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American dry rock moss

Habit Plants in compact hairy cushions, grayish green. Plants in hoary tufts, dark green to brown.
Stems

1–2 cm, central strand absent.

0.5–1.5 cm.

Leaves

ovate to oblong-lanceolate, 0.1–1.15 × 0.3–0.5 mm, keeled, not plicate, margins plane, awns 1–2 mm, very long, smooth to slightly denticulate, flattened basally, long-decurrent, costal transverse section prominent, semi-circular;

basal juxtacostal laminal cells rectangular, sometimes nodulose, thin- to thick-walled;

basal marginal laminal cells rectangular with thickened transverse walls, pellucid in 2–4 rows;

medial laminal cells rounded-quadrate, slightly sinuose, thick-walled;

distal laminal cells yellowish green, 1-stratose with 2-stratose ridges, 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 to arcuate, 0.6–1 mm.

Sexual condition

dioicous, perichaetial leaves enlarged.

gonioautoicous.

Capsule

absent in northern hemisphere material, emergent to shortly exserted, yellowish brown, oblate, exothecial cells irregularly short-rectangular, thin-walled, stomata absent, annulus of 1 row of quadrate, thick-walled cells, operculum mammillate to rostrate, peristome present, nearly fully-developed, split and perforated only in apex, papillose.]

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.

[seta straight, 1.5–2 mm.

Grimmia reflexidens

Grimmia americana

Habitat Dry acidic rock Calcareous rock
Elevation low [to moderate] elevations (50[-300] m) (low [to moderate] elevations (200[-1000] ft)) moderate to high elevations (ca. 1600 m) (moderate to high elevations (ca. 5200 ft))
Distribution
from FNA
NF; South America (Argentina, Chile); Atlantic Islands (Iceland); Pacific Islands (New Zealand); Australia
from FNA
AZ; NV; TX
Discussion

Of conservation concern.

Previous to its discovery in Iceland, as Grimmia grisea (H. C. Greven 1998), G. reflexidens was known from only the Southern Hemisphere. It had previously been collected east of East Bay, Newfoundland, now the only known locality in North America, but was not recognized as G. reflexidens. The latter is similar to G. asperitricha Dixon & Sainsbury of New Zealand, and the two species have been confused by G. O. K. Sainsbury (1945) as well as by R. Ochyra (1993). J. Muñoz (1998b) synonymized G. reflexidens with G. sessitana. However, the former is readily separated from the latter by: (1) enlarged perichaetial leaves, (2) decurrent awns, (3) non-bulging laminal cells, and (4) dioicous sexual condition. Capsules are unknown from Northern Hemisphere material, but G. reflexidens lacks stomata while they are present for G. sessitana. Although G. reflexidens and G. teretinervis both have decurrent awns they are easily separated by a number of characters: G. reflexidens grows in compact cushions, has long awns, and a semicircular costa; G. teretinervis grows in loose clumps, is hyaline-tipped to short-awned, and has a unique costa that is distally almost completely circular in transverse section.

(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. 238. FNA vol. 27, p. 232.
Parent taxa Grimmiaceae > subfam. Grimmioideae > Grimmia > subg. Guembelia Grimmiaceae > subfam. Grimmioideae > Grimmia > subg. Grimmia
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. 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. serrana, G. sessitana, G. shastae, G. teretinervis, G. torquata, G. trichophylla, G. unicolor
G. alpestris, 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. sessitana, G. shastae, G. teretinervis, G. torquata, G. trichophylla, G. unicolor
Synonyms G. grisea
Name authority Müller Hal.: Syn. Musc. Frond. 1: 795. (1849) E. B. Bartram: Bryologist 32: 8, fig. 1. (1929)
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