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Ditrichum ambiguum Best [Ditrichaceae]
map of distribution

Plants to 12 mm high, in rather loose, lustreless turfs, olive-green. Leaves mostly inconspicuously tristichous but occasionally markedly so, to 4 mm long, about 10: 1, with a very strongly clasping, almost conduplicate, oblong base which comprises 1/4–1/5 of leaf, gradually contracted to the long, reflexed and channeled subula. Limb irregularly contorted but mostly not laterally rolled. Lamina unistratose at least near margins at base of leaf but multistratose throughout the subula, with cells smooth throughout. Juxtacostal cells of the sheathing base in regular rows, to 12 µm broad, 5–8: 1, rectangular with very thin end-walls and with lateral walls rather thick. Juxtamarginal cells of base markedly more narrow than adjacent internal cells but without alar cells or a well-defined limbidium. Cells of shoulders shorter than more basal cells, mostly about 2–5: 1. Subula with lamina only 1–3 cells wide, with those cells short rectangular, to 7 µm broad, 2–4: 1, arranged in regular rows, rather thick-walled with rounded lumens. Abaxial cells of costa rectangular, to 10 µm wide, to 8: 1; adaxial cells like adjacent laminal cells or somewhat longer. Costa about 1/3 of leaf base, percurrent to excurrent in the long awn. Costa cross-section flat with well-defined single layer of guide cells and strong abaxial and adaxial stereid bands. Margin plane below, becoming erect to somewhat involute above, nearly entire to apex. Rhizoids restricted to extreme base of plant. Stem cross-section rounded triangular, with poorly defined central strand, very thin-walled inner cortical cells, and with only one layer of thicker walled smaller cells in the outer cortex.
    Autoicous with our specimens nearly always with sporophytes. Perichaetial leaves smaller than vegetative leaves but otherwise undifferentiated. Seta to 20 mm, yellow, straight, smooth. Capsule mostly inclined and asymmetrical with the urn cylindric but broadest at base, to 2.2 mm long, about 3–5: 1, not sulcate or strumose. Annulus well-differentiated, not revoluble. Operculum long-conic, to 1/3 of urn length. Peristome reddish-brown, mostly 300–500 µm long but occasionally less than 200 µm, densely spiculose papillose, bifid nearly to base, or occasionally only perforate to base. Exothecial cells irregular in size and shape, rectangular with oblique end-walls, not in regular rows, to 15 µm wide, 1.5–4: 1, rather thin-walled. Stomata few, restricted to neck. Spores spherical, to 16 µm, lightly papillose.

Mail a correction to Paul Wilson ·
LiteratureBourell 1981; Crum and Anderson 1981; Holmberg 1969; Jamieson 1969; Kellman 2003; Koch 1950a, 1951e; Lawton 1971; Shevock and Toren 2001; Spjut 1971; Toren 1977; Yurky 1990, 1995.
IllustrationsMalcolm et al. 2009 p. 91; Crum and Anderson 1981; Lawton 1971.
BioregionsCaR, CW, NW, SN.
VouchersGlenn Co.: about 0.5 mile north of Lone Star Camp, Norris 47970; Humboldt Co.: Coyote Peak on Bald Hills Road, Norris 22341; Lake Co.: Forest Road 18N34, about 1 mile east of The Slides west of Lake Pillsbury, Mendocino National Forest, Toren & Bourell 5047 (CAS); Mendocino Co.: Ornbaun Creek near Mountain View Road, Norris 53183; Santa Cruz Co.: Ice Cream Grade, 1.6 miles west of junction with Empire Grade, Whittemore 4439 (MO); Sonoma Co.: Gualala River near Soda Spring, Norris 86983; Trinity Co.: Rattlesnake Creek at Hell Gate Campground east of Forest Glen, Norris 23817; Tulare Co.: Clover Creek off of General's Highway, Marble Fork Kaweah River, Sequoia National Park, Shevock 15631 (determined by Toren).

Elevation by latitude plot for Ditrichum ambiguum
   in California

Generated: Thu Jul 19 04:28:57 2018