THE PLANT BODY. 107 



fies to its great abundance; for a brake is a dense tliickct (.r 

 undergrowth — as for example a cane '* brake." 



When fullj grown (P'ig. 44; the connnon brake has a leafy 

 top supported by a polished, dark-colored, erect stem, whicli in 

 New England rises to a height of from one to four feet above 

 the ground. In this climate, however, it appears to be some- 

 what undersized, for it grows to a height of fourteen feet in 

 the Andes,* and in Australia attains to twice the height of a 

 man, forming a dense undergrowth beneath tree-ferns 4n-l(n) 

 feet high.f In Great Britain it is from six inches to nine feet 

 high (Sowerbj), or even larger in exceptional cases. ''In drv 

 gravel it is usually present, but of small size; while in tliick 

 shady woods having a moist and rich soil it attains an enormous 

 size, and may often be seen climbing up, as it were, among the 

 lower branches and underwood, resting its dehcate pinnules 

 on the little twigs, and hanging gracefully over them." 

 (Newman.) 



General Morphology of the Body. 



The body of the fern, like that of the earthworm, consists 

 of cells, grouped to form tissues and organs. Their arrange- 

 ment, however, differs widely from that in the animal, for tlie 

 plant-body is a nearly solid mass, and there are no extended 

 internal cavities enclosing internal organs. The organs of the 

 plant are for the most part external, and arise by local modifica- 

 tions of the general mass. Like many higher plants the body 

 of the fern consists of an axis or stem-bearing branches, from 

 which arise leaves. The fern differs form ordinary trees, how- 

 ever, in the fact that the stem, with its branches, lies horiz(»ntal 

 beneath the surface of the ground. Only the leaves (fronds) 

 rise into the air. (Fig. 44.) It is convenient to describe the 

 body of the brake, accordingly, as consisting of two very (b*f- 

 ferent parts — one green and leaHike, which rises above the 

 ground; the other black and rootlike, lying buried in the soil. 

 These will henceforth be spoken of as the aerial and the muhr- 

 groicnd parts. 



The underground part lies at a depth of an inch to a foot 



* Hooker, I. c. 



\ Kroue, Botaii. Jahrcshericht, 1876 (4), 346. 



