Amblystegium humile (P.Beauv.) Crundw.

  • Authority

    Hedenäs, Lars. 2003. Amblystegiaceae. Fl. Neotrop. Monogr. 89: 1--107. (Published by NYBG Press)

  • Family

    Amblystegiaceae

  • Scientific Name

    Amblystegium humile (P.Beauv.) Crundw.

  • Type

    Type. U.S.A. Pennsylvania s.n. (isotype, S; apparently separated from the Arnott material in GL; cf. Crundwell, 1981).

  • Synonyms

    Amblystegium megachaete Dusén, Hypnum humile Harv., Leptodictyum humile (P.Beauv.) Ochyra

  • Description

    Species Description - Plants small or medium-sized; green or yellow green. Stem pinnately or irregularly pinnately branched in one plane; central strand present or not, slender; pseudoparaphyllia triangular or broadly triangular; paraphyllia rare, narrow-lanceolate; axillary hairs with 1-2-celled upper part, this hyaline when young. Stem leaves 0.9-1.5 mm long, erect-patent to spreading, straight or slightly homomallous, ovate or ovate-triangular, narrowing abruptly or occasionally gradually to apex, strongly constricted at insertion, slightly concave, not or very short-decurrent; apex acuminate; margin in upper part sometimes obtusely denticulate, below entire or almost so; costa single, ending 50-65% of way up leaf, 31.0-63.0 µm wide at base; median laminal cells (26.0-)31.5-65.0 × 8.0-13.5(-15.5) µm, thin-walled or slightly incrassate, eporose; alar cells not differentiated from other basal cells. Inner perichaetial leaves narrowing abruptly to acuminate apex, plicate. Seta 14-23 mm long, smooth; capsule curved, horizontal; operculum conical. Exostome outside cross-striolate in lower part; border widened at middle of teeth. Endostome cilia as long as segments or almost so. Spores 12.0-15.5(-l6.5) µm, finely papillose.

  • Discussion

    Amblystegium humile has been reported from Mexico (e.g., Delgadillo et al., 1995; Sharp et al., 1994),but I have not seen any correctly identified material from this area. The figure in Sharp et al. (1994) cannot unambiguously be referred to this species, but could just as well illustrate a plant of A. varium. Amblystegium humile is characterized by stem leaves that are relatively strongly constricted at the insertion, a costa that ends slightly above midleaf, and undifferentiated alar cells. The differences between A humile and A. varium are discussed after the latter.

    Crum & Anderson (1981: p. 937), Nyholm (1965: p. 490; as Amblystegium kochii).

  • Distribution

    Guatemala (altitude unknown) and Haiti (610 m a.s.l.). Widespread mainly in temperate N America and Eurasia; also on Madeira. Within the neotropical area recorded from a wet log; otherwise growing in various wet or moist habitats.

    Guatemala Central America| Chimaltenango Guatemala Central America| Haiti South America|