xix] 



ANATOMY 



6i 



out any endodermis. Near the base of the stock the vascular ring may 

 appear more complete, but higher up the disrupted stele appears as a ring 



A B 



Fig. 354. Ophioglossittn Bergiaiut/u Schlecht. A, transverse section of the stock, showing a semi-lunar 

 stele, with a wide foliar gap into which a small leaf-trace is entering. B, another section showing 

 probably the result of overlapping of the foliar gaps. No endodermis is seen. ( x 200.) 



of meristeles embedded in parenchyma (Fig. 354). It is, in fact, a rudimen- 

 tary type of dictyostele. In some species the stock is distended for storage, 

 as in O. palmatum (see Vol. I, Fig. 36). Here the vascular structure has been 

 found to follow the same scheme 



as that described, but it is em- 

 bedded in massive parenchyma 

 (Fig. 355). In this species, how- 

 ever, and also in O. pendidimi 

 and simplex, the structure is fur- 

 ther complicated by the fact that 

 the leaf-trace is divided from the 

 first, while endogenous roots may 

 traverse both pith and cortex 

 (Fig. 356). (See Bower, y^//;/. of 

 Bot. 191 1, p. 227.) These facts 

 indicate that Ophioglossiim, and 

 in particular O. palmatum, pen- 

 dultim and simplex, possess the 

 most advanced type of stelar 

 structure in the Family as judged 

 by the usual criteria of compari- 

 son for Ferns. As bearing on the 

 question of origin of the pith in 

 these plants the record of strands 



(^ 



rr\ 



\ 



10 



7 





A 





^^^. 



V 



8 



Fig- 355- Vascular system of the distended stock of 

 Ophioglossuni palmatum : the endogenous roots are 

 omitted for clearness. The leaf-traces are numbered, 

 and the marginal strands are connected by dotted 

 lines. Only the marginal strands are represented in 

 leaves 8, 9, 10. (Enlarged.) The leaf-traces come off 

 as two separate strands, dividing up later, and the 

 resulting strands arrange themselves in a circle in 

 each petiole. 



