38 



THE OPHIOGLOSSALES 



In 0. moluccanum the prothallium probably lives for a single season only, and 

 the formation of the sporophyte stops its further development; but in O. pendulum, 

 where embryos are much less frequently found, the large gametophyte continues 

 its growth apparently unchecked by the development of the attached sporophyte, 

 which retains its connection with the gametophyte for a very long time, as in O. 

 vulgatum and Botrychium virginianum. 



The embryo reaches a very large size before it breaks through the prothallium. 

 The primary root then emerges as a conical point (fig. 3, F, sp). The second root 

 remains short for a time. There seems to be a good deal of diiference as to the time 

 of the appearance of the latter. In the globular type of embryo the second root 

 appears very early, and it looks as if it might have been formed quite independently 

 of the primary root. Sometimes, however, the primary root may attain a length of 

 several centimeters, and may even begin to form rootlets before the second root 

 emerges; while in other cases the two roots grow in opposite directions and seem to 



be of about equal size (fig. 3, E). 



The leafy shoot in Ophtoglossum pendulum 

 does not appear until the root system is well 

 advanced. The primary root, although attaining 

 a length of 10 centimeters or more, in no cases 

 showed any signs of leaf-bearing buds in the 

 specimens that I collected. Rootlets were devel- 

 oped in some cases, and it is not impossible that 

 there may be an extensive development of the 

 root system before the first leafy bud is formed. 

 This is quite in harmony with the large develop- 

 ment of the roots in O. vulgatum, where Bruch- 

 mann believes that it may be eight or ten years 

 before the first foliage leaf appears above the 

 ground. In O. vulgatum., however, this leaf arises 

 from the original stem apex derived directly from 

 the embryo, and not from an adventitious bud. 

 Ophioglossum moluccanum and the similar 

 species that grow with it differ very much from 

 Ophtoglossum pendulum in the character of the 

 young sporophyte, which, as we have seen, at once 

 develops a green foliage leaf or cotyledon. The 

 sporophyteveryclosely resembles that of O./jfJwn- 

 culosum described by Mettenius; in fact, the 

 resemblance is so close that it would seem to 

 confirm the close relationship of this species and 

 possibly its identity with some of the forms asso- 

 ciated by Raciborski under the name O. moluccanum (Raciborski 1). 



As Mettenius correctly showed in 0. pedunculosum, the first organ to be 

 developed is the cotyledon, which soon pierces the earth and appears as a green 

 foliage leaf This primary leaf is continued directly into the primary root, but no 

 stem apex is developed, nor is any sheath formed about the leaf base in the young 

 sporophyte, which consists practically of leaf and root alone. The latter often 

 penetrates for some distance into the prothallial tissue before it emerges, so that the 

 central portion of the young sporophyte is surrounded by a sheath formed by the 

 prothallial tissue. A longitudinal section of the sporophyte (fig. 22, A) shows that 

 the tissues of the leaf are continued directly into those of the primary root. A 



Fig. 22. — Ophioglossum moluccanum, 



A. Median section of young sporophyte before 



formation of bud; /, cotyledon j r, root. 

 prj the gametophyte. X15. 



B. Central region of same, more enlarged; /r, 



first tracheids. 



C. An older sporophyte, showing bud, b, de- 



veloping from primary root. X15. 



D. E. Lamina of cotyledon, showing venation. 



X3. 



