Isopterygium tenerum (Sw.) Mitt.

  • Authority

    Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part Two: Orthotrichales to Polytrichales. Mem. New York Bot. Gard. 69 (2)

  • Family

    Hypnaceae

  • Scientific Name

    Isopterygium tenerum (Sw.) Mitt.

  • Description

    Species Description - Plants in thin to dense, whitish- to yellow-green mats. Stems 1-2, rarely 3 cm long, 0.5-1.5 mm wide, simple or irregularly branched; cortical cells small and thick-walled; rhizoids smooth, below leaf insertions; pseudoparaphyllia present. Filamentous, multicellular brood bodies sometimes present, simple or branched, often more than 0.5 mm long, green or brown, with cells papillose. Leaves flaccid, closely spaced, erect-spreading and complanate, often secund at the tips, smooth, 0.7-1 mm long, 0.2-0.5 mm wide, ovate to lanceolate, often asymmetric, acuminate; margins plane, serrate to sermlate above the leaf middle, sermlate to entire below, rarely entire throughout; costa none or weak, short, and double; cells smooth, 38-132 µm long, 5-12 µm wide; alar cells short-rectangular to quadrate or transversely elongate in small groups. Autoicous. Setae (3-)5-12(-22) mm long; capsules cernuous or rarely erect, curved or sometimes straight, 0.5-1 mm long, ovoid to ellipsoidal, usually strongly contracted below the mouth when dry; operculum conic-apiculate to obliquely short-rostrate; exostome teeth up to 200 µm long. Spores 9-14 µm in diameter.

  • Discussion

    Fig. 762

    I. tenerum (Sw.) Mitt., J. Linn. Soc, Bot. 12: 499. 1869.

    Hypnum tenerum Sw., Fl. Ind. Occ 3: 1817. 1806.

    H. chrismarii C. Müll., Syn. Muse Frond. 2: 682 1851.

    Isopterygium chrismarii (C. Müll.) Mitt, J. Linn. Soc, Bot. 12: 500. 1869.

    Hypnum cordovenseC. Müll., Linnaea 38: 651. 1874.

    lsopterygiumcordovense(C. Müll.) Jaeg., Ber. Thatigk. St. Gallischen Naturwiss. Ges. 1876-77: 436. 1878.

    I. diminutivum Bartr., J. Wash. Acad. Sci. 18: 581. 1928.

    Isopterygium tenerum is the most common member ofthe genus in Mexico and also the most variable. The plants are usually complanate-foliate with leaves erect-spreading and complanate, ovate-lanceolate, asymmetric, and acuminate and has alar cells in small groups; filamentous, papillose brood bodies are sometimes present on the stems.

  • Distribution

    On rotten logs and stumps or bases oftrees, rarely on rocks and cliff faces at elevations up to 3200 m; Chiapas, Hidalgo, Jalisco, Nayarit, Oaxaca, Puebla, Quintana Roo, San Luis Potosi, Tabasco, Tamaulipas, Veracruz.—Mexico to northern Argentina and Uruguay; throughout the West Indies; widespread in eastern North America, especially along the coast north to Nova Scotia, also in uplands of the Southeast.

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