Macromitrium scoparium Mitt.

  • Authority

    Buck, William R. 2003. Guide to the plants of central french Guiana. Part 3. Mosses. Mem. New York Bot. Gard. 76: 1-167.

  • Family

    Orthotrichaceae

  • Scientific Name

    Macromitrium scoparium Mitt.

  • Description

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    Species Description - Plants medium-sized, yellowish green to reddish brown; stems to ca. 10 cm long, branches 0.5-2 cm tall. Leaves spirally crispate when dry, lanceolate, acuminate, 3-6 x 0.4-0.5 mm; margins serrate above, undulate, plane above, recurved below; costa subpercurrent (locally) to short-excurrent; cells in apex elongate, 15-35 x 3-6 µm, in upper median lamina oval to rhomboidal, 15-30 x 8-14 µm, smooth to ± bulging to mammillose-unipapillose, thick-walled, in upper margins rectangular to linear, narrow, forming an incomplete, uniseriate border, often inconspicuous; basal cells long-rectangular, 30-50 x 1-2 µm, thick-walled, porose, mostly tuberculate, rarely smooth. Setae 0.7-2 cm long, smooth; capsules 1.2-2.5 mm long, subglobose, smooth, anisosporous; peristome double, exostome teeth fused into a membrane, papillose; endostome with well developed segments. Calyptrae mitrate, naked.

  • Discussion

    Macromitrium scoparium seems to be a complex of species. The problems are compounded because the syntypes (from Jamaica and Trinidad) are not in the Mitten herbarium. A note by R. S. Williams with a specimen of M. trinitense R. S. Williams indicates that he considered the type of M. scoparium to have an excurrent costa and smooth upper laminal cells. None of our flora specimens has an excurrent costa. Upper laminal cells in local specimens vary from smooth to strikingly mammillose-unipapillose. The basal cells vary from smooth to high-tuberculate. Our material can be sorted, perhaps imperfectly, into two groups. One has smooth to low-tuberculate basal laminal cells, and smooth to only slightly bulging upper lami¬nal cells that are mostly ca. 9-11 pm wide. These plants are most common at the highest elevations in the region, i.e., ca. 700 m. The other, more lowland plants, have high-tuberculate basal laminal cells, and bulging to mammillose-unipapillose upper laminal cells that are mostly 11-14 pm wide. I have found no name whose type matches either of these morphotypes. Therefore, I am using a broadly interpreted M. scoparium for our material. The problem seems unsolvable by a local florula.

  • Distribution

    In non-flooded moist to montane forests, common, 200-700 m, on tree trunks and branches, usually in the canopy.

    French Guiana South America|