Portal de Periódicos da CAPES

Studies in North American Bryaceae I-II

1967; American Bryological and Lichenological Society; Volume: 70; Issue: 1 Linguagem: Inglês

10.1639/0007-2745(1967)70[106

1938-4378

Howard Crum,

Botany and Plant Ecology Studies

sandbergii Holz., of western North America, should be segregated as a monotypic genus Roellia Kindb. A detailed description and a distributional summary are given with the new combination Roellia roellii (Broth. ex Rbill) Andrews ex Crum. Pohlia tozeri (Grev.) Delogne is transferred to Epipterygium and both genus and species are described in detail. I. THE GENUS ROELLIA KINDB. sandbergii Holz., as it is called in Grout's Moss Flora of North America, is a splendid moss, recognizable with the unaided eye and presenting no problems in identification, but its relationships require some elucidation. Known only from western North America, this species bears some passing resemblance to Mnium, perhaps because of its broad leaves and pale-, often vivid-green coloration, but it is much more obviously similar to or Rhodobryum both in appearance and in structure. Surprisingly Kabiersch (1937) considered it a member of the Mniaceae, as Brotherus (1924) had also done previously. The long, narrow capsules tapered to a well developed neck are typical of Bryum, as are the superficial stomata, distinctly revoluble annulus, and pale, delicate endostome. Furthermore, the paraphyses associated with the antheridia are few, pale, and filiform, as in Bryum; the leaf margins are indistinctly bordered by narrow but not greatly differentiated cells; the marginal serrations are caused by mere projections of cell ends; and the lower leaf margins are somewhat reflexed. The elongate-hexagonal leaf cells, though larger and more delicate than those of any other member of the Bryaceae, with the possible exception of some species of Epipterygium, are utterly unlike anything in the Mniaceae. Some superficial resemblance to Rhodobryum is provided by the arrangement of leaves in rosulate tufts, a feature shared by many species of Bryum, but the plants do not grow upright from horizontal, underground stems, and the leaf structure is quite unlike that of a Rhodobryum. Andrews, in Grout's Moss Flora of North America, included this species, with much logic, in Bryum. As a rule, I share his well known aversion to the subdivision of genera. I feel that a genus should be conveniently recognizable, if at all possible, and should be a natural entity consisting only of species of an obviously common origin. Small, segregate genera often serve no useful purpose and obfuscate the evidence of phylogeny. In the case of this species, however, a combination of rather striking characteristics justifies segregating the genus Roellia from the relative uniformity of Bryum: the broad, flaccid, shiny leaves with broad points, as well as their arrangement in rosulate tufts, and particularly the very large, delicate, elongate leaf cells with squared-off rather than pointed ends. (In the Bryaceae, generic differences are, for the most part, poorly marked, and it is satisfying to observe that the characters which make this species so remarkably distinctive as a Bryum are far greater and more obvious than those separating from Pohlia, for example.) 1 Herbarium, University of Michigan, Ann Arbor, Michigan. This content downloaded from 157.55.39.162 on Thu, 11 Aug 2016 05:53:49 UTC All use subject to http://about.jstor.org/terms 19671 CRUM: NORTH AMERICAN BRYACEAE 107 Regardless of the generic disposition, some nomenclatural problems must be faced. The name Roellia, as originally proposed by Kindberg in 1896, may be considered invalid, because it was applied to both generic and subgeneric categories, although it is fairly certain that Kindberg intended it only as a subgeneric designation, if one may judge from the fact that he prefaced his brief comments with Mnium (Roellia) simplex as a new combination. In the following year (1897), he clearly designated Roellia as a genus and also made the combination Roellia simplex; this I would consider valid publication, and I see no reason to refer to the previous provisional publication of the name in any parenthetical way. It is remarkable that such a common, widely distributed, and distinctive moss should not have been described until 1890 and also that four different names were provided for it between 1890 and 1895. The oldest name, Mnium roellii Broth. ex Roll (1890), cannot be used in because of roellii Philib., which was published earlier in the same year. lucidum Britt. (1891) is antedated by B. lucidum James ex Durand (1856), and B. simplex Kindb. ex Mac. & Kindb. (1892) is invalidated by B. simplex L. ex Richter (1840). Andrews (1940) rightly chose the name sandbergii Holz. (1895). In Roellia, the oldest name for the species, Mnium roellii Broth. ex Rall (1891), is available for recombination. Andrews actually published the combination Roellia roellii, but as he did not accept the segregate genus himself, his provisional combination has no legal standing. I supply the same combination here to satisfy Article 34 of the International Code. Roellia Kindb., Gen. Eur. & North Amer. Bryin. 37. 1897. Roellia Kindb., Rev. Bryol. 23: 22. 1896, nom. inval. (used provisionally as a genus or as a subgenus of Mnium). Roellia roellii (Broth, ex Roll) Andrews ex Crum, comb. nov. Roellia roellii (Broth. ex Roll) Andrews in Grout, Moss Fl. North Amer. 2: 240. 1940, nom. inval. (mentioned provisionally and not accepted by the author). Mnium roellii Broth. ex Rill, Bot. Centralbl. 44: 420. 1890. (Non roelli Phil., 1890.) lucidum Britt., Bull. Torrey Bot. Club 18: 53. 1891. (Non James ex Durand, 1856.) simplex Kindb. ex Mac. & Kindb., Cat. Canad. P1. 6: 135. 1892. (Non L. ex Richter, 1840.) Mnium lucidum (Britt.) Broth., Hedwigia 32: 293. 1893. sandbergii Holz., Contrib. U.S. Natl. Herb. 3: 271. 1895. Mnium simplex (Kindb. ex Mac. & Kindb.) Kindb., Rev. Bryol. 23: 22. 1896. Roellia lucida (Britt.) Kindb., Sp. Eur. & North Amer. Bryin. 2: 345. 1897. Roellia simplex (Kindb. ex Mac. & Kindb.) Kindb., Sp. Eur. & North Amer. Bryin. 2: 346. 1897. Plants in loose, shiny, brightor pale-green tufts about 1.5-3 cm high. Stems wiry and erect-flexuose, simple, red, angled, somewhat radiculose toward the base, nearly naked below, rosulate-foliate at the tips. Leaves small and scalelike below, abruptly larger and crowded at the stem tips, spreading when moist, 3-6 mm long, broadly oblong or obovate, broadly acute and sometimes shortly cuspidate-acuminate, somewhat decurrent; margins serrulate in the upper half or somewhat more, -reflexed in the lower half, especially when dry; costa relatively slender, ending just below the apex, yellowish, brown; upper cells pale, lax and thin-walled, large, oblong-hexagonal, mostly about 3:1, 30-37 X 90-100/i, narrowly rhomboidal in 2 marginal rows forming a fairly distinct border (more conspicuous when dry); lower cells more nearly rectangular. Dioicous; paraphyses of perigonia few, pale, filiform. Setae single, stout, 30-50 mm long, flexuose, orange-yellow, becoming reddish below; capsules horizontal to This content downloaded from 157.55.39.162 on Thu, 11 Aug 2016 05:53:49 UTC All use subject to http://about.jstor.org/terms 108 THE BRYOLOGIST [Volume 70 pendent, long-cylindric, 5-7 mm long (including the tapered and inconspicuous neck which is about 1.5-2 mm long), lightor yellow-brown; annulus large and revoluble; convex-conic, bluntly acute or mammillate; stomata superficial, in the neck; exostome teeth yellow, lance-acuminate, densely and minutely papillose below, more coarsely papillose at the tips, very narrowly bordered, trabeculate at back; endostome hyaline or faintly yellowish, finely papillose, with a high basal membrane, keeled and perforate to gaping segments, and long, slender, somewhat nodulose cilia in groups of 2-4. Spores spherical, 11-13,i, finely roughened or nearly smooth. Calyptrae pale brown, cucullate, smooth, naked. Distribution: On humus and soil in shady places in coniferous forests in the Pacific Northwest, from British Columbia to northern California and inland to Alberta, Montana, and Wyoming. (I have seen specimens from British Columbia, Alberta, Washington, Oregon, California, Idaho, Montana, and Wyoming.) The following collections, none specified as the type, were cited after the original description: Cascaden: Mount Hood (Oregon) ad rivulum glacialem, 7000 ped alt. c. fr. (1082); Easton (Washington) c. fr. (648), Weston c. fr. (486), Rigi ad Clealum Lake c. fr. (914), Kahchess Lake c. fr. (818). Illustrations: Britton, Bull. Torrey Bot. Club 18: P1. 114, Fig. 1-10. Brotherus in Engler & Prantl, Die natiirl. Pflanzenfam., ed. 2. 10: Fig. 859. Grout, Moss Fl. North Amer. 2: P1. 97A. Kabiersch, Hedwigia 76: 8, Fig. 1. Exsiccati: Grout, North Amer. Musci Perf. 437 (as sandbergii). Holzinger, Musci Acro. Bor.-Amer. 296 (as Roellia lucida). Macoun, Canad. Musci 631 (as simplex). Verdoorn, Musci Sel. et Crit. 236 (as Roellia lucida).