Embryo of Botrychium obliquum , Miihl. 153 
pushing through the soil, it appears above ground as a small ternate leaf, 
with a long slender petiole (Fig. 7). 
The venation of the leaf-lobes is dichotomous, and suggests that the 
ternate form of the lamina is due to an unequal dichotomy such as can 
often be seen in many ferns in the early leaves intermediate between the 
Text-fig. 9. A. Two longitudinal sections of a young sporophyte, showing the arrangement 
of the vascular bundles, x about 70. B. Two sections of a somewhat older sporophyte, show- 
ing second and third leaves, L 2 , L 3 . 
dichotomously lobed cotyledon and the pinnate leaves of the older sporo- 
phyte. 
The position of the young sporophyte, with reference to the gameto- 
phyte, is exactly the same as in the Marattiaceae, the bipolar sporophyte 
completely perforating the gametophyte, the cotyledon emerging above, the 
root below. It must be remembered, however, that in the Marattiaceae, as 
in the ordinary ferns, the archegonia are upon the ventral surface of the 
prothallium instead of upon the dorsal side, as is the case in Botrychium. 
