CHAPTER I 



THE LIFE-HISTORY OF A FERN 



The present volume will treat generally of the Plants included in the Class 

 of the Filicales, or as they are commonly called, the Ferns. Any such treatise 

 must take as its starting point a knowledge of the usual structure and suc- 

 cessive phases of life of the plants in question. Experience shows that the 

 cycle of life is uniform in its essentials for all normal Ferns, while its features 

 correspond also to those seen in land-living plants at large. That life-cycle 

 comprises two alternating phases, or "generations." The one is the relatively, 

 large leafy plant popularly recognised and designated as the "Fern-Plant": 

 the other is a relatively small and simple green scale-like structure, called 

 the "Prothallus." The relation of these to one another, and the constant 

 alternation which they show, are best illustrated by a description of the 

 successive incidents seen in the life-history of some common Fern. The 

 familiar Male Shield Fern {Diyopteris {Nephrodiuin) Filix-vias, Rich.) will 

 serve as a suitable example. 



This Fern is known to everyone as growing in woods and hedgerows, 

 and even in more exposed situations, such as open gills and hill-sides of 

 higher-lying districts (Fig. 31, p. 26). It presents a robust appearance, and 

 when fully developed it consists of a simple shoot with an oblique and 

 massive stock, which is relatively short. This is entirely covered over by 

 the bases of the leaves, of which the youngest form a closely packed terminal 

 bud (Fig. I, A, D). Those leaves which are seated further from the apex, 

 and immediately below the terminal bud, may in summer be found to be of 

 large size and complex structure (Fig. 2). Collectively they form a crown- 

 like series surrounding the apex of the stem that bears them. Passing again 

 further back from the apex of the stem, the surface is found to be closely 

 invested by the bases of the numerous leaves of former seasons, the upper 

 portions of which have rotted away. Clearly then the leaves are borne upon 

 the stock in acropetal succession. While young they are densely covered by 

 chaffy flattened scales, which take a rusty colour with age; but they mostly 

 fall away from the mature leaf, though often persisting on its stalk (Fig. 2). 

 If the plant be dug up, and the soil be carefully removed from it, an ample 

 root-system will be seen, consisting of thin, wiry, and dark-coloured fibrils, 

 which spring from the basal parts of the leaves. 



B. I 



