Studies on Hepaticae LXI. Trichocoleaceae
Schuster, R. M.
Trichocolea and Leiomitra (Trichocoleoideae) are shown to be distinct in both form of gynoecia (Trichocolea lacks a calyptra and perianth; Leiomitra has a bulbous or caplike calyptra and a ± distinct – if rudimentary – perianth) and sporophytes (Trichocolea has an ellipsoidal capsule; Leiomitra a ± spherical one). The two genera are similar in many respects to Temnoma (Temnomoideae), as in the form of leaf cells, cuticle, dissection of leaves and underleaves, and form of the cilia of leaf lobes and margins; in both subfamilies the polystratose capsule wall has a hyaline epidermal layer. Leiomitra in some respects is intermediate between Trichocolea and Temnoma. Although the Trichocoleaceae s. lat. almost uniformly have gynoecia terminal on leading, elongated leafy axes, a single species, L. mastigophoroides Schust. is discussed in which gynoecia are relegated to short, specialized lateral branches, thus mimicking the genus Mastigophora. Finally, the isolated monotypic genus Eotrichocolea is described; it is unique in the rather erect growth and tapered, distally microphyllous branches. These last two taxa are the only ones in Trichocoleoideae in which branching from ventral merophytes is retained, at least sporadically so. The classification of Trichocoleoideae has been largely derived from study of sterile material. It has become clear that position of gynoecia, the degree of preservation – or loss – of a perianth, the degree to which a coelocaule is elaborated and the form of the capsule all represent important taxonomic criteria. Reliance on criteria of the sterile gametophyte has strongly limited advances in our understanding of the group. Capsule-wall microanatomy is evidently of very limited taxonomic significance in the subfamily.