THE YOUNG SPOROPHYTK 



69 



Botrychium virginianum, the lamina, which although very greatly reduced never- 

 theless is present, is bent over sharply against the stout petiole, which is strongly 

 convex on its adaxial side. In the specimen figured there was no trace of a stipular 

 sheath developed in the cotyledon, but sometimes this is very well developed, 

 although the upper part of the cotyledon remains quite rudimentary. The little 

 cotyledon has the rudimentary lamina distinctly ternate in outline and very much 

 resembles some of the rudimentary early leaves found in Botrychium lunaria, as 

 figured by Bruchmann. A single vascular bundle extends through the petiole of the 

 cotyledon, nearly to the base of the lamina, but except in the basal region the 

 development of the xylem is m;;ch reduced and is entirely lacking before the lamina 

 is reached. The bundle of the cotyledon, where it bends at the base into the inter- 

 node, is nearly as well developed as the bundle of the second internode which 

 separates from the former just below the insertion of the cotyledon. On the opposite 

 side of the second internode from the cotyledon, and extending downward through 

 the first internode for a short distance below the level of the cotyledon, there is seen 



c6t 



l'h,. 46. 



A, B. Two longitudinal sections of a young sporophyte of Helminthostaehys; pr, gametophyte. X6. 



C. Upper part of same, more enlarged; b, terminal bud; cot, cotyledon; /, lacuna in first internode. 



D. Apical region. / J , third leaf; sc, epidermal scales. X140. 



E. Tracheids showing bordered pits and thickened bars. X320. 



in the specimen figured a large lacuna, separated from the outside of the internode 

 by about halt a dozen layers of cells and on its inner side from the endodermis of the 

 stele by two or three layers of cells. This lacuna, as Lang pointed out, is not always 

 present. At the upper end of the second internode can be seen the base of the second 

 leaf, the stipular sheath of which incloses the young bud at the summit of tin axis. 



On its inner (dorsal) side the terminal bud shows the young third leaf, opposite 

 which is the section of the ridge surrounding the small free surface of the stem apex, 

 very much like the condition in the young bud of Ophioglossum moluccanum. 

 I he form of the young leaf at this stage is more like that of Botrychium lunaria than 

 that of B. virginianum. The young leaf is a blunt cone with a marked projection 

 on its inner side, extending over the apex of the stem and marking the beginning 

 of the stipular sheath, which is entire as in H. lunaria, and not divided into two free 

 stipules as in B. virginianum (fig. 4.6, D). A conspicuous strand of procambium 

 extends into the leaf and joins the trace of the second leaf. As in Botrychium and 

 Ophioglossum, the stele of the internode does not extend upward beyond the base of 

 the \-oungest leaf and then is no indication that it derives any of its tissues directly 



