. Carnegie Institution of Washington publication. 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 o
. Carnegie Institution of Washington publication. 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 th
Size: 2217px × 1128px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1910, bookyear1911
