194 



OUTLINES OF PLANT LIFE. 



spni 



upon the sexual stage, with which it is connected throughout 



its entire existence (^ 60). In 

 the fernworts and seed plants, 

 however, the sporophyte pos- 

 sesses extensive nutritive tissues, 

 the leaves, stems, and roots be- 

 longing entirely to this stage. 

 Sporangia in these plants may 

 be formed either upon the stem 

 or the leaves — never upon the 

 roots. 



274. Liverworts and mosses. 

 — In most liverworts and mosses 

 the spore case is developed within 

 the enlarged upper part of the 

 sporophyte, to which the name 

 capsule is given (figs. 46, 148, 

 and \ 59). By the time the 

 spores are mature the capsule 

 has become filled with the loose 

 spores. It bursts at the top or 

 opens by the falling off of the 

 lid-like upper end, and thus 

 allows the spores to escape. 



275. Ferns. — In the ferns the 

 sporophyte phase is the plant 

 with roots and leaves. The 

 spore cases are either produced 



Fig. 148. — Longitudinal section of tiie 

 youngcapsule of atrue moss(^rj/M'«). 

 J, spore case. At this stage the motiier 

 cells of the spores, j/7W, nave become 

 free (only a few are shown, still en- 

 closing the spores, which are later re- 

 leased! ; jw, the wall ot - the spore 

 case, hned by the remains of another 

 layer of cells now disorganized ; c, the 

 columella, of partly collapsed cells ; 

 r'j, intercellular space; cw, wall of 



the capsule ; nn, the annuius, a ring upon the under Surface of the 



of cells which pries off the lid, at '■ 



whose edge they develop ; ot, the foliage leaves or upon Specialized 



outer, wz, the inner peristome, formed " ^ * 



by the thickening of parts of the walls leaves. They are usually numer- 



of certain rows of cells ; nt, nutntive ■' ^ 



tissue, with chioropiasts and intercei- qus. Stalked, free, and often as- 



lular spaces. Magnified 25 diam. — 



Original. sociated in clusters. The clus- 



ters are often arranged in elongated groups or lines (fig. 149). 



