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Pohlia longibracteata Brotherus in Röll [Mniaceae]
map of distribution

Mniobryum longibracteata (Broth.) Broth. in Engl. & Prantl., Nat. Pfl. 1: 553. 1903.
    Wabera longibracteata (Broth.) Par., Ind. Bryol. ed. 1: 1352. 1897.
    Webera lachenaudii Card. & Ther. in Bailey, Bryologist 7: 66. 1904.

Plants erect in loose reddish-green turfs, to 2 cm high. Leaves approximate imbricate imbricate on the reddish stems, erect and laterally twisted when dry but erect spreading when moist, not concave, linear-lanceolate, to 4 mm long, about 6–10: 1, not plicate. Median laminal cells elongate with transverse walls oblique and with all walls rather thin (lumen: wall ratio 6–12: 1) about 10: 1, smooth, not at all pitted, to 15 µm wide. Leaf lamina unistratose throughout. Basal and alar cells shorter and broader than median cells. Cells near leaf apex somewhat shorter elliptic than median cells, 4–6: 1, with scattered cells distally slightly prorate. Decurrency forming a strip to 3 cells wide distally and descending up to 5 cells down stem. Margin recurved to relaxed throughout, serrulate to serrate in distal 1/2. Limbidium inconspicuous, of 1–3 rows of more narrow cells, mostly rectangular, unistratose throughout. Costa somewhat flattened near the base, filling about 1/8 of leaf base, tapered near the base but evenly wide above, reddish to red-brown, cristate above and ending within a few cells of the broadly acute leaf apex. Costa cross-section round with well defined ad- and abaxial epidermis, with a single layer of guide cells, with a large abaxial band of stereids but with adaxial stereids mostly absent. Axillary hairs 5–6 cells long, to 150 µm, with 2–3 basal brown cells and with thin-walled distal cells which are short and of similar diameter to the basal cells. Rhizoids to 30 µm wide at insertion, densely papillose, brown to red brown, sparingly branched, surrounding an isodiametric macronematal area to 80 µm wide. Stem cross-section pentagonal, mostly strongly winged by the decurrent costae, with a conspicuous reddish central strand, with the hyaline and leptodermous inner corticals gradually transitting to a single layer of only moderately pachydermous, red brown outer cortical cells, without a hyaloderm. Gemmae absent.
    Dioicous with male plants similar to female. Perigonia terminal, bud-like with perigonial leaves larger than vegetative leaves and forming splash-cups. Perichaetial leaves longer and relatively more narrow than vegetative leaves, strongly spreading from the base. Seta pale brown to red-brown, smooth, erect, to 20 mm long. Urn red-brown, to 2 mm long, oblong, 2–3: 1, strongly inclined to pendent, with a poorly defined neck, neither sulcate nor strumose. Operculum conic rostrate to short rostrate. Exothecial cells at capsule mouth not differentiated from median exothecial cells. Exothecial cells at middle of urn isodiametric with rounded lumens and with strongly bulging trigones, to 28 µm broad, in regular rows. Stomates cryptoporous, restricted to neck and immediate base of capsule, not conspicuously raised on pustules, nearly isodiametric. Annulus fragmenting at dehiscence, inconspicuous, of 1–2 rows of relatively thick-walled cells. Exostome pale to yellow-brown, to 450 µm long, inconspicuously shouldered, very inconspicuously horizontally striate at base but strongly papillose distally, dorsal lamellae low. Endostome about as long as exostome, with basal membrane constituting about 1/2 of total length. Segments weakly papillose, keeled and broadly perforated along center line. Cilia 1–3, mostly nodose. Calyptra cucullate and smooth, mostly shed before capsule maturity. Spores to 15 µm, finely papillose to almost smooth.

Pohlia longibracteata is a moss of eroded creek banks and of loose soil of flood plains. It can readily be identified by the erect and unbranched habit; the reddish stems and leaf bases; the very elongate leaves with hand-lens-visible cells. The splash-cup perigonia of the male plants are usually very obvious. When a stem cross-section is viewed under the compound microscope, the pentagonal nature of that cross-section is accentuated by the sharply winged nature of the angles of that pentagon. The species epithet may be somewhat misleading in that all the leaves are, for the genus, unusually long with the perichaetial leaves not as conspicuously longer as the name may imply.

Mail a correction to Paul Wilson ·
LiteratureHolmberg 1969; Jamieson 1969; Kellman 2003; Koch 1950a; Lawton 1971; Shaw 1982; Steere et al. 1954; Thomson and Ketchledge 1958; Yurky 1990, 1995. As Mniobryum longibracteatum Koch and Ikenberry 1954.
IllustrationsMalcolm et al. 2009 p. 189; Lawton 1971; Shaw 1982.
BioregionsCW, NW, SN.
VouchersDel Norte Co.: Damnation Creek, Del Norte Redwood State Park, Norris & Taranto 10972; Humboldt Co.: about 2 miles north of Redwood Valley, Norris 21203 (determined by Shaw); Marin Co.: north of Mt. Tamalpais, Toren 315 (SFSU); Mendocino Co.: Highway 1 near Rockport at milepost 101, Norris 8552 (determined by Shaw); Nevada Co.: Washington Creek, 4.1 miles from Highway 20, Tahoe National Forest, Shevock & Toren 20734 (confirmed by Shaw); Santa Cruz Co.: near Porter Picnic area, 2.8 miles north of Aptos, Forest of Nisene Marks State Park, D. W. Taylor 14662 (UC) and Wilder Creek, Kellman 827 (CAS).

Elevation by latitude plot for Pohlia longibracteata
   in California

Generated: Mon Sep 24 11:57:02 2018