Selaginella xanthoneura Valdespino. A median leaf from stem, lower surface B proximal, inner half section of median leaf, lower surface (same leaf shown in A); note elongate and papillate idioblasts (a) C detail of papillae on idioblasts present on inner half section of median leaf, lower surface (same leaf shown in A) D axillary leaf from stem branch, upper surface E proximal half of axillary leaf, upper surface (same leaf shown in D) F distal half of axillary leaf, upper surface (same leaf shown in D). A–F taken from the holotype.