THE YOUNG SPOROPHYTE 



149 



The cotyledon in Kaulfussia (fig. 123) is spatulate in form and not unlike that 

 of Daneea in shape and also closely resembles in outline the broader leaf forms of 

 Ophioglossum moluccanum. The resemblance to the latter is much increased by 

 the venation, which is reticulate and extraordinarily like that of the cotyledon of 

 Ophioglossum. As in Ophioglossum, there is usually a mid-vein, but this is not, 

 however, noticeably thicker than the laterals. The latter, instead of extending 

 free to the edge of the leaf, are connected at their distal ends with the mid-vein so 

 as to inclose more or less elongated areoles. The central vein does not extend to the 

 tip but, as in Datura, divides into equal branches which join above so as to inclose 



a fi 



Fir.. 127. 



A. Lamina of young cotyledon of Marattia douglasii. 



B. Section of lamina of cotvledon. X300. 



X260. 



a terminal areole. A careful examination of the secondary veins shows that their 

 divisions are really dichotomous, as in the lateral veins of the other Marattiacea?, 

 and some of the ultimate branches may reach the margin of the leaf, or more rarely 

 they may end freely within the areoles. 



As the cotyledon develops there is more or less elongation of the petiole, which, 

 however, very seldom exceeds the lamina in length. The petiole is usually more or 

 less deeply channeled upon its inner face. In Marattia douglasii (fig. 133) the base 

 of the cotyledon is much enlarged just above the level of the stem apex, which is 



Fig. 12S. 



A. Section of lamina «<!* cotyledon of Kaulfussia, traversing one of the large stomata, <t. ■, too. 



B. A young stoma. 



C. An older one. 



thus almost inclosed in a sort of cleft in the base of the cotyledon, very much as it is 

 in the case of Botrychium or Helminthostachys. In Angiopteris there is but slight 

 contraction at the base and the stem apex forms a strongly oblique surface, hardly 

 covered at all by the base of the cotyledon. The base of the cotyledon is still more 

 conspicuously hollowed out in Datura and especially in kaulfussia (figs. 136, 137), 

 and in the latter there is a circular ridge completely surrounding the stem apex, 

 exactly as is the case in the young bud in Ophioglossum moluccanum. I races of 

 this ridge can be seen also in Datura and Marattia, but this is much less conspicuous 

 than in Kaulfussia. In the latter this cavity is especially marked, so that one might 

 almost speak of a stipular sheath, and this resemblance to Ophioglossum in the 



