THE PINNA-TRACE IN THE FERNS. 



355 



long in Leptopteris hymenophylloides and in Osmunda javanica, Bl., quite short in 

 O. regalis, L. The pinna-traces of Leptopteris hymenophylloides and Osmunda 

 regalis are wide ; those of Todea barbara (L.) Moore and 0. javanica are narrow. 



The Schizaeaceae, in contrast, invariably supply their pinnae in the marginal 

 fashion. In Lygodium circinnatum (Burm.) Sw. and L. scandens (L.) Sw., the leaf- 

 trace is unincurved and the supply is quite directly marginal. It is so also in Mohria 

 caffrorum (L.) Desv. The hooked leaf-trace already described for Aneimia hirta is 

 found also, though less prominently, in Aneimia collina, Raddi (PI. XXXIII. fig. 4), 

 while slight hooks also appear in A. phyllitidis (L.) Sw. and A. rotundifolia, Schrad. 



In all of these the pinna-trace goes off marginally. 



The third family of the Simplices — the Gleicheniaceae — is consistently extra- 

 marginal in supplying its pinnae. Boodle ('01) and Bower ('12) have described the 



Text-Fig. 3. — Gleichenia Jiabellata, R. Br. Diagrammatic representation of the changes occurring in the 

 vascular system of the petiole during the liberation of the pinna-traces. 



pinna-traces of Gleichenia dicarpa, R. Br., var. longipinnata, G. Jiabellata, R. Br., and 

 G. linearis (Burm.) Clarke. In Gleichenia Jiabellata (PI. XXXIV. fig. 14) the incurved 

 margins become nipped off from the rest of the leaf-trace on its inner side, round 

 themselves into little rings of tracheides, and run up isolated from the main part of the 

 trace for some distance. The back of the remaining hook separates off to go to the 

 pinna, and then these isolated circles open out on their abaxial sides and re-form the 

 leaf -trace by extending to meet its margins (text-fig. 3). In Gleichenia rwpestris, 

 R. Br., the margins of the leaf-trace separate off when the pinna-traces are being- 

 given off, but here they do not form two rings but only a couple of arcs with the 

 concave sides towards the centre of the petiole. They may even become attached 

 to each other by their margins. In Gleichenia circinnata, Sw., var. speluncse, the 

 pinna-supply is of the normal extramarginal type ; almost no gap occurs in the 

 tissues of the leaf-trace when the pinna-trace is given off. 



The method of supply in Gleichenia Jiabellata and G. rupestris may be regarded 

 as a special variety of the type seen in the Osmundaceae, as long gaps are thus formed 

 in the leaf-trace opposite to each pinna. 



Passing to the Gradatae, we find the extramarginal type prevails. In the 



