. Carnegie Institution of Washington publication. THE OLDER SPOROPHYTE 183 hairs, which resemble those in Dancea in being multicellular. In the larger roots there may sometimes be five or six cells, each with a conspicuous nucleus, making up these root hairs, and sometimes they show signs of branching at the apex. It is evident that in Kaulfussia, up to the time that five leaves have developed, the vascular system of the stem consists of a single axial strand, a sort of sympodium formed by the completely united traces of the young leaves. The xylem may appear as a single mass at the points whe
. Carnegie Institution of Washington publication. THE OLDER SPOROPHYTE 183 hairs, which resemble those in Dancea in being multicellular. In the larger roots there may sometimes be five or six cells, each with a conspicuous nucleus, making up these root hairs, and sometimes they show signs of branching at the apex. It is evident that in Kaulfussia, up to the time that five leaves have developed, the vascular system of the stem consists of a single axial strand, a sort of sympodium formed by the completely united traces of the young leaves. The xylem may appear as a single mass at the points where fusion of the leaf traces is complete, but at most points the individuality of the component strands is maintained, so far as the xylem is concerned. Figure 168 shows transverse sections from a much older sporophyte. The section of the petiole still shows the single vascular bundle having near its inner face a single large mucilage duct, which follows the leaf trace downward into the stem. As the bundle from the leaf enters the stem it broadens, and there is a separation of the xylems into two masses, first seen in the fourth leaf. In the specimen shown here the earliest leaves were not sectioned, and, as it can not be stated exactly how many leaves the young sporophyte had developed, it must therefore remain uncer- tain which leaf first shows the completely divided leaf trace. In the specimen in question the oldest leaf that showed had a single trace with two separate xylems,. Fig. 167.—Three longitudinal sections of an older sporophyte of Kaulfusiia. X25. while the next leaf had the leaf trace completely separated and resembling a corre- sponding stage in Dancea (fig. 168, /"). As the traces from the two leaves approach preliminary to their fusion, the double leaf trace has its parts united again so that the traces become single before they join. The leaf trace now forms a single bundle, crescentic in section and very much like the single broad leaf trace from the e
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