150 



THE MARArriALES 



relation of the leaf base and stem apex, especially in connection with the Ophio- 

 glossum-\\]s.e venation in Kaulfussia, is not without significance in its bearing upon 

 a possible relationship between the Marattiaceae and the Ophioglossaceae. 



In all of the genera the lower part of the cotyledon and sometimes the stem 

 apex are more or less covered with hairs and scales. These are less abundant in 

 Marattta and Angiopteris, where they are, for the most part, short hairs whose 

 terminal cells contain a great deal of tannin and stain very strongly. In Kaulfussia, 

 and especially in Dancea, conspicuous scales of peculiar form are abundant. 



A. Section near base of lamina of cotyledon 



B. Part of the lamina, st, stoma. X200. 



C. Young stoma. 



Fig. 129. — Dantea jamaicensis. 



X75. D. An older stoma, X200. 



E. Cross-section of a peltate scale, from young cotyledon. X200. 



In Marattia douglasii the nearly cylindrical petiole is somewhat channeled on its 

 inner side and the single and nearly centrally placed vascular bundle appears almost 

 circular in section. The xylem forms a somewhat crescent-shaped body, completely 

 inclosed by the phloem, but the phloem is less developed upon the inner side and 

 the bundle closely approaches the collateral type. Tannin cells occur, but are not 

 so conspicuous as they are in Angiopteris. The lamina of the cotyledon is similar 

 in structure to that of the latter, the leaves differing mainly in the much smaller 

 development of the mesophyll, which is often reduced to a single layer of cells (fig. 



127, 5). The smaller veins have 

 the xylem reduced to a few — 

 one to three — small tracheids 

 situated upon the upper side of 

 the bundles, so that the bundles 

 are strictly collateral. Stomata 

 of the ordinary form occur upon 

 the lower surface of the leaf and 

 these sometimes show a series 

 of concentrically arranged cells 

 about them. 



The petiole of the cotyledon 

 in //n^/o/j^^r/j resembles in sec- 

 tion that of Marattia, but it is slightly winged (fig. 130), and the tannin cells adja- 

 cent to the vascular bundle are more conspicuous than in Marattia. 



In Kaulfussia (fig. 137, C), where the petiole is stouter than in the other genera, 

 the section is more nearly circular than in Angiopteris, but it is also slightly winged, 

 these wings being developed almost to the proportions of stipules at the contracted 



Fig. 130. 



A. Section of petiole of cotyledon of Angiopteris. X95. 



B. Vascular bundle. X200. The shaded cell is a tannin sac. 



