Archidium alternifolium

   Plants with stems to 6 mm high in dense turfs or scattered, yellow-green to olive-green. Leaves on lower portion of plants scale-like, rather abruptly changing to the large perichaetial and subperichaetial leaves, not falcate, to 2 mm long, narrowly ovate-lanceolate to lanceolate without a distinction between the base and the limb. Median cells of leaf rectangular with oblique end-walls, smooth, to 12 µm broad, 4–6: 1, in regular rows. Cells of base to 10 µm broad, shorter than median laminal cells and often quadrate across the base. Cell walls mostly rather thin with lumen: wall ratio seldom less than 8: 1. Costa occupying about 1/8 of leaf base, gradually tapering and percurrent to short-excurrent in the acute apex. Costa cross-section at mid-leaf with moderately well-defined epidermises and with central cell substereidal in 3–4 layers. Leaf uniformly unistratose with margins plane, serrulate above or serrulate almost to the base. Axillary hairs to 125 µm, 4-celled, with basal cell hyaline but of reduced diameter compared with the more distal cells. Stem without a central strand and with inner cortical cells large and thin walled but with small but rather thin-walled outer cortical cells and with outermost layer collapsed in older stems and appearing as a hyaloderm.

   Autoicous with antheridia naked and axillary below the perichaetia. Perichaetial leaves only gradually larger than the immediately adjacent subperichaetial leaves. Perichaetia terminal, forming a capitate cluster, mostly with several innovations even during early stages of capsule growth. Seta almost non-existent, straight. Capsule globose and cleistocarpous with the exothecial cells hexagonal and rather thin-walled, yellow brown to stramineous when mature, to 0.6 mm long, symmetric. Calyptra not developed or appearing only as a crater surrounding base of sporophyte much in the manner of many leafy hepatics. Operculum absent with capsule cleistocarpous. Stomata absent. Spores mostly only 16 per capsule, mostly more than 150 µm, smooth to faintly papillose, swelling capsule in later growth causing numerous nodular bulges in capsule surface.

Vouchers: Santa Cruz Co.: Headwaters of Pleasley Gulch near Wilder Ridge Loop Trail, Wilder Ranch State Park, Kellman 2249 (CAS) [confirmed by Spence].

Literature: Kellman 2003. The historic California collections cited in the bryological literature as Archidium alternifolium we have determined to represent Pleuridium subulatum. This species, however, was recently confirmed for the state.

Illustration References: Malcolm et al. 2009 p. 82; Grout 1928-40; Ignatov and Ignatova 2003; Snider 1975.

No illustrations found in database.

Elevation by latitude plot for Archidium alternifolium
   in California