Grimmia trichophylla
Grimmia serrana
grimmia dry rock moss, hair-point grimmia
2–4 cm, central strand present.
to 3 cm.
clusters occasionally present in distal leaf axils.
loosely appressed, slightly twisted when dry, erecto-patent when moist, lanceolate to oblong-lanceolate, tapering to acute apex, 2–3.5 × 0.3–0.4 mm, usually sharply keeled, margins recurved on one or both sides, plane to erect distally, awns variable, short to long, smooth to denticulate, not conspicuously flattened at base, costa firm, projecting on abaxial side;
basal juxtacostal laminal cells long-rectangular (rarely short-rectangular), ± nodulose, thick-walled;
basal marginal laminal cells short- to long-rectangular, with thickened transverse walls;
medial laminal cells quadrate to short-rectangular, slightly sinuose, thick-walled;
distal laminal cells 1-stratose, occasionally with 2-stratose ridges.
ovate-lanceolate from an ovate base, 2.5–3.5 × 0.6–0.7 mm, both margins plane, costa-like inter-marginal bands 2–4(–5)-stratose, awn to 1 mm, not decurrent, narrowly attached, acuminate, costa narrow proximally;
basal juxtacostal laminal cells short- to long-rectangular, sinuose, thick lateral-walled, dense;
basal marginal laminal cells quadrate to short-rectangular, sinuose, thick lateral-walled, not hyaline;
medial laminal cells quadrate, slightly sinuose, thick-walled;
distal laminal cells 1–3-stratose, oblate to rectangular, thick-walled.
arcuate, 2–4 mm.
straight to slightly arcuate, to 3.5 mm.
dioicous.
occasionally present, exserted, oblong-ovoid, yellowish green to stramineous, striate when dry, exothecial cells thin-walled, annulus present, operculum rostrate, peristome teeth yellowish, papillose, deeply split and perforated.
occasionally present, exserted, pale yellow, ovoid, exothecial cells oblong, thin-walled, stomata absent, annulus of 1–2 rows of quadrate, thick-walled cells, operculum short straight, peristome fully developed, not perforate, not split.
mitrate.
cucullate.
leaves enlarged.
Grimmia trichophylla
Grimmia serrana
In North America, Grimmia trichophylla is principally a lowland species, occurring in the mountains up to about 1000 m., rarely higher. In the Southern Hemisphere, it may be found up to 4000 m. In New Zealand, the species is common, and in contrast to G. trichophylla in North America, frequently bears capsules. The New Zealand plants are usually smaller than American specimens, and the leaves are frequently contorted. The nearly cosmopolitan G. trichophylla has many phenotypes, and numerous subspecies and varieties have been described. In damp and shaded habitats, the awns may be short, just as in dry unfavorable habitats at high altitudes, where stunted specimens may occur with small, short leaves and reduced awns, or even with muticous leaves. Grimmia trichophylla has frequently been confused with related species such as 36. G. muehlenbeckii and 34. G. lisae (see discussions thereunder for identification details). Robust forms of G. trichophylla have been mistaken for G. austrofunalis (H. C. Greven 1997, 2003), which does not occur in North America. Although some of those plants have leaves of equal length along the stem, characteristic of G. austrofunalis, they also have both leaf margins recurved, and the medial and outer basal laminal cells are longer and more robust than in that species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
According to the original description, Grimmia serrana is known only from “localities along the western slope of the Sierra Nevada and two occurrences in the northern Coast Range.” Despite its limited distribution, H. C. Greven (2003) found it to be quite common in the area. With its thick, concave leaves with plane margins and flat costa, G. serrana is best placed in subg. Litoneuron. This is further supported by a number of other features shared by, but not unique to, all members of that subgenus, including a well-developed stem central strand, dioicous sexuality, and long-exserted capsule with a multi-layered, thick-walled annulus. Grimmia serrana is most readily identified by a prominent, costa-like, multi-layered band of cells that run along the laminal margin distally and become submarginal proximally. This inflated band is unique to this species and readily separates it from all other members of subg. Litoneuron. As stated by Muñoz et al., G. serrana is most likely to be confused with G. ovalis. Both are robust species with ovate-lanceolate leaves from an ovate base. However, the prominent intermarginal bands of G. serrana will readily separate these species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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