Grimmia reflexidens
Grimmia hamulosa
grimmia dry rock moss
1–2 cm, central strand absent.
1–1.5 cm.
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.
homomallous-falcate, oblong-lanceolate, from a clasping base tapering to a long, subulate uncinate point, 2–3.5 mm, margins plane, erect distally, intermarginal bands absent, usually muticous, occasionally short hyaline awns are present, not decurrent, costa narrow proximally;
basal juxtacostal laminal cells short-rectangular, straight to sinuose, thick-walled;
basal marginal laminal cells quadrate to short-rectangular, thick-walled;
medial laminal cells irregularly rounded to quadrate, sinuose, thick-walled;
distal laminal cells 2-stratose, irregularly rounded to quadrate.
straight, 2.5–3.5 mm.
dioicous, perichaetial leaves enlarged.
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.]
occasionally present, exserted, oblate, shiny, smooth, becoming striate when dry, stomata absent, annulus absent, operculum conical, peristome split in distal half, basal segments smooth, distal segments papillose.
unknown.
leaves not enlarged.
Grimmia reflexidens
Grimmia hamulosa
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.
Few collections of Grimmia hamulosa exist, its habitat is not well defined, and it is a somewhat confusing species. The original description is incomplete and partly incorrect, e.g. it lacks discussion and comparison with related taxa, and the seta is straight, not bent, as stated in the protologue. The species is characterized by: (1) a glossy habit with long tapering, homomallous, muticous leaves with plane margins; (2) a broad, weakly outlined costa that fills the distal part of the 2-stratose lamina; and (3) a glossy exserted capsule that lacks an annulus. Despite its unique leaf characters and lack of an annulus, Hastings has put it in subg. Litoneuron based on its thick, concave leaves with plane margins, costa not projecting prominently from the lamina, and exserted capsule on a straight seta. In 1999, Greven found G. hamulosa richly fruiting in Yosemite National Park. Although isotypes studied by Greven have muticous leaves, in some of the plants from Yosemite the leaves have inconspicuous short awns. However, these plants do not deviate in other aspects from the type specimen. Small specimens of this species resemble G. fragilis Schimper, a form of G. montana described from southern Europe. These plants are characterized by long, glossy leaves usually with broken tips. In G. hamulosa, the leaf tips are also frequently broken; however, in G. montana the costa is clearly defined, and the distal leaf margins are incurved.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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