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grimmia dry rock moss

Habit Plants in compact cushions, yellow-green to dark olivaceous. Plants in dense patches, dark green, brown-green, sometimes almost black.
Stems

1–3 cm, central strand strong.

0.5–1 cm, central strand strong.

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.

lanceolate to ovate-lanceolate, 1–1.8 × 0.2–0.6 mm, keeled, not plicate, one margin commonly recurved, sometimes both plane, awn 0.3–0.8 mm, costal transverse section prominent, semicircular;

basal juxtacostal laminal cells rectangular to elongate, straight, thin-walled;

basal marginal laminal cells short- to long-rectangular, straight, thick transverse and thin lateral walls, hyaline or not;

medial laminal cells quadrate, sinuose, thick-walled;

distal laminal cells 1-stratose, often bulging, marginal cells widely 2-stratose, often bulging.

Seta

straight, (1–)2–4 mm.

straight, 1–2.5 mm.

Sexual condition

cladautoicous, perichaetial leaves not enlarged.

cladautoicous, perichaetial leaves not enlarged.

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, yellow, ovoid to elliptic, exothecial cells short-rectangular, thin-walled, stomata present, annulus of 1 row of quadrate, thick-walled cells, operculum conic, usually with a short obtuse beak, peristome present, fully-developed, split or solid in distal half.

Grimmia longirostris

Grimmia sessitana

Habitat Exposed, dry, acidic granite and quartzite Exposed or sheltered, moist, acidic granite and sandstone, alpine
Elevation low to high eleavations (100-3100 m) [low to high eleavations (300-10200 ft)] moderate to high elevations (1100-3900 m) [moderate to high elevations (3600-12800 ft)]
Distribution
from FNA
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
[WildflowerSearch map]
from FNA
AK; AZ; CA; CO; ID; MT; NH; NM; NV; NY; OR; UT; WA; WY; AB; BC; NL; NT; QC; YT; Africa (Kenya, South Africa, Uganda); Greenland; Eurasia; South America (Argentina, Chile); Antarctic
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 sessitana is widely distributed in high elevation sites throughout western North America, principally in mountains forming the continental divide, but also in the northern Sierra Nevada and the coastal range of Oregon and Washington. It is rare in eastern North America, but occurs in the northern Appalachians of the United States, on the Gaspé Peninsula of Quebec, and in Labrador. This is the least xerophilous member of the group; specimens have been collected in runoff zones from late-lying snow patches in the alpine. It is very rare in the dry interior mountains of the American Southwest. Grimmia sessitana is gametophytically variable and often difficult to identify with certainty. The presence of stomata and the autoicous condition separate this species from both G. montana and G. alpestris, which are the most common misidentifications. Confirming the presence or absence of stomata requires careful dissection of the capsule, including the neck, as the stomata are often just distal to the attachment of the seta. Sexuality can be difficult to determine, as G. sessitana is cladautoicous. If one leaf margin is recurved this will confirm the identification. However, some specimens may have plane margins. The presence of bulging-mammillose cells should separate G. sessitana from G. montana, but a significant number of specimens of G. sessitana have only weakly bulging laminal cells. Thus, specimens with capsules and antheridia are usually identifiable, while sterile specimens may be problematic. The other species that is often confused with G. sessitana is G. donniana. Both species have capsules with stomata and are autoicous. However, G. donniana very consistently has leaves with plane margins, uniform basal areolation with hyaline, narrowly rectangular thin-walled cells, and laminal cells that do not bulge. Grimmia sessitana appeared in H. A. Crum and L. E. Anderson’s (1981) flora of eastern North America as G. tenerrima. E. Lawton (1971), who accepted autiocous specimens in the concept of G. alpestris, excluded G. sessitana from the flora of the Pacific Northwest. J. Muñoz (1998b) put G. sessitana in synonymy with G. reflexidens but this is not correct.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 27, p. 239. FNA vol. 27, p. 237.
Parent taxa Grimmiaceae > subfam. Grimmioideae > Grimmia > subg. Guembelia Grimmiaceae > subfam. Grimmioideae > Grimmia > subg. Guembelia
Sibling taxa
G. alpestris, G. americana, G. anodon, G. anomala, G. arizonae, G. atrata, G. attenuata, G. brittoniae, G. caespiticia, G. crinitoleucophaea, G. donniana, G. elatior, G. elongata, G. funalis, G. hamulosa, G. hartmanii, G. incurva, G. laevigata, G. leibergii, G. lesherae, G. lisae, G. mariniana, G. mollis, G. montana, G. moxleyi, G. muehlenbeckii, G. nevadensis, G. olneyi, G. orbicularis, G. ovalis, G. pilifera, G. plagiopodia, G. pulvinata, G. ramondii, G. reflexidens, G. serrana, G. sessitana, G. shastae, G. teretinervis, G. torquata, G. trichophylla, G. unicolor
G. alpestris, G. americana, G. anodon, G. anomala, G. arizonae, G. atrata, G. attenuata, G. brittoniae, G. caespiticia, G. crinitoleucophaea, G. donniana, G. elatior, G. elongata, G. funalis, G. hamulosa, G. hartmanii, G. incurva, G. laevigata, G. leibergii, G. lesherae, G. lisae, G. longirostris, G. mariniana, G. mollis, G. montana, G. moxleyi, G. muehlenbeckii, G. nevadensis, G. olneyi, G. orbicularis, G. ovalis, G. pilifera, G. plagiopodia, G. pulvinata, G. ramondii, G. reflexidens, G. serrana, G. shastae, G. teretinervis, G. torquata, G. trichophylla, G. unicolor
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 G. subpapillinervis, G. tenerrima
Name authority Hooker: Musci Exot. 1: plate 62. (1818) De Notaris: Atti Reale Univ. Genova 1: 704. (1869)
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