. Carnegie Institution of Washington publication. THF OLDER SPOROPHYTE 203 twenty xylem rays, only the outer tracheids being lignified. In the plant which was examined by Miss Shove only the earth roots were found, and these, instead of having only five xylems as Russow asserts, had from ten to thirteen and the xylem elements were entirely lignified. The probabilities are that there is no sharp line to be drawn between the aerial roots and the earth roots. Figure 183 shows a sec- tion of a root from the base of a small plant from Australia, in which there were fourteen xylem masses. As will be
. Carnegie Institution of Washington publication. THF OLDER SPOROPHYTE 203 twenty xylem rays, only the outer tracheids being lignified. In the plant which was examined by Miss Shove only the earth roots were found, and these, instead of having only five xylems as Russow asserts, had from ten to thirteen and the xylem elements were entirely lignified. The probabilities are that there is no sharp line to be drawn between the aerial roots and the earth roots. Figure 183 shows a sec- tion of a root from the base of a small plant from Australia, in which there were fourteen xylem masses. As will be seen, there is the same circle of large mucilage ducts and the tannin cells that are found in the root of Marattia, which it very closely resembles. Root hairs are nearly or quite absent, in which respect these resemble the older roots of other Marattiaceae. In two cases Miss Shove found a dichotomous branching of the root. This, while probably anomalous, is interesting, as it recalls the method of branching in the roots of Ophioglossum. ARCHANGIOPTERIS. The genus Archangiopteris, with a single species, A. henryi Christ and Giesen- hagen, is at present known only from a single locality in southern China. Arch- angiopteris in habit resembles a large Dancca. The leaves, which reach a length of. Fig. 183.—Angiopteris. A. Section of a large root. mt mucilage ducts. X14. B. Part of the central cylinder of the root, en, endodermis. X70. about a meter, have from seven to twelve leaflets, much like those oiDantea elliptica, both in form and venation. The stalk of each leaflet is swollen in a manner that suggests the nodular swellings in the petiole of Datura elliptica (fig. 184). The only account of the structure of the plant is that of Gwynne-Vaughn (Gwynne-Vaughn 2), but as he had only a fragment of a stem he was not able to make a complete study of the vascular system. To judge from the fragment of the stem which he examined, tin leaves seem to be arranged spirally and the stem i
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