42 



PTEROID FERNS 

 I' 



[CH. 



Fig. 606. Voung plant of Pteridniin aquiliniiin (L.) Kuhn, seen 

 from the convex side (obliquely downward directed) of the curved 

 primary axis, and showing the first dichotomy, with downward 

 directed shanks, a' = primary axis; (^?" = shanks of first dichotomy; 

 /' = leaves borne on the primary axis : /" = leaves borne on shanks of 

 dichotomy; ;•' = roots attached to the primary axis; r'^ = roots on 

 shanks of dichotomy. 



Fig. 607. Pteridium aquilimivi. Vascular system of a node seen from the dorsal side, 

 somewhat simplified. The internal system and lateral folds of the leaf-trace are darkly 

 shaded. A portion of the dorsal meristele of the outer cylinder is cut away to show 

 branching of the internal strands. (r.j'. = compensation strand. (After Tansley and 

 Lulham.) 



