Amphidium mougeotii

   Plants in deep cushions or turfs to 4 cm high, grass green to yellow green or olive green in younger portions, pale brown to brown below. Leaves mostly obscurely 3–4 ranked, not at all secund, moist plants with the erect-spreading keeled along costa, dry plants with proximal portion of leaves erect to imbricated on stem and distal portion coiled and appearing crispate, linear lanceolate to linear, to 3 mm long, about 8–15: 1. Median laminal cells in regular rows, mostly isodiametric, to 12 µm broad, thin walled but with rounded lumens due to strong corner thickenings, with cuticular papillae arranged in 3–5 parallel longitudinal streaks over both the lumens and the lateral cell walls.. Basal cells rectangular to linear, to 12 µm broad, to 8: 1, mostly rather thick walled, mostly with light cuticular papillosity but occasionally smooth. Costa filling less than 1/10 of the leaf base, without a well-defined adaxial groove, ending within a few cells of the leaf apex. Leaf apex acute to narrowly so but without an elongate apical cell. Abaxial cells of costa linear and thick-walled, to 8 µm broad, to 10: 1, smooth. Adaxial cells of costa rectangular, to 15:1, to 10 µm broad, rather thin-walled and smooth. Costa cross-section at mid-leaf with a single layer of guide cells, and with dorsal and ventral bands of substereids. Margin entire or sometimes minutely denticulate near apex.h, recurved especially near top of the differentiated base. Axillary hairs more than 10 celled, 400–500 µm long, with one basal brown cell. Rhizoids red-brown, smooth, to 8 µm in diameter at base, inserted along the adaxial line of leaf insertion, Stem triangular to tetragonal in section, without central strand, with thin-walled inner cortical cells and with 1–2 rows of outer thick walled cortical cells; hyaloderm not present.

   Dioicous. Perichaetia terminal but quickly overtopped by innovations. Perichaetial bracts erect, somewhat smaller but otherwise similar to adjacent vegetative leaves. Seta yellow, to 2 mm long, straight. Capsule erect and symmetrical with the urn elliptical, wide-mouthed, to 1 mm long, about 2: 1, regularly sulcate. Operculum inclined rostrate, to 1/4 of urn length. Annulus not differentiated. Peristome absent. Exothecial cells in regular rows, rectangular, 2–6: 1, mostly 18–22 µm long; cells of the capsule ridges with very thick lateral walls on ridges but those in the valleys of the sulcate capsule having thin walls. Stomates phaneroporous, restricted to neck. Spores smooth, to 15 µm in diameter.

Catalog Notes: Sporophytes would make identifiation certain, but we have not found Amphidium mougeotii in CA with sporophytes.

Vouchers: Del Norte Co.: near Doctor Rock, Siskiyou Wilderness, Six Rivers National Forest, Norris 50287; Fresno Co.: Mist Falls Trail along South Fork Kings River, Kings Canyon National Park, Shevock & York 14492; Plumas Co.: about 2 miles below Cresta Power Station, Norris 52628; Siskiyou Co.: Duck Lake Trail near Parrot's Mill Road, Klamath National Forest, Norris 22866; Tuolumne Co.: Stanislaus River at Board Mill near Sourgrass Campground, Stanislaus National Forest, Norris 77159.

Illustration References: Abramov and Volkova 1998; Ignatov and Ignatova 2003; Ignatov and Lewinsky-Haapasaari 1994; Ireland 1982; Lawton 1971; Smith 1978.

Elevation by latitude plot for Amphidium mougeotii
   in California