FTLICALE? A' 



But the vast majority live in moist and often in shaded positions, 

 and, as will be seen later, external liquid water is necessary for the 

 completion of the normal cycle of their life. The Fern Plant is with 

 very few exceptions perennial. It consists of a shoot which may or 

 may not be branched, and is attached to the soil by numerous fibrous 

 roots. The shoot consists of axis and leaves, as in the Flowering 

 Plants, but usually without axillary buds. The leaves are large in 

 proportion to the stem that bears them. Often they are highly 

 branched, with two rows of lateral pinnae that are branched again 

 repeatedly. This, together with their delicate texture, gives the 

 feathery appearance to the leaves of most Ferns (Fig. 373). It is 

 specially conspicuous in the large Tree-Ferns, where each leaf may 

 be many feet in length. This habit (megaphyllous) contrasts strongly 

 with that of the Lycopods with their small unbranched leaves 

 (microphyllous). 



The Coal Period has been sometimes described as ' The Age of Ferns." It 

 is true that large-leaved Fern-like Plants were frequent then. But many of 

 these have been lately shown to have been Seed-bearing Plants (Pteridosperms), 

 whereas Ferns have no seeds. The question has then been raised whether 

 true Ferns existed at all at that early time. There are at least three types 

 which can only have been Ferns that did live then, and Botryopteris, of which 

 the stele is shown in Fig. 375, is an example. Some Ferns resembling these 

 early fossils survive to the present day. But many of the Ferns we know are 

 relatively modern. It is doubtful whether at any time a more varied Fern- 

 Flora has existed on the earth than at the present day. If that be so, the 

 present is as much the age of Ferns as any that has gone before. 



The Ferns show a comparatively primitive cycle of life. It consists 

 of two alternating and physiologically independent phases, or genera- 

 tions, the one diploid (non-sexual), which is the sporophyte, the 

 other haploid (sexual), which is the gametophyte. The former is what 

 is known commonly as the Fern-Plant ; the latter is a small green 

 scale-like body, which is called the Prothallus. As the former is the 

 better-known phase, it will be described first. 



Male Shield Fern and Bracken. 



The large-leaved shoot of the Fern Plant may grow upright, and 

 usually unbranched, as in Tree-Ferns, and the Royal Fern (Osmunda) ; 

 or obliquely, as in the common Shield Fern (Dryopteris) (Fig. 374. A) ; 

 or horizontally with a creeping habit, as in the Bracken [Pteridium) 

 or the Common Polypody. When upright, the internodes are short, 

 and the numerous leaves take that basket-like grouping so well seen 



