72 



ESSENTIALS OF VEGETABLE PHARMACOGNOSY. 



CLASSIFICATION OF ROOTS- 



Roots may be classified as to their du- 

 ration, their order in time of development, 

 place or nature of origin, function, form 

 and consistency. 



As to duration we have roots divided 

 into two great classes, although the terms 

 designating them are in general applied to 

 the plant as a whole rather than to the 

 root, Monocarpous plants are those 

 which die after producing one crop of 

 fruit, Polycarpous those which produce 

 successive crops. The former are Annual 

 when they live but a single season— as the 

 rag weed and the sunflower; Biennial 

 when they devote the first season to the 

 storing up in some receptacle, such as 

 fleshy root or bud, a supply of nutriment 

 and fruit iu the second season. The term 

 winter-annuals has been applied to those 



fascicle of similar roots at length results, 

 as in the onion. In other cases the stem 

 of the plant takes root from one of its 

 nodes, the portion below this point (Fig. 

 363a), with the original roots, perishing. 

 To the cluster of roots thus resulting, al- 

 though they are really secondary, the term 

 "multiple primary" has also been applied. 

 A true multiple primary root is of rare oc- 

 currence and does not exist among drugs. 

 All roots which are not primary, or 

 branches thereof, and all branches of 

 roots which are not developed in regular 

 order' of succession, are called Adven- 

 titious. 



As 



* # 



_ - - ^_j ^ 



roots are Subterranean when they origi- 

 nate from points underground, whether 

 from root or stem, and Aerial when they 



I^A'!^.^.K^'« '?''' ^'^^ ^'1°^ "^^ }^^^r ''"Si^at'^ ^'^^ points above the snrface, 



part of the first season, fruiting early the 

 next season, so that their combined life 

 during the two seasons is less than twelve 

 months, as in the case of wheat and rye. 



whether from root or stem. A root may 

 originate from an aerial point and after- 

 ward fix itself in the earth, as the Brace- 

 roots of maize. A number of approxi- 



Such niay,_by being planted early in the mately equal and similar roots occurring 



season, finish their existence during one 

 season, as in the caae of spring wheat 

 Those monocarpous roots which devote a 

 number of years to the preparation for 

 fruiting, as in the case of the century 

 plant, belong to the Perennials. All Poly- 

 carpous roots belong, of course, to the 

 perennials. 



As to their order in time of development, 

 the first root developing from the radical 

 is the primary. Ail subsequently devel- 

 oped, whether from root or stem, are sec- 

 ondarj', although those developing from 

 secondary roots are sometimes designated 

 Tertiary and so on. If the primary root 

 continue its development so as to consti- 

 tute a branch-bearing axis, it is called a 

 Main-root or Tap-root (Fig. 362). If, in- 

 stead of so doing, it divide at once into a 

 number of approximately equal branches 

 it constitutes the so-called Multiple Pri- 

 mary Root. This term has, however, been 

 applied to a number of root clusters of 

 similar appearance, but of very dissimilar 

 origin. In some cases the primary root 

 continues its vertical growth but does not 

 increase in thickness to any appreciable 

 extent A number of similar roots then 



in a cluster, especially if they be fleshy 

 thickened, are denominated Fascicled, 

 Roots existing in the form of a mass of 

 thin, fibre-like, approximately equal and 

 similar elements are called Fibrous. 



As to their function roots are known as 

 Absorbing, Fixing or Storage roots. A 

 root of one kind may give origin to a 

 branch of a different kind. Absorbing 

 roots of parasitical plants are frequently 

 greatly modified in structure to form Hau- 

 storia. Fixing roots are usually desig- 

 nated as Rhizoids. Storage roots are usu- 

 ally much enlarged and possess a fleshy 

 consistency and characteristic forms. 

 When only a limited portion of a root is 

 fleshy-thicker? ed, so as superficially to re- 

 semble a tuber, it is called a Tubercle. 

 Care should be taken not to confuse this 

 technical meaning of the term with its 

 common use as designating a small tuber. 



As to their form, roots are Simple when 

 they do not branch, or Branched, Cylindri- 

 cal, Terete (which includes the cylindrical 

 and that form which differs only in that it 

 tapers), Tapering, Napiform, when taking 

 the form of a short, broad turnip (Fig, 



form 



develop near its point of origin so that a some radishes (Fig. 365), Conical, or Cone- 



