Orthotrichum flowersii

   Plants to 0.5 cm high, erect in low green to somewhat castaneous tufts or cushions. Leaves to 2.5 mm long, erect spreading when moist but loosely appressed when dry, oblong-ovate to broadly ovate, 2.5–3: 1, broadest immediately above the base. Leaf apices rounded to obtuse, often with a minute apiculus. Median laminal cells isodiametric with rounded lumens, thin-walled with small corner thickenings, to 18 µm wide, with 1–2 very low and unbranched, often inconspicuous papillae on each surface. Basal marginal cells smooth, somewhat smaller than the median cells, mostly quadrate. Basal juxtacostal cells smooth, short rectangular, 1.5–3: 1, with lateral walls thin and straight. Margins entire to crenulate, recurved except at immediate base and apex. Costa ending more than ten cells from apex, lying in a very sharply defined abaxial keel. Costa cross-section rounded triangular, essentially homogeneous or with abaxial cells reduced, 2–3 cells thick, with 3–5 cells along the abaxial perimeter and only 2 cells on the adaxial surface. Axillary hairs not offset from leaf insertion. Laterally inserted axillary hairs to 5 cells and 125 µm long with one lightly colored basal brown cell; central axillary hairs mostly about twice as long. Rhizoids usually abundant near base of plant, smooth and moderately thin-walled, pale to light brown, to 20 µm in diameter at base, sparingly branched. Stem cross-section rounded pentagonal, with no central strand, with leptodermous and hyaline inner corticals and with very little development of an outer stereome. Gemmae brownish, inserted on adaxial lamina, uniseriate, 6–8 cells long.

   Autoicous with perigonia in leaf axils near the perichaetia or on the apices of separate short branches. Perichaetia terminal with bracts somewhat smaller than vegetative leaves. Capsule immersed to emergent on a yellow to yellow brown, smooth and erect seta to 0.5 mm in length. Urn orange-brown, to 1.2 mm long, 2–2.5: 1, erect, sulcate with eight ribs in distal 3/4, lightly to strongly strangulate. Operculum conic-apiculate. Annulus well-defined, revoluble. Exothecial cells in cross-section bistratose with only the outer walls of the outer layer thickened. Exothecial cells at capsule mouth differentiated in up to 4 rows, mostly not reddened, to 15 µm wide, transversely elongate, 1/2–1/3: 1, with rounded lumens. Exothecial cells at middle of urn short rectangular, 1.5–2.5: 1, to 20 µm broad, very thick walled on ridges of capsule with lumen: wall ratio 0.25–1: 1, thinner walled in valleys of the sulcate capsule. Stomata mostly near middle of urn, cryptoporous, only partially obscured by subsidiary cells. Exostome teeth 8, reflexed, pale, to 200 µm long, densely papillose below but striate-papillose above. Endostome segments 8, almost as long as exostome, smooth to very lightly papillose, arising from only one row of cells. Calyptra glabrous and very lightly plicate, oblong-campanulate. Spores green, to 16 µm, finely papillose.

Vouchers: Kern Co.: Black Gulch near Lake Isabella, Sequoia National Forest, Norris & Piippo 82204; Los Angeles Co.: Black Jack Campground at base or Orizaba Mountain, Santa Catalina Island, Shevock & Thorne 4073; Riverside Co.: USFS Guard Station, San Jacinto Mountains, San Bernardino National Forest, Harpel 994 (pers. herb.); San Bernardino Co.: Paris Hill City Park, City of San Bernardino, Harpel 658 (pers. herb.); San Diego Co.: Highway 94 at junction to Outdoor World Campground about 3 miles east of La Pasta Road, Norris 77797; Tulare Co.: South Creek just above South Creek Falls off of County Road M-99 north of Kernville, Sequoia National Forest, Norris 87078 and South Fork Kaweah River near Clough Cave, Sequoia National Park, Norris & Shevock 92730.

Literature: Galloway 1978; Harpel 1980a; Harthill et al. 1979.

Illustration References: Vitt 1971, 1973.

No illustrations found in database.

Elevation by latitude plot for Orthotrichum flowersii
   in California