On the Cuticular Structure of the Devonian Plant Psilophyton.

Abstract

Summary An investigation of the cuticle of Psilophyton princeps Dawson from the original locality in Canada has revealed the presence of stomata on the epidermis of the stem. This epidermis resembles in a general wily that of the petrified members of the Psilophytales from the Rhynie Chert, but the stomata differ in the presence of cuticular thickenings and the epidermal cells are usually papillate and not ridged. In the numerical distribution of stomata on the stem, Psilophyton agrees with Asteroxylon rather than Rhynia. There is no evidence that the highly cuticularised spines are homologous with the traumatic intumescences of Rhynia, and they differ from the slightly larger and less spine-like leaves of Asteroxylon, with which a closer comparison is possible, in the absence of stomata.