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|Andreaea nivalis W. J. Hooker [Andreaeaceae]|
Mail a correction to Paul Wilson
Trans. Linn. Soc. London 10: 395. 1811.
Andreaea macounii Kindb. in Mac., Bull. Torrey Bat. Club 17: 83. 1890. Andreaea baileyi Holz., Bryologist 27: 78. 1924.
Plants in dense wefts or tufts, to 50 mm high, almost unbranched, greenish-brown in younger portions but red-brown in older portions. Stems red-brown, very brittle, distally hamate. Leaves, when dry, proximally arching outward from the stem but stiffly erect distally; leaves when moist little changed. Leaves to 1.5 mm long, about 3.5–5: 1, lanceolate and falcate, acuminate apex, concave below. Median cells prorate-papillose throughout, arranged in regular rows, to 8 µm wide, quadrate to transversely elongate, 1–1.5: 1, with angular lumens and with no corner thickening, incrassate with lumen/wall ratio about 2–4: 1. Marginal cells of leaf similar but somewhat more transversely elongate that the interior ones. Basal marginal cells of leaf not different from median cells; interior basal cells similar in width but rectangular without pitting of lateral walls, 4–6: 1. Costa percurrent or very shortly excurrent in a narrow subula, round in cross-section in subula but flattened and less conspicuous near base. Cells of abaxial surface of costa papillose, narrowly linear with lumens often almost obscured by wall-thickening; cells of adaxial surface of costa linear and thick-walled, not papillose. Margins ascending and crenulate or crenulate-papillose throughout, not at all decurrent. Stem rounded pentagonal, with a red-brown stereome of 2–3 cell layers, with internal cells hyaline, enlarged and thin walled, without a central strand. Axillary hairs to 25 µm long, 2-celled, not offset, one isodiametric and pale brown, the other elongate and clavate, very thick-walled with lumen wall ratio about 1: 1. Gemmae not seen.
Plant dioicous with male and female plants similar and usually intermixed. Perichaetial leaves similar in shape to vegetative leaves but somewhat larger, to 2 mm long, spreading and not sheathing the base of the pseudopodium. Pseudopodia to 2 mm long, straight. Capsule dark brown except for a pale apex, globose, to 1.2 mm long before dehiscence, opening by 4–6 longitudinal slits. Median exothecial cells to 20 µm wide, 2–3: 1, with thick and pitted lateral walls but thin transverse walls. Exothecial cells along lines of eventual capsule dehiscence more elongate and narrow in 1–2 irregular rows. Exothecial cells at capsule apex isodiametric and thick walled, somewhat smaller than median cells. Stomates absent. Spores to 20 µm , smooth, with trilete mark.
Our only California specimens of A. nivalis were collected at high elevations in Mt. Lassen National Park. All these plants seem to be male and so the sporophyte description is taken from plants originating in Washington State.
|Illustrations||Malcolm et al. 2009 p. 29; Ignatov and Ignatova 2003; Lawton 1971; Murray 1988; Smith 1978.|
|Vouchers||Shasta Co.: Redding Peak near Cliff Lake, Lassen Volcanic National Park, Showers 3580 (UC) [confirmed by Murray].|