Pseudocrossidium crinitum
Pseudocrossidium
pseudocrossidium moss
leaves ovate to short-lanceolate, 1.5–1.9 mm including the awn, distal margins strongly recurved to once revolute;
apex rounded-obtuse below the awn;
costa ending in a short awn, adaxial surface of costa at mid leaf concave, with 4 guide cells;
distal laminal cells 12–15 µm wide, 1:1.
leaves appressed and often spiraled when dry, weakly or widely spreading when moist; ovate or ligulate to lanceolate, adaxial surface channeled or grooved along costa;
base scarcely differentiated in shape to oblong;
distal margins recurved to broadly revolute or spiraled, entire or occasionally weakly denticulate near apex, occasionally differentiated as a photosynthetic organ of thin-walled, hollow-papillose cells;
apex acute to rounded;
costa often swollen medially, excurrent as a mucro or short awn, [adaxial outgrowths occasionally differentiated as a pad of filaments of uniseriate, papillose cells,] adaxial cells quadrate to shortly rectangular, in 2–5 rows;
transverse section usually reniform to circular, adaxial epidermis present, adaxial stereid band absent [present and small (usually of 1–2 cells)], guide cells 2–4(–6), in 1–2 layers, hydroid strand present, often multiple, occasionally absent, abaxial stereid band present, usually strong, crescentiform in section, abaxial epidermis present, often weak;
proximal cells differentiated medially, occasionally across leaf, rectangular, 2–6:1, walls of proximal cells thin to evenly thickened, occasionally porose, hyaline or occasionally orange;
distal medial cells subquadrate, often transversely elongated, 8–16(–18) µm wide, 1:1(–3), 1-stratose;
papillae crowded, hollow, occasionally platelike or 2-fid or multiplex, usually crowded, cell walls evenly thickened, weakly convex to bulging on both sides.
1–2 cm.
dioicous.
stegocarpous, theca elliptic to cylindric, occasionally curved, 1.6–3 mm, annulus of 2–4 rows of vesiculose cells, persistent;
peristome teeth 16, cleft to base or 32, linear, to once-twisted counterclockwise, occasionally straight;
operculum short- to long-conic or conic-rostrate.
cucullate.
8–12 µm.
asexual reproduction absent.
asexual reproduction by small gemmae, clavate, seldom present, borne on adaxial surface of costa.
terminal, inner leaves weakly differentiated or convolute-sheathing and enlarged, often awned.
laminal color reaction yellow to orange, occasionally with red blotches at mid leaf or above.
Pseudocrossidium crinitum
Pseudocrossidium
Pseudocrossidium crinitum, when the awn is short, can be distinguished from P. replicatum (forms of which may have strongly mucronate leaf apices) by the large area of differentiated parenchymatous cells on the abaxial lateral surface of the costa on both sides adjacent to the laminal insertion on the costa, easily seen in section at mid leaf and often deep yellow in color, appearing as a row of ocelli; the leaf marginal cells are very thin-walled. This essentially southern species reaches its northern range extension in western United States E. B. Bartram 1924; R. H. Zander 1993). An exceptionally robust collection of P. crinitum from Mexico (Puebla, Azumbilla, Zander 4899, BUF) has two layers of guide cells in the costa, but this is very unusual.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 16 (4 in the flora).
Pseudocrossidium is characterized by the commonly ovate to elliptic leaves, rather small distal laminal cells, the small size or absence of the adaxial costal stereid band, the crescent shape of the abaxial stereid band, and lamina yellow or orange (with occasional red spots) in KOH (R. H. Zander 1993). Most but not all species have some elaboration of the cells of the adaxial epidermis or marginal cells of the leaf as photosynthetic organs or enlargement of the perichaetial leaves. The small distal laminal cells and yellow or orange KOH reaction will distinguish the species from Syntrichia, which is red in KOH, and has a similar costal anatomy but lacks an abaxial epidermis. See B. C. Tan et al. (1981) and Zander (1979, 1981, 1994n) for extensive discussion of the taxonomy and distribution of Pseudocrossidium in the Americas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaves long-mucronate to long-awned | → 2 |
1. Leaves merely apiculate to short-mucronate | → 3 |
2. Leaves rounded-obtuse at base of awn; costa concave adaxially, with 4 guide cells. | P. crinitum |
2. Leaves narrowly acute at base of awn; costa convex adaxially, with 2 guide cells | P. hornschuchianum |
3. Plants coarse, leaves comparatively long, 1-1.5 mm, ligulate to oblong-lanceolate, apex obtuse; costa concave adaxially, with (4-)6 guide cells. | P. replicatum |
3. Plants delicate, leaves short, 0.7-1.2 mm, ovate to ovate-deltoid, apex broadly acute; costa convex adaxially, with 2-3 guide cells. | P. obtusulum |
CalFlora
WildflowerSearch
iNaturalist
USDA Plants Database
