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grimmia dry rock moss

Olney's dry rock moss

Habit Plants in compact cushions, yellow-green to dark olivaceous. Plants in flat patches, dark green to brownish black.
Stems

1–3 cm, central strand strong.

1–2 cm.

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.

narrowly ovate-lanceolate from an ovate base, 2–3 × 0.4–0.8 mm, both margins incurved, intermarginal bands absent, awn 0.1–0.5 mm, not decurrent, acute, costa narrow proximally;

basal juxtacostal laminal cells quadrate to short-rectangular, straight, thick lateral walls, green;

basal marginal laminal cells quadrate, straight, thick transverse and thin lateral walls, green, hyaline;

medial laminal cells quadrate, slightly thick-walled;

distal laminal cells 2–4 stratose, rounded, thick-walled.

Seta

straight, (1–)2–4 mm.

sigmoid, 3–4 mm.

Sexual condition

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.

occasionally present, exserted, 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 perforate in distal half, split in distal half.

Calyptra

cucullate.

Perichaetial

leaves not enlarged.

Grimmia longirostris

Grimmia olneyi

Habitat Exposed, dry, acidic granite and quartzite Cracks and exposed faces of dry to periodically wet, acidic or calcareous rocks, commonly along streams or splash zones of lake shores
Elevation low to high eleavations (100-3100 m) [low to high eleavations (300-10200 ft)] low to moderate elevations (20-600 m) [low to moderate elevations (70-2000 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
AR; CT; DE; MA; ME; MI; MO; NC; NH; NJ; NY; PA; RI; TN; VA; VT; NS; ON
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 olneyi is endemic to eastern North America, with its center of distribution along the Appalachians from the New England states to North Carolina and eastern Tennessee. A disjunct population occurs on the Ozark Plateau of Missouri and Arkansas. Unlike G. unicolor, G. olneyi is tolerant of calcareous rocks and is able to occupy drier sites. Because of its sigmoid seta and somewhat wrinkled capsule, it is usually placed in subg. Rhabdogrimmia. However, the seta of G. olneyi is usually only somewhat sigmoid and is rarely arcuate. Further, its capsules only become wrinkled when dry, whereas the members of subg. Rhabdogrimmia typically have plicate capsules whether dry or turgid. In fact, specimens of G. olneyi are most commonly misidentified as either G. ovalis or G. laevigata, in subg. Litoneuron. The seta and capsule of G. olneyi are at the extremes of both subgenera. However, the general habit of the plants and their leaf structure suggests a close relationship with G. ovalis and G. unicolor.

Grimmia olneyi and G. laevigata have broadly overlapping distributions in eastern North America, where many specimens of G. olneyi have been misidentified as G. laevigata. Typical specimens of G. olneyi are readily separated from G. laevigata. However, some leaves on a stem of G. laevigata may have defined ovate bases with narrowly decurrent awns. These specimens will resemble G. olneyi. However, the costa of G. olneyi is always narrow at the base, while that of G. laevigata becomes broad at the base, occupying up to 1/3 of the lamina, and the costa grades gradually into the basal laminal cells. Furthermore, G. olneyi has quadrate to short-rectangular basal juxtacostal cells, while those of G. laevigata are elongate, almost resembling costal cells. Grimmia olneyi most closely resembles G. ovalis. Both have ovate lanceolate leaves from an ovate base, with a narrow distal lamina that is channelled, ending in a narrowly attached, long and toothed awn. The costa is narrow proximally in both species. However, they are otherwise quite distinct. Aside from the sigmoid seta and slightly wrinkled dry capsule of G. olneyi, its basal juxtacostal laminal cells are shorter and straighter than those of G. ovalis and its basal marginal cells are quadrate while those of G. ovalis are mostly rectangular. Geographical distribution has also been used to separate these species; H. A. Crum and L. E. Anderson (1981) rejected all reports of G. ovalis from eastern North America. However, we have seen a number of specimens of it from there and conclude that geography alone is not a reliable basis on which to differentiate these species.

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

Source FNA vol. 27, p. 239. FNA vol. 27, p. 244.
Parent taxa Grimmiaceae > subfam. Grimmioideae > Grimmia > subg. Guembelia Grimmiaceae > subfam. Grimmioideae > Grimmia > subg. Litoneuron
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. 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 G. austinii
Name authority Hooker: Musci Exot. 1: plate 62. (1818) Sullivant: in W. S. Sullivant and C. L. Lesquereux, Musc. Bor.-Amer., 141. (1857)
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