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flat-rock grimmia, oval dry rock moss

Habit Plants in loose tufts, dark green to brownish black. Plants in robust, loose, arched-ascending, readily disintegrating patches, brownish green distally, blackish proximally.
Stems

1–3 cm.

5–10 cm, central strand absent.

Gemmae

absent.

Leaves

ovate-lanceolate from an ovate base, 1.7–4 × 0.4–0.8 mm, both margins plane, incurved distally, intermarginal bands absent, awn 0.5–1 mm, not decurrent, typically narrowly attached, acute, costa narrow proximally;

basal juxtacostal laminal cells usually elongate (sometimes short-rectangular), usually sinuose, and usually with thick lateral walls;

basal marginal laminal cells quadrate to long-rectangular, straight, with thick transverse and thin lateral walls, green, not to distinctly hyaline;

medial laminal cells rounded to quadrate, straight, thick-walled;

distal laminal cells 2-stratose, quadrate, thick-walled.

loosely appressed when dry, patent when moist, broadly ovate-lanceolate, tapering to an acute, slightly toothed apex, 2–3 × 0.4–0.6 mm, keeled, margins recurved on both sides, awns absent, costa stout, with two abaxial lamellae (or wings) forming parallel ridges along its length;

basal juxtacostal laminal cells yellow, linear, sinuose, thick-walled;

basal marginal laminal cells quadrate to short-rectangular, slightly thick-walled;

medial laminal cells quadrate to rectangular, sinuous, thick-walled;

distal laminal cells 1-stratose, margins 2-stratose.

Seta

straight, 4–6 mm.

cygneous to arcuate at maturity, flexuose when old, 3–5 mm.

Sexual condition

dioicous.

Capsule

occasionally present, exserted, yellow-brown, oblong-ovoid, exothecial cells short-rectangular, thin-walled, stomata present, annulus of 2–3 rows of rectangular, thick-walled cells, operculum long-rostrate, peristome solid, split in distal half.

occasionally present, exserted, obloid, yellowish green to yellowish brown, plicate when empty, exothecial cells thin-walled, annulus present, operculum rostrate, peristome teeth purple, divided nearly to base into two partly adhering segments, papillose.

Calyptra

cucullate.

mitrate.

Perichaetial

leaves enlarged.

Grimmia ovalis

Grimmia ramondii

Habitat Dry, exposed to partially shaded, acidic, sandstone, granite and basalt, montane to alpine Dry to damp acidic rock
Elevation (low to) moderate to high elevations (30-)1000-2500 m ((low to) moderate to high elevations (100-)3300-8200 ft) low to high elevations (0-2000 m) (low to high elevations (0-6600 ft))
Distribution
from FNA
AZ; CA; CO; ID; MN; MO; MT; NM; NV; NY; OR; PA; TX; UT; VA; WA; WY; AB; BC; ON; QC; YT; Greenland; Eurasia; Africa (Algeria, Morocco)
[WildflowerSearch map]
from FNA
AK; CA; ID; MI; MT; OR; WA; AB; BC; NF; NT; Greenland; Europe; Asia (China, Japan); n Africa
Discussion

Grimmia ovalis is common and widespread in high elevation sites in western North America from southern British Columbia along the Rocky Mountain corridor to southern New Mexico and south central California. H. A. Crum and L. E. Anderson (1981) rejected all reports of G. ovalis from eastern North America. However, we have seen specimens from that area, although scattered and rare. It is not surprising that the species occurs in the eastern part of the continent given that it is widespread across the Laurasian continental plates and in India. Outlier sites in the Yukon and southern Greenland connect the North American populations to those in Asia and Europe, respectively. In western North America, G. ovalis is most often confused with G. longirostris and G. laevigata. While superficially similar to G. longirostris, G. ovalis has concave leaves with plane margins and is dioicous, while G. longirostris has keeled leaves with a recurved margin and is autoicous. Other points of separation are discussed under G. longirostris. Typical specimens of G. ovalis are readily separated from G. laevigata by their ovate-lanceolate leaves with a well-defined ovate base and narrowly attached awns. However, both of these species are variable in leaf shape, and while the awn of G. ovalis is usually narrowly attached, sometimes it is quite broad and may border on being decurrent. These specimens can be identified by the width of the costa and the basal areolation. Grimmia ovalis has a costa that is narrow at the base, while G. laevigata has a distinctly broad costa covering up to 1/3 of the base. The basal marginal cells of G. ovalis are most often short- to long-rectangular and hyaline while those of G. laevigata are always oblate to quadrate and not hyaline. In eastern North America, specimens of G. ovalis have been misidentified as G. olneyi. Aside from seta and capsule differences, G. ovalis has rectangular basal marginal laminal cells and its basal juxtacostal cells are long-rectangular to elongate; see also under G. olneyi.

Based on identifications by Greven, W. A. Weber et al. (2003) reported Grimmia bernoullii in the United States. That species differs from G. ovalis by its more ovate leaves without shoulders and with plane margins, costa broad at the base and disappearing in mid leaf, and sporophytically by its ellipsoid capsule with long-rostrate, straight operculum, and mitrate calyptra. Hastings has examined duplicate specimens from Missouri of those cited by Weber et al. and has determined that they do not deviate significantly from G. ovalis, having rather narrow leaves, costa narrow at the base and remaining strong in mid leaf, and with many leaves having incurved margins. The specimens were sterile and therefore sporophytic characters could not be determined. Based on these observations Hastings excludes G. bernoullii from the North American flora, although Greven would still retain the species.

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

Grimmia ramondii occurs near sea level in arctic areas and along the West Coast. In the latter region, however, it is more common in mid-elevation montane sites and may also be found above the tree line. It differs from most Grimmia species by its lack of awns, winged costa, and tall, loose growth form. At first sight, G. ramondii has the habit of a Racomitrium. However, the sporophyte has an arcuate rather than straight seta, and the capsules are striate rather than smooth. Because of its habit and the absence of a central strand, K. G. Limpricht ([1885–]1890–1903, vol. 1) placed it, together with G. hartmanii and G. atrata, in Dryptodon, a genus intermediate between Grimmia and Racomitrium. There are many other Grimmia species, however, without a central strand, and G. hartmanii and G. atrata have already been removed from Dryptodon, so there is no reason to maintain that monotypic genus. Grimmia ramondii may be confused with G. hartmanii and G. elatior. However, the lack of awns, the Racomitrioideae-like areolation, and the distinct costal wings distinguish it easily from those species.

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

Source FNA vol. 27, p. 244. FNA vol. 27, p. 256.
Parent taxa Grimmiaceae > subfam. Grimmioideae > Grimmia > subg. Litoneuron Grimmiaceae > subfam. Grimmioideae > Grimmia > subg. Rhabdogrimmia
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. 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. reflexidens, G. serrana, G. sessitana, G. shastae, G. teretinervis, G. torquata, G. trichophylla, G. unicolor
Synonyms Dicranum ovale, G. commutata, G. ovata, G. ovata var. gracilis Pterigynandrum ramondii, Dryptodon patens, G. curvata, Racomitrium patens
Name authority (Hedwig) Lindberg: Acta Soc. Sci. Fenn. 10: 75. (1871) (Lamarck & De Candolle) Margadant: Lindbergia 1: 128. (1972)
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