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 Mar atti a, 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. m t 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 

 is probably radial in structure. The general structure of the leaf base seems to be 

 most like that of Kaulfussia. The leaf trace consists of only two vascular strands, 

 which divide up later into several (eight or nine) separate strands, arranged at the 

 base of the leaf in a horseshoe curve, quite like that of Kaulfussia. 1 he arrange- 

 ment of the vascular system of the stipules is probably the same as in the other 

 Marattiaceae. The structure of the stem is also apparently very much like that 

 of Kaulfussia, a section showing only one circle of bundles with a single central 

 strand. The root, which is like that of the other Marattiaceae, has from seven to 

 ten xylem rays. 



