Grimmia longirostris |
Grimmia pulvinata |
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grimmia dry rock moss |
grey-cushion grimmia, pulvinate dry rock moss |
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Habit | Plants in compact cushions, yellow-green to dark olivaceous. | Plants in hemispherical hoary cushions, grayish green. |
Stems | 1–3 cm, central strand strong. |
1–3 cm, central strand present. |
Gemmae | absent. |
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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. |
flexuose when dry, erect when moist, lanceolate, 1–1.7 × 0.3–0.6 mm, keeled, margin recurved on both sides nearly from base to apex, rarely only one margin recurved, abruptly contracted into short to long, smooth to denticulate awn, costa weak proximally, projecting on abaxial side; basal juxtacostal laminal cells quadrate to short-rectangular, thin-walled; basal marginal laminal cells quadrate to short-rectangular, thin- or thick-walled; medial laminal cells rounded-quadrate, slightly sinuose, thin-walled; distal laminal cells 1-stratose, margins 2-stratose. |
Seta | straight, (1–)2–4 mm. |
arcuate, 3–4 mm. |
Sexual condition | cladautoicous, perichaetial leaves not enlarged. |
autoicous. |
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, exserted, ellipsoid to obloid, brownish and ribbed when empty and dry, exothecial cells thin-walled, annulus present, operculum rostrate, peristome teeth reddish, fully-developed, papillose. |
Calyptra | mitrate. |
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Grimmia longirostris |
Grimmia pulvinata |
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Habitat | Exposed, dry, acidic granite and quartzite | Various substrates, from acidic to basic rock, old mortar, tree trunks |
Elevation | low to high eleavations (100-3100 m) [low to high eleavations (300-10200 ft)] | low to high elevations (0-3000 m) [low to high elevations (0-9800 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
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AZ; CA; CO; IA; ID; IN; KS; MD; MI; MO; MS; MT; NM; NV; OK; OR; SD; TX; UT; WA; WY; AB; BC; ON; Mexico; South America (Argentina, Chile, Uruguay); Eurasia; Africa; Pacific Islands (New Zealand); Australia
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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.) |
Grimmia pulvinata is the most common species of the genus. It has a nearly cosmopolitan distribution, and is a pioneer on various substrates, even on the trunks of trees. However, in the eastern part of North America, it occurs only in a few scattered localities (H. A. Crum 1977). It is easily recognized by its neat hemispherical cushions with abundant capsules. It may be confused with G. orbicularis, which grows in similar habitats and is known to co-occur with G. pulvinata. However, as discussed under G. orbicularis, it differs in gametophytic as well as sporophytic characters. Some forms with more acuminate leaf tips may be confused with G. trichophylla, but the thin-walled, short-rectangular basal cells and the small, rounded mid leaf cells distinguish G. pulvinata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 27, p. 239. | FNA vol. 27, p. 255. |
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 | Fissidens pulvinatus, G. decipiens var. hendersonii, G. indianensis, G. pulvinata var. africana, G. subcurvula, G. trichophylla var. indianensis |
Name authority | Hooker: Musci Exot. 1: plate 62. (1818) | (Hedwig) Smith: in J. E. Smith et al., Engl. Bot. 24: plate 1728. (1807) |
Web links |