30 



THE HABIT x^ND THE HABITAT OF FERNS 



[CH. 



strength of the stem, which does not increase by cambial activity, but is 

 entirely primary in such Ferns. Nevertheless it derives additional support 

 from the mass of adventitious roots which surround it, and often give it the 

 appearance of thickening towards the base (Frontispiece). The dendroid 



Fig. 36. Whole plant of Ophioglossiim palinatiim showing the distended 

 storage-stock, from a drawing by Prof. Lawson. (g nat. size.) 



habit being thus the simple result of continued apical growth, it may be 

 assumed by Ferns of various affinity. It is seen in a dwarf form, though 

 sometimes attaining considerable height, in Osiminda and Todea ; in BlecJi- 

 num, Sadleria, and Brainea: also in Thyrsopteris. It attains full development 



