A Study of Groutiella apiculata and G. mucronifolia

Abstract

Variation in stem height, basal border length, and apex morphology are so great that the populations usually referred to the two species Groutiella apiculata and G. mucronifolia seem instead to be conspecific. The correct name for the widely distributed species is G. mucronifolia, while G. apiculata must be applied to a little-known Mexican species. Groutiella Crum & Steere is a genus of tropical and subtropical mosses related to Macromitrium Brid., but distinguished from that genus by its leaves having basal cells and bounded at the base by a border of elongated cells. Groutiella apiculata (Hook.) Crum & Steere and G. mucronifolia (Hook. & Grev.) Crum & Steere have been recognized as distinct species, both of which occur throughout much of tropical and subtropical America from Florida to southern Brazil. They are easily distinguished from other American species of Groutiella by characters of secondary stem leaves. Grout (1946), using the generic name Craspedophyllum Grout, gave the most complete summary of the characters used to separate G. apiculata and G. mucronifolia. The height of the secondary stems of G. apiculata is said to be greater than 1 cm, while in G. mucronifolia it is less than 5 mm. The length of the basal border of elongated cells is one-half or more the length of the leaf in G. apiculata; in G. mucronifolia the basal border is one-third or less the length of the leaf. The apex of the leaf in G. apiculata is characterized as apiculate by the excurrent costa (rarely a few leaves merely acute). The apex of G. mucronifolia is short-apiculate. In the key the species are separated, in part, on the shape of the apex: Mucro prominent versus Mucro very short in G. apiculata and G. mucronifolia respectively. The differences between these species are graphically summarized in Fig. 1. This figure is based on a composite of descriptions found in Grout (1946) and subsequent treatments (Bartram, 1949; Crum & Bartram, 1958; Crum & Steere, 1957; Florschiitz, 1964). One would expect to be able to separate these species with some ease, but this does not happen. I have encountered difficulty with collections from Jamaica, Puerto Rico, and Trinidad and from various parts of Central America. Florschiitz (1964) suspected that these species would prove to be one variable taxon after further study. Are stem height, border length, and apex morphology of value in characterizing two distinct morphological entities, Groutiella apiculata and G. mucronifolia? The 1 Department of Botany, Duke University, Durham, North Carolina 27706. Present address: Cryptogamic Herbarium, Missouri Botanical Garden, 2315 Tower Grove Avenue, St. Louis, Missouri 63110. This content downloaded from 207.46.13.101 on Sat, 08 Oct 2016 05:57:27 UTC All use subject to http://about.jstor.org/terms 608 THE BRYOLOGIST [Volume 73 stems I-3 cm tall '2 tm pt y * ~'fstems up to 0.5 cm tall Border I/2 length of leaf Border I/3 length of leaf Apex obtuse, Apex obtuse to retuse, with strong apiculus with small mucro FIGURE 1. A summary of the differences which are supposed to exist between Groutiella apiculata (left) and G. mucronifolia (right). purpose of this study is to answer this question. The study is specifically limited in scope to a consideration of these three gametophytic characters.