THK YOUNG SI'OROPHYTK 



159 



In Dancra a dozen or more leaves may be formed before there is any branching 

 of the lamina. While the cotyledon may show an approach to the pinnate venation 

 of the older leaves, there is almost always a dichotomy of the apex of the slender 

 midvein, and this is generally true also for a number of the subsequent leaves, 

 although in these later leaves the midrib becomes well marked and the lateral veins 

 are developed apparently monopodially. In D. simplicifolia the leaves remain 

 permanently unbranched, but in all of the other species the later leaves are once 

 pinnate. The intermediate leaves have the ternate form found in Marattia and 

 Angiopteris, and after a few of these, about two or three, have been formed, five 

 foliate leaves appear and the number of leaflets gradually increases, as new leaves 

 are formed, until the full number of leaflets is developed. The early ternate leaves 

 often have the terminal leaflet much larger than the lateral ones, and the leaf 



Fig. i 



1-5. Transverse sections from a series of a young root of Danaa jarnaicrnsis. 2 shows apical cell. 

 6. Section of bundle fr&m fully developed primary root, en, endodermis. 



closely resembles the corresponding stages in Angiopteris. The petiole in most 

 species is more or less obviously winged. In Dancea the stipules are (sometimes, at 

 least) not formed until the fourth leaf. In the fourth leaf (fig. 126, B), however, 

 they are well developed, appearing as two conspicuous wing-like organs with 

 senate edges. 



In all of the genera there is a root formed for each leaf in the earlier stages of 

 the sporophyte, but how late this continues was not determined. In the older 

 sporophyte more than one root may be formed for each leaf. In Kaidfussia the 

 second root is developed earlier than in the other genera, beginning to develop while 

 the second leaf is still very small, and in general the roots in Kaulfussia seem to 

 develop earlier than in the other genera. The second root is especially late in 

 developing in Duntea, the very first rudiment of the root making its appearance 

 between the first and second leaves, after the latter is already quite well advanced. 



