be produced from almost every part of 

 he stem or branches, sometimes naturally, as above 

 alluded to, or accidentally, as in the case of a fallen 

 tree, or by art, as tak.es place in propagating by cut- 

 tings and layers. Of roots there are many modifica- 

 tions, differing chiefly in form, and probably in their 

 manner of acting as recipients of food. Bulbous- 

 stemmed plants have generally fleshy roots, with but 

 few fibres, acting in the earth as the air-plants and 

 other fibreless roots do in the air, viz., by absorption 

 through the pores of the cuticle. 



Some plants, as the peony, have, besides fibres, 

 large fleshy appendages, which not only serve to fix 

 them in the ground, but to serve as reservoirs of 

 moisture during severe drought. It seems to be 

 a general law of nature, that all plants assailable 

 by drought are furnished vith bulbous or tuberous 

 stems, or appendages to enable them to resist its 

 effects. 



In botanical books, roots are designated by proper 

 names viz., bulbous, of which there are three, the 

 scaly, the coated, and the solid ; to which are added 

 the duplicate, the articulate, and the caulinar. There 

 are also tuberous roots distinguished from each other 

 by their form, or by the manner of their connexion, 

 namely the globular, the truncated, the spindle-shaped, 

 the handed, the bundled and several others. The 

 writers who first proposed such distinctions, evidently 

 meant nothing further than that that part of the plant 

 usually found in, or resting on the ground is the root ; 

 because an onion or a potato can no more be called 

 the root than any other part of the stem which hap- 

 pens to be elevated in the air. The proper functions 

 of a root are to draw nourishment from and fix the 

 plant in the earth, neither of which are performed by 

 bulbs and tubers without the assistance of real roots 

 put forth from the body of the bulb or tuber, or from 

 a member quite distinct from what is called a bulb 

 or tuber. 



With regard to the permanency of roots, they 

 partake of the character of the plant to which they 

 belong. Those of annuals die with the plant at 

 the end of summer. The main roots of trees and 

 shrubs are as lasting as the stem and branches, but 

 the fibres produced upon them are more fugitive, in 

 many cases dying at the end of the growing season, 

 and renewed in the following autumn or spring. This 

 is very apparent in the case of bulbs and many tubers : 

 and it is worthy of remark, that there is much agree- 

 ment in the times of appearance and disappearance 

 of the leaves on the branches of a tree, shrub, or 

 herbaceous plant, and the fibres on the roots ; they 

 are produced simultaneously and fall off together. 



Compound plants, that is, such as perennial herbs 

 and some sorts of shrubs, being formed of many divi- 

 sions, have not a common root ; each division has 

 its own roots, and may be slipped off without injury. 

 Every new addition of shoots or leaves is produced 

 by a new set of working fibres. 



Some parasitical plants, as the misseltoe, have 

 no visible fibres ; their attachment to the plant 

 they live on, seems to be an union of the cellular 

 membranes of both. Others, as many of the tropical 

 orchidese, appear to use the stems of trees as sup- 



