VII 



PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACE^ 261 



g^iophore not yet differentiated. At the base of the young-est 

 leaf is the stem apex. Th& whole bud is covered in this s[)ecies 

 with numerous short hairs, wdiich are also found in B. tcrnatiun 

 and some other species ; but in B. sunplcx and the other simpler 

 species it is perfectly smooth, as in Ophioglossuiii. The young 

 leaves in B. Virginianuni are bent over, and the segments of the 

 leaf are bent inward in a w^ay that recalls the vernation of the 

 true Ferns. The sporangiophore grows out from the inner 

 surface of the lamina, and its branches are directed in the 

 opposite direction from those of the sterile part of the leaf. 



B. 



Fig. 142. — Botrychium Virginiamim. A, Rhizome and terminal bud of a strong plant, 

 the roots and all but the base of the oldest leaf removed, X i ; B, longitudinal sec- 

 tion of the bud, X3; St, the stem apex; 1/ II. III., the leaves; C, transverse sec- 

 tion of the petiole, X4; D, transverse section of the rhizome, X about 16; P, 

 the pith; m, medullary rays; x, xylem; c, cambium; ph, phloem; sh, endodermis. 



The vascular bundles of the stem are much more prominent 

 than in OpJiioglossurn, and form a hollow cylinder, with small 

 gaps only, corresponding to the leaves. This cylinder shows 

 the tissues arranged in a manner that more nearly resembles the 

 structure of the stem in Gymnosperms or normal Dicotyledons 

 than anything else. Surrounding the central pith (Fig. 142, P) 

 is a ring of woody tissue (x) with radiating medullary rays 

 (m), and outside of this a ring of phloem, separated from the 



