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grimmia dry rock moss

grimmia dry rock moss

Habit Plants in compact cushions, yellow-green to dark olivaceous. Plants in variable loose patches, dark green to black, frequently rust colored proximally.
Stems

1–3 cm, central strand strong.

2–7 cm, central strand absent.

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 ligulate, 1.5–3 × 0.3–0.6 mm, keeled, margins recurved proximally, incurved distally, tapering to a blunt cucullate apex, muticous, costal transverse section prominent, usually semicircular;

basal juxtacostal laminal cells rectangular, straight to slightly sinuose walled;

basal marginal laminal cells in 1–3 rows quadrate, hyaline with straight to slightly sinuose, thick transverse walls;

medial laminal cells rectangular, nearly straight to sinuose or nodulose, thick-walled;

distal laminal cells 1-stratose with 2-stratose ridges, to completely 2-stratose.

Seta

straight, (1–)2–4 mm.

straight, 2–6 mm.

Sexual condition

cladautoicous, perichaetial leaves not enlarged.

dioicous, 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.

occasionally present, long-exserted, yellow-brown, oblong to cylindric, exothecial cells rectangular, thick-walled, annulus of 3–4 rows of rectangular, thick-walled cells, stomata present, operculum conic to rostrate, peristome present, fully-developed, perforated and split distally, weakly papillose.

Grimmia longirostris

Grimmia atrata

Habitat Exposed, dry, acidic granite and quartzite Damp, heavy-metal-bearing rock from the lowlands to the alpine
Elevation low to high eleavations (100-3100 m) [low to high eleavations (300-10200 ft)] moderate to high elevations (1100-2600 m) [moderate to high elevations (3600-8500 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
LB; YT; Greenland; South America (Bolivia); Eurasia
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 atrata is rare in North America, being known only from three widely scattered areas. It is known to geologists as one of the “copper-mosses,” i.e., it is an indicator of heavy-metal-bearing rock. Because it prefers damp gneiss and mica schists, the tufts are often orange inside on account of the presence of heavy-metal oxides. The placement of G. atrata has been problematic. Because of the curved distal leaves and the absence of awns, it does not immediately appear to be a Grimmia. As a result it has previously been placed in a separate genus, Dryptodon, intermediate between Grimmia and Racomitrium. Following Cao T. and D. H. Vitt (1986b), Hastings placed it in subg. Guembelia based on its thick, keeled leaves, long, straight setae, and smooth capsules. With its recurved margin, rectangular, thick-walled, sometimes sinuous basal laminal cells, prominent annulus, and mitrate calyptra, it would seem closest to the group including G. longirostris and G. pilifera. However, its large size and muticous, cucullate leaves, which are often ligulate, coupled with its preference for moist habitats, readily separate this species from other members of this group. Sterile specimens with 1-stratose laminae may be confused as belonging to the subg. Rhabdogrimmia. In densely shaded habitats, it grows in loose patches and the areolation shows a near absence of sinuosity. On dry rock, however, the plants have extremely thick, nodulose cell walls that place the species firmly in Grimmia.

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

Source FNA vol. 27, p. 239. FNA vol. 27, p. 241.
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. 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. sessitana, 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 Dryptodon atratus
Name authority Hooker: Musci Exot. 1: plate 62. (1818) Mielichhofer ex Hornschuch: Flora 2: 85. (1819)
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