Studies on the fern genera Bolbitis and Egenolfia. I. Morphology of the sporophytes

Abstract

The rhizome of 12 species of Bolbitis and 7 species of Egenolfia studied is creeping, more or less flattened dorsiventrally, often tenaciously attached to the substratum by wiry roots, and brittle. Basally attached, auricled paleae, bearing terminal and marginal glandular hairs clothe the rhizome. The ground tissue of the rhizome is parenchymatous: slender sclerenchyma strands are scattered in the ground tissue (except in B. presliana and E. helferiana). The vascular cylinder is solenostelic with a broad, intact, often gutter-shaped, root-bearing, ventral region, and the dorsal region highly dissected by 2 (3 or 4 in some spp.) longitudinal rows of large leaf gaps. The leaf traces are multiple strands: associated with each leaf trace is a solitary branch trace, generally bearing one root trace and originating either independently from the abaxial end of the leaf gap or along with the abaxial bundle of the leaf trace. In some species, either the branch- or the root-trace, or both, is vestigial. Leaves are restricted to the dorsal surface of the rhizome and are usually in 2 but may be in as many as 4 rows. They are once-pinnate, and dimorphic. The stipe and rachis possess a pair of longitudinal grooves on the adaxial surface. Many vascular bundles ascend the rachis: the 2 adaxial bundles are larger than the others. In the rachis the adaxial ones fuse together to form a median dorsal bundle and the others fuse together to form a median ventral bundle: toward the apex of the leaf both merge together. The pinna traces are paired strands originating from the adaxial bundle and the bundle next to it. Venation is free in Egenolfia (except the tendency for areole formation in E. bipinnatifida), and goniopteroid with variation according to species in Bolbitis. The terminal pinna is prolonged in many species. A sub-apieal vegetative bud is found laterally on the dorsal surface of the midrib on the terminal pinna; in some species similar buds are borne also on the lateral pinnae. The fertile leaves are seasonal and lamina of the fertile pinnae is highly reduced. Sporangia are acrostichoid in distribution, and uniseriate hairs occur, mixed with them. The sporangial stalk is 3 cells thick near the capsule, the 3rd row being short and formed secondarily as a protrusion from the proximal end of the capsule wall, below the stomium.