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Quantitative Taxonomic Study of Morphology in Epipterygium

1984; American Bryological and Lichenological Society; Volume: 87; Issue: 2 Linguagem: Inglês

10.2307/3243119

1938-4378

Jonathan Shaw,

Plant Taxonomy and Phylogenetics

Epipterygium, a small genus of the Bryaceae, is represented by four American species, which occur north of Colombia. Leaves in Epipterygium are arranged in a 2/5 phyllotaxy, and the degree of leaf dimorphism varies both within and between species. Epipterygium tozeri and E. wrightii are rather distinct, but E. mexicanum and E. immarginatum of Mexico and Central America intergrade morphologically. Analysis of variance of each of 18 morphological characters shows that the two species differ significantly in leaf cell width, length to width ratio, and border development. Epipterygium mexicanum is the correct name for plants formerly known as E. im- marginatum. Descriptions and illustrations are provided for the four Epipterygium species of North and Central America and the West Indies. Epipterygium is a small genus of the Bryaceae consisting of about ten species. It is represented in warm, humid regions of tropical America, Africa and Asia but is absent from Australia and New Zealand. Epipterygium tozeri is distributed in west- ern North America, Great Britain, southern Europe and westward along the Mediterranean, and Japan. The only other temperate species, E. rigidum, was described from the Caucasas Mountains. In tropical America, three species occur: E. mexicanum, E. immarginatum, and E. wrightii. The genus takes its name in reference to the com- planate shoots with dimorphous leaves character- istic of some species. While independently studying tropical American material of species characterized by extremely complanate-dimorphous foliation, Lindberg (1862) and Mitten (1863) proposed the new (now synonymous) generic names Epiptery- gium and Anisostichium, respectively. As the names siuggest, both authors considered the unusual phyl- lotaxy to provide the chief diagnostic features. In the most commonly known species, E. tozeri, how- ever, shoots are often scarcely if at all complanate, and are essentially uniformly foliate; in other species the degree of leaf dimorphism varies from popu- lation to population. Among tropical American species, only E. wrightii of the West Indies has leaves consistently and strongly dimorphous, with dorsal leaves smaller and narrower than lateral leaves.