Ditrichum heteromallum (Hedw.) E.Britton

  • Authority

    Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part One: Sphagnales to Bryales. Mem. New York Bot. Gard. 69 (1): 1-452.

  • Family

    Ditrichaceae

  • Scientific Name

    Ditrichum heteromallum (Hedw.) E.Britton

  • Description

    Species Description - Plants in yellow-brown, rather glossy tufts 5-15 (rarely 30) mm high. Leaves erect-spreading to weakly secund, not flexuose, scarcely altered when dry, 1.5-3 mm long, subulateacuminate from an ovate-lanceolate base, smooth at back; margins irregularly serrulate at the extreme apex which is very narrow but sometimes blunt; costa filling most of the concave subula and excurrent; upper lamina unistratose (rarely bistratose); cells thick-walled and smooth throughout, linear above (4:1 or more), oblong-linear below. Dioicous. Perigonial buds becoming lateral because of innovation. Perichaetial leaves oblong-sheathing, abruptly subulate, concave. Setae 10-20(-30) mm long, yellowish-orange to red at base, becoming uniformly dark with age; capsules 1.3-2 mm long, erect and symmetric or nearly so, ovoid-cylindric, brown, not or very slightly furrowed when dry and empty; annulus large and revoluble; operculum bluntly conic, 0.4-0.5 mm long; peristome teeth long and slender, fugacious, the major portion occasionally remaining attached to the lid, sometimes unequally unequally bifid, but usually equally split nearly to the basal membrane into 2 filiform, densely and finely papillose, yellowish-to brownish-red forks that m a y be free or coherent and separated only by narrow perforations. Spores (10-) 12-15 µm, yellow, smooth or nearly so.

    Species Description - On soil on ledge of calcareous rock outcrop, 2990 m alt.; Oaxaca (Sierra de Juarez, 46 km N of Ixtlan, Hermann 26192, 26195, 26199, 26202, TENN, MICH).—Mexico; Oregon to British Columbia and Alaska; Europe; (according to the Index Muscorum, South America).

  • Discussion

    Fig. 66

    D. heteromallum (Hedw.) Britt., N. Amer. Fl. 15: 64. 1913. Weissia heteromalla Hedw., Sp. Muse 71. 1801.

    Although phytogeographically unexpected, the Mexican plants agree in every respect with North American and European samples of Ditrichum heteromallum. T h e similar appearance of all four Mexican collections and the closeness of collecting numbers m a y indicate that they all came from a single population or at least grew close together.