Grimmia longirostris |
Grimmia americana |
|
---|---|---|
grimmia dry rock moss |
American dry rock moss |
|
Habit | Plants in compact cushions, yellow-green to dark olivaceous. | Plants in hoary tufts, dark green to brown. |
Stems | 1–3 cm, central strand strong. |
0.5–1.5 cm. |
Leaves | ovate-lanceolate, 1.5–3 × 0.6–0.7 mm, keeled, one margin recurved proximally, not sheathing, awn 0.5–1.5 mm, costal transverse section prominent, reniform; basal juxtacostal laminal cells long-rectangular to linear, sinuose, thick-walled; basal marginal laminal cells short-rectangular, straight, with thick transverse and thin lateral walls, hyaline; medial laminal cells short-rectangular, sinuose, thick-walled; distal laminal cells 2-stratose, not bulging, marginal cells 2-stratose, not bulging. |
oblong-ovate to oblong-lanceolate, 1.5–2 × 0.5–0.9 mm, concave, awn to 1 mm; basal juxtacostal laminal cells quadrate to short-rectangular, straight, thick-walled; basal marginal laminal cells quadrate to long-rectangular, straight, thick-walled, medial laminal cells rounded-quadrate, slightly thick-walled; distal laminal cells 2-stratose, marginal cells 2-stratose. |
Seta | straight, (1–)2–4 mm. |
straight to arcuate, 0.6–1 mm. |
Sexual condition | cladautoicous, perichaetial leaves not enlarged. |
gonioautoicous. |
Capsule | usually present, (emergent to) exserted, yellow, oblong-ovoid to cylindric, exothecial cells short- to long-rectangular, thin-walled, stomata present in 2–3 rows, annulus of 2 rows of rectangular, thick-walled cells, operculum long-rostrate, peristome present, fully-developed, split and perforate in distal half. |
usually present, exothecial cells thick-walled, annulus of 2–3 rows of rectangular, thin-walled cells, revoluble, operculum rostellate, peristome present, fully developed, perforated and split in most distal part, weakly papillose. |
Grimmia longirostris |
Grimmia americana |
|
Habitat | Exposed, dry, acidic granite and quartzite | Calcareous rock |
Elevation | low to high eleavations (100-3100 m) [low to high eleavations (300-10200 ft)] | moderate to high elevations (ca. 1600 m) [moderate to high elevations (ca. 5200 ft)] |
Distribution |
AK; AZ; CA; CO; ID; ME; MN; MT; NC; NH; NM; NV; OK; OR; SD; TX; UT; VT; WA; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; QC; SK; YT; Mexico; South America; Africa; Pacific Islands; Greenland; Eurasia; Central America (Costa Rica, Guatemala, Honduras); Australia
|
AZ; NV; TX |
Discussion | Grimmia longirostris is one of the most common species of the genus. It is most common in the eastern ranges of the Rocky Mountains, ranging from western Texas through the Canadian Rockies, and throughout much of Alaska. It is widely distributed in the Canadian sub-Arctic and Arctic, and is known from Greenland. With the exception of disjunct sites in Oklahoma and North Carolina, it is absent in the American Great Plains and Southeast. These latter areas are largely composed of calcareous rocks, a substrate avoided by G. longirostris. It is rare in coastal areas, becoming more common inland. As Grimmia affinis, G. longirostris has commonly been placed as a subspecies of G. ovalis. Despite G. Sayre’s (1951) resolution of the differences between these taxa, a large proportion of specimens in major herbaria in North America that are named G. ovalis are actually G. longirostris. However, G. ovalis is dioicous and has leaves with plane margins that are broadly concave distally, usually with a distinct ovate base and well-defined shoulders. In contrast, G. longirostris is autoicous, and has leaves with one recurved margin, that are narrowly keeled distally, with a poorly defined basal region, often without a distinct shoulder. These characters clearly separate these two taxa at the specific level. Hastings puts G. longirostris into a group that also includes G. arizonae and G. pilifera. Grimmia longirostris is separated from those two species by non-sheathing leaf bases, usually long-exserted capsules, and cladautiocous sexuality. Grimmia longirostris is further separated from G. pilifera by having a stem with a distinct central strand and a thin epidermis, a costal transverse section that is typically reniform, and leaves that are recurved on only one margin. Rare specimens of G. longirostris with immersed capsules in the American Southwest may be almost indistinguishable from G. arizonae. In extremely xeric environments, specimens become friable and break into individual strands, making determination of the cladautiocous sexuality impossible. In these circumstances identification will always be uncertain. However, the leaves of G. longirostris are not sheathing; they are only loosely attached to the stem and usually can be peeled off intact. In contrast, the leaves of G. arizonae are sheathing and strongly attached to the stem; they often break at the base when trying to remove them. The costal transverse sections of G. longirostris are characteristically reniform (J. Muñoz 1998) while those of G. arizonae are usually semicircular. However, gradations from semicircular to reniform are not uncommon. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Grimmia americana is a rare endemic, currently known only from three sites. Until 1999, the species was known only from its type locality in Jeff Davis County of western Texas. A second locality was reported by J. Muñoz (1999) in Arizona and a third site by L. R. Stark et al. (2002) in Nevada. Thus, it is reasonable to expect G. americana to occur also in southern New Mexico. It is recognized as a member of subg. Grimmia by its immersed, ventricose capsule, with a short mitrate calyptra and eccentric seta attachment. The overall habit of the species also is similar to that of the other members of the subgenus. However, its basal laminal cells are thick-walled while other members have thin cell walls. H. A. Crum (1994c) implied that G. americana is similar to G. anodon, but the former is readily separated by its fully developed, perforated peristome, rostellate operculum, and thick-walled basal laminal cells. Grimmia crinitoleucophaea, also most commonly found in the American Southwest, is dioicous, has a rudimentary peristome, and thin-walled basal laminal cells. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 27, p. 239. | FNA vol. 27, p. 232. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | G. affinis, G. arctophila subsp. labradorica, G. catalinensis, G. catalinensis var. mutica, G. elata, G. ortholoma, G. ovalis var. affinis, G. ovata var. affinis, G. ovateoformis | |
Name authority | Hooker: Musci Exot. 1: plate 62. (1818) | E. B. Bartram: Bryologist 32: 8, fig. 1. (1929) |
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