200 VEGETABLE ORGANOGRAPHY. 



length exceeds that of the seed, they return by the 

 other side toward the base, and are then termed Peri- 

 pherical, as in the Spinach ; if they be still longer, they 

 may describe one and a half, two, or three turns, and 

 are then called Spiral, as in Dodorup.a. As to those 

 which are folded upon themselves, I cannot explain their 

 structure before having spoken of the parts of the 

 embryo. 



The Radicle (radicula) is that part which represents 

 the root ; in most Dicotyledons, it is presented in a 

 conical form, very like that of ordinary roots ; it goes 

 on gradually tapering from the neck to its extremity, 

 which is pointed ; at the period of germination it 

 elongates by its extremity, as other roots do during the 

 whole course of their lives, and makes lateral shoots, 

 but very slowly. To plants thus organized Richard 

 has given the name of Exorhize/e, because their 

 radicle is, as it were, projecting and developed : on the 

 contrary, in all Monocotyledons and some Dicotyledons, 

 as Berberis, Nuphar, &c, the radicle is thick and 

 rounded at the extremity ; it scarcely elongates at the 

 period of germination, but gives origin, either laterally, 

 or from its apex, to some usually simple little roots, 

 which act the part of radicles, and sometimes seem to 

 issue out of the round radicle by particular slits ; this 

 structure has caused Richard to give to plants, thus 

 organized, the name of Endorhize^;. This has been 

 for a long time observed in Wheat, Rye, and Barley, 

 and more attentive observation has proved that a great 

 number of other plants partake of the same structure. 



It frequently happens in the embryos of the Endor- 

 hizeEe, either that the radicle, from which the little 

 roots ought to proceed, is very thick, and, as it were, 

 capitate, and the\| the embryo is said to be Macro- 

 podous, as in Pekea ; or, that one of the lateral parts 



