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Orthotrichum spjutii Norris & Vitt [Orthotrichaceae]
map of distribution

Plants in compact tufts or cushions, to 7 mm high, sordid green to red brown often with a glaucous cast. Leaves to 2 mm long, about 3: 1. erect-spreading to spreading when moist but strongly appressed when dry, ovate below but contracted at about 2/3 to a lance-ligulate distal portion. Leaf apices bluntly acute to obtuse. Median laminal cells to 12 µm wide, not regularly arranged in rows, isodiametric to slightly elongate along an oblique axis. Lumens of the median cells rounded due to the strong corner thickenings. Papillae several over the lumens on both surfaces, high and repeatedly branched. Basal marginal cells to 14 µm wide, isodiametric to short rectangular, pellucid and smooth, not clustered in a defined auricle. Basal juxtacostal cells smooth, rectangular to linear, to 12 µm wide, 4–12: 1, pitted or sinuose-thickened on lateral walls, reddish-brown or concolorous. Cells on adaxial surface of costa short-rectangular, 1.5–3: 1. Margins markedly papillose crenate, recurved from base to apex. Costa ending within a few cells of apex, lying in a sharply defined keel. Costa cross-section at mid-leaf nearly homogeneous, elliptical, 1.2–1.5: 1. Costa 4 cells thick, and with 7–8 cells along the abaxial perimeter. Median axillary hairs with one or two basal brown cells, not offset from leaf insertion, to 8 cells and 250 µm long with the laterally inserted ones much shorter than the lateral ones. Rhizoids very sparsely produced at base of plant, to 20 µm in diameter at insertion, smooth, red-brown, sparingly branched. Stem cross-section irregularly pentastichous, without a central strand, nearly homogeneous but with 1–2 layers of somewhat more pachydermous, red-brown outer cortical cells.
    Autoicous with perigonia in leaf axils near the perichaetia. Perichaetial bracts not differentiated from vegetative leaves. Capsule emergent, often rather shortly so, on a pale-brown, smooth and erect seta which seldom exceeds 2.5 mm in length. Urn pale-brown to stramineous, 1.5–2 mm long, 1.5–2: 1, erect, sulcate with eight ribs, especially in distal 1/2, often strongly strangulate. Operculum conic-apiculate to short rostrate. Annulus falling in fragments. Exothecial cells in cross-section single-layered. Exothecial cells at capsule mouth in up to 6 rows. mostly concolorous with median exothecial cells, to 25 µm wide, quadrate to transversely elongate with rounded lumens and thick walls. Exothecial cells at middle of urn differentiated into ridge and valley cells in vertical rows. Ridge cells rather thick walled with lumen: wall ratio 2–4: 1, rectangular, 3–6: 1, to 15 µm broad. Exothecial valley cells thin-walled and regularly rectangular, to 30 µm wide, 2–4: 1 capsule. Stomata phaneroporous, mainly in middle of urn. Peristome absent. Calyptra ovoid-campanulate, prorate on surface cells of flare, rather densely covered throughout with papillose hairs. Spores green, 10–12 µm, finely papillose.

This plant is immediately distinctive because of the gymnostomous feature. I have opened numerous operculate capsules, and have even examined the inside surface of the operculum. Frequently a diaphanous low membrane is present at the capsule mouth, and this membrane may have a hint of division into exostome teeth. However, a true peristome seems not to be developed.
    The gametophyte of this species is especially distinctive because of its strongly recurved to revolute leaf margins which extend to the leaf apex rendering the abaxial apex almost cucullate. The rather strong distinction of the broad leaf base from the lance-ligulate apex is a further point of distinction. The extremely small size of the spores is anomalous among North American members of the genus.
    In the field, one might identify this plant to Orthotrichum pylaisii Brid., but the glaucous coloration and the strangulate capsules might alternatively suggest cryptoporous species such as Orthotrichum pallens Bruch. ex Brid. or Orthotrichum alpestre Hornsch. ex B.S.G.

Mail a correction to Paul Wilson ·
LiteratureNorris and Vitt 1993.
IllustrationsMalcolm et al. 2009 p. 213; Norris and Vitt 1993.
BioregionsSN, SNE.
VouchersMono Co.: near outlet of Koenig Lake, east of Sonora Pass, Toiyabe National Forest, Norris 57207 & 57210; Tulare Co.: between BLM Long Valley Campground and South Fork Kern River, Domeland Wilderness,Sequoia National Forest, Shevock 15154, 15158, & 15161.

Elevation by latitude plot for Orthotrichum spjutii
   in California

Generated: Fri Aug 17 08:31:20 2018