Grimmia reflexidens
Grimmia shastae
1–2 cm, central strand absent.
0.3–1 cm.
clusters of globular, brown, multicellular gemmae abundantly present on the adaxial side of the distal lamina.
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.
ovate to broadly oblong-lanceolate, 1–1.5 × 0.5–0.6 mm, larger towards stem tips, not keeled, frequently plicate in extreme apex, margins plane, incurved distally, long-awned, decurrent, costa weak proximally, broadened and deeply channeled distally;
basal juxtacostal laminal cells rectangular, straight, with thin walls;
basal marginal laminal cells rectangular, with thick transverse walls and thin lateral walls, hyaline in 3–4 rows;
medial laminal cells short-rectangular, sinuose, slightly thick-walled;
distal laminal cells 1-stratose with 2-stratose ridges, in apex entirely 2-stratose.
dioicous, perichaetial leaves enlarged.
probably dioicous, gametangia not seen.
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.]
unknown.
Grimmia reflexidens
Grimmia shastae
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 shastae is known only from Mt. Shasta. Its discovery demonstrates that the bryoflora of California is still not fully known. It also shows that the state is exceptionally rich in endemic species of Grimmia: G. mariniana, G. nevadensis, G. serrana, and G. shastae. Because of its abundantly present gemmae on the adaxial surface of the distal lamina, the latter is not likely to be confused with any other species of the genus. While gemmae are not rare in Grimmia, they are usually produced on leaf tips (G. anomala, G. hartmanii), on the abaxial side of the leaf (G. torquata, G. trichophylla), or in leaf axils (G. trichophylla, G. muehlenbeckii). In no other Grimmia species are gemmae produced in clusters on the surface of the adaxial lamina at the distal part of the leaf. The position of the species within the genus is not clear. Although its leaf form and areolation demonstrate its similarity to G. tergestina (subg. Litoneuron), the longitudinal plicae in the most distal leaves align it with G. caespiticia (subg. Guembelia). Sinuose laminal cell walls, characteristic of Grimmia, are only weakly present.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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