THE ADULT SPOROPHYTE 



95 



leaf trace, but pass downward through the cortex separately, and even if it were 

 possible to make a satisfactory series of the sections of the large rhizome the task of 

 following the course of the very numerous individual bundles would be a difficult 

 one. From free-hand sections of the large base of the leaf, however, one can see 

 without difficulty the general plan of the vascular skeleton. The stout petiole is 

 slightly contracted at its base, but a section presents very much the same appear- 

 ance as one made higher up. 



In specimens that have been preserved in alcohol so as to become decolored, 

 the tissues of the thick leaf base are sufficiently transparent to show quite clearly 

 the course of the bundles even without sectioning, by simply slitting the petiole 

 through the middle. The bundles are seen to anastomose freely at the extreme base 

 of the leaf, very much as they do in the lamina. If such a section is examined where 

 the leaf base joins the rhizome (fig. 63, D) the circle of bundles can be seen to become 



Fig. 63. — Ophfoglossum pendulum L. 



A. Stem showing dorsiventral form and branched roots. /, bases of leaves. 



B. Buds attached to a root fragment. The older bud, h^ , has developed a young sporophyll, sp^ and two secondary roots. 



C. Base of a large leaf, showing arrangement of vascular bundles. 



D. Section of same. 



smaller as the bundles enter the cortex, but the bundles remain for the most part 

 quite separate, although there may be an occasional anastomosing of these, as occurs 

 in the petiole itself. This group of bundles composing the leaf trace — if such it 

 can be called — forms a circle about the opening in the vascular cylinder of the stem 

 where it joins the latter. A section of the vascular cylinder within the rhizome itself 

 presents the appearance of a nearly complete ring, which is probably formed by fus- 

 ing of the bundles derived from the leaf bases. The much greater development of 

 woody tissue in the stem of O. pendulum as compared with that of Euophioglossum 

 is doubtless due to the very much larger size of the leaves and the correspondingly 

 greater number of vascular bundles contributed by them to the woody cylinder of 

 the rhizome. 



The very young leaf, such as is shown in fig. 63, B, has a thick, fleshy leaf base, 

 terminating in a very small and pointed lamina strongly bent over as it is, e. g., 

 in the young leaf of Botrychtum virginianum. This difi^ers from the species of 

 Euophioglossum, in which the leaf is straight in the bud. Under the arching hood 

 formed by this folded-over lamina is the young spike, almost equal in length at this 

 time to the lamina itself. A somewhat older stage is shown in fig. 82, B. The 

 leaf has now become somewhat flattened, but as yet there is no sharp distinction 

 between the lamina and the petiole. In this early stage of development the inter- 

 pretation of the spike as a terminal structure seems very plausible. An interesting 



