THE ROOTS OF VASCULAR PLANTS. 219 



simple and rather thick ; they have almost all their spon- 

 gioles united into a single bundle at the extremity of 

 the cone, and the cellular tissue of the bark is generally 

 much dilated ; they branch but little or not at all, and 

 only bear here and there some fibrils, which are fre- 

 quently entirely absent. They are called collectively, 

 sometimes by the too vague name of Tuberous Roots, 

 sometimes bv the too restricted one of Fusiform 

 Roots, and more correctly by that of Spindle-shaped 

 ( Pivotantes ) , which makes allusion to their constant 

 vertical direction; such are, for example, the roots of 

 the Carrot, Turnip, Scorzonera, &c. The Bistort only 

 differs from this class in having the principal trunk 

 curiously twisted. 



We may distinguish among simple roots two varieties 

 of form: — 1st, Fusiform Roots properly so called, or 

 those which are nearly in the form of a spindle ; such 

 are those of the CaiTot, &c., which have the form of 

 an elongated cone. 2d, Turnip-shaped Roots, or 

 those which are very much swollen out under the neck, 

 and abruptly taper to an elongated point; such are 

 those of the Turnip, the Turnip-Radish, &c. The ex- 

 amples of the different varieties of Radish prove, that 

 this form hardly differs from the preceding. 



Roots which have several points of origin near the 

 neck present also several distinct varieties of form: — - 

 1st, There are some, as those of Grasses, each fibre of 

 which, distinct and simple at its commencement, so 

 ramifies, that the divisions of each of them resemble the 

 fibrous roots of the preceding class ; the name fibrous 

 has also been given to them, but it must be remarked, 

 that under this denomination, roots of two classes are 

 confounded. 2d, Several of these compound roots 

 shoot from their neck simple cylindrical fibres, which 

 descend, either remaining parallel, or slightly diverging ; 



