Dendroalsia abietina (Hook.) Britt.
Proc. Amer. Acad. Arts Sci. 3: 185. 1855. -- Neckera abietina Hook., Musci Exot. 1, tab. 7. 1818.
Leptodon circinatus Sull., Rep. Expl. Surv. Railr. R. Bot. 4(5): 189. pl. 1. 1856 (1857).
Plants plumose-dendroid in loose to dense, rather deep wefts; dark green to brownish green. Primary Stems (stolons) to 30 cm long, prostrate, forming a densely rhizoidal tangled mat. Stolon leaves long lanceolate with a long and narrow acumen. Secondary stems to 25 cm high, ascending or sometimes arching and anchored distally, pinnately or occasionally bipinnately branched in a single plane with most branch apices not much attenuated. Branches typically circinately coiled when dry, sometimes flagelliform at apices. Paraphyllia forming a dense felt on main axis and larger branches except near abaxial leaf insertion, variable and ranging from unlobed, lanceolate to pinnately or palmately deeply lobed, sometimes even filamentous and unlobed. Stipe Leaves concave, lightly plicate, imbricate when dry, erect-spreading when moist; ovate to ovate-lanceolate, to 3.5 mm,; 3–5: 1, rather narrowly decurrent. Branch leaves distinctly pentastichous, concave and imbricate, not at all plicate, erect to weakly spreading, ovate to ovate-lanceolate, to 2.5 mm, 2–3: 1, narrowly decurrent. Margins recurved below or sometimes recurved nearly to apex, decurrent at base, serrulate above the middle except at the sharply dentate apex. Costa extending within several cells of apex, dorsally cristate in distal portions. Median Laminal cells elliptic to rhomboidal, 5–8 µm wide, 2–4: 1, thick-walled (lumen/wall ratio about 5: 1), strongly to lightly pitted, strongly prorate especially near the apex. Apical cells often nearly isodiametric. Alar cells thick-walled and numerous, quadrate to transversely elongate, to 12 µm broad, thick-walled, extending nearly to costa and an equal distance up the margin, Rhizoids red-brown, extensively branched, to 6 µm in diameter, smooth, inserted in a single series completely across the abaxial leaf base. Axillary hairs to 100 µm, with 1–4 basal brown cells and 3 distal ones, not offset from leaf insertion. Rhizoids red-brown, extensively branched, to 6 µm in diameter, smooth, inserted in a single series completely across the abaxial leaf base. Pseudoparaphyllia lanceolate and erect, similar to the larger paraphyllia.
Sexuality dioicous with male plants somewhat smaller than females, usually located strongly admixed with the females. Perigonia nearly spherical, bud-like, densely cloaking the main axis and larger branches. Perichaetia on main axis, the leaves ovate to lanceolate, to 2.5 mm long, mostly ecostate, strongly convolute and investing almost all the seta. Setae pale-brown, to 3 mm long, erect, smooth. Capsule exserted, erect to slightly inclined, nearly symmetric, brown, cylindric, to 2.5 mm, 2–3: 1, not distorted or sulcate when dry; Exothecial cells irregularly isodiametric, to 40 µm, with the walls to 5 µm wide and evenly thickened. Stomata restricted to neck. Operculum inclined short-rostrate, about 1/3 as long as urn. Annulus 2–3 cells wide, tardily deciduous Exostome teeth 16, erect and white, linear-lanceolate, 10–15: 1, papillose. Endostome segments narrow, about as long as exostome and with low basal membrane and no cilia. Calyptra cucullate, smooth or with a few hairs. Spores spherical, 15–20 µm, papillose, light brown.
This is one of the most easily recognised mosses in California. The large, pinnately branched erect axes curl downwardly when dry in a manner reminiscent of the fingers of a clenched fist. Microscopically, it can be recognised by the combination of prorate cells, abundant branched paraphyllia, and the erect and plumose growth habit. D. abietina closely parallels the distribution of Antitrichia californica. In general, Antitrichia californica grows on the bases of oak trees, especially deciduous ones, while Dendroalsia abietina is more common on the trunks. Like most of the epiphytic plants of California, either of these two species may frequently occur on rocks.