176 Roots. 



roots, merely adapted for absorption from the soil ; they resem- 

 ble, in shape, the inverted branches of a tree : such are mustard 

 barley, peas, beans, cucumbers : see fig. 43. 



The second class, from their accumulation, swell out into 

 various shapes ; those of the carrot are a common example, fio-. 

 44; the reservoir being in the main trunk. 



The third class have many forms, the rose, geranium, <fec. 

 are examples. Many of them become annual by transplantation 

 into cold climates, and vice versa. 



Fig. 39 shows a scaly bulb, as in the white lily. Fig. 40 a 

 solid bulb, as in the crocus. Fig. 41, Transverse section of a 

 coated bulb. Fig. 42, a tubulous and pendulous root, as in the 

 peony. Fig. 45, a creeping root. 



Fig. 35 shows the seed of a bean split in two ; A A are the coty- 

 ledons or seed-leaves, to afford sustenance and protect the germ. 

 d Is the plumula or ascending axis, which is finally developed 

 into a stem on which the leaves and fruit are formed, e The 

 descending portion or root, which we have already described. 

 b Is the plant itself, in miniature. The point of union of the 

 ascending and descending axis, the crown or neck ; it is also 

 sometimes termed the collar. The name cotyledon comes from 

 the Greek, kotule, a cavity. The number of these varies in differ- 

 ent plants ; all having two are called Dicotyledons, like the bean ; 

 if but one, they are Monocotyledons, as the grasses and lilies. If, 

 as in the case of the mosses, we cannot trace any seed-leaves, 

 we term them Acotyledons. There are, sometimes, though 

 rarely, plants having more than two, to which the name of Poly- 

 cotyledons is applied. As the number of these seldom varies in 

 the same family, they have been assumed as a ground of classi- 

 fication by many botanists. An ancient botanist remarks, that 

 the embryo continues imprisoned within its seed, and remains 

 in a profound sleep, until awakened by germination, it meets 

 the light and air to grow into a plant similar to its parent. If, 

 therefore, the simple laws upon which plants are constructed are. 

 kept in view, they will afford a ready explanation of all the 

 diversities exhibited by vegetables. 



