Syn. Musc. Eur. ed. 2,.

Etymology: Greek gyrus, circle, and genus Weissia, alluding to resemblance and well-developed, persistent annulus
Treatment appears in FNA Volume 27. Treatment on page 523. Mentioned on page 479, 524, 535, 642.

Plants gregarious or forming a thin turf, green distally, tan proximally. Stems to 0.4[–3] cm, branching occasionally; rounded-pentagonal in transverse section, hyalodermis absent, sclerodermis present as substereids, central strand present or absent; rhizoids few; axillary hairs of ca. 5(–10) cells, the basal 1–2 brownish. Leaves appressed-incurved when dry, weakly spreading reflexed when moist; narrowly ligulate or rectangular to long-ovate, adaxial surface nearly flat, 0.25–1.4 mm; base scarcely differentiated to ovate [sheathing]; distal margins plane to weakly recurved, entire, 1-stratose [2-stratose]; apex rounded to rounded acute or obtuse, sometimes apiculate by a sharp cell; costa ending ca. 4[–8] cells below apex [percurrent], adaxial outgrowths absent, adaxial cells elongate in 2–8 rows, abaxial cells elongate; transverse section of costa semicircular to ovate, adaxial epidermis usually present, adaxial stereid band absent or weak, exposed, guide cells 2 in 1 layer, hydroid strand absent, abaxial stereid band present, crescentiform or round in sectional shape, abaxial epidermis present or commonly absent; basal cells differentiated across leaf base in proximal 1/4–1/2 of leaf, little wider than distal cells or somewhat bulging [inflated], 3–5:1, walls of basal cells thin to evenly thickened; distal medial cells quadrate or shortly rectangular, ca. 8–11 µm wide, 1(–2):1, papillae absent or hollow, simple to indistinctly 2-fid, cell walls thin to evenly thickened, superficially flat to convex. Specialized asexual reproduction when present by oval to spindle-shaped gemmae, of several cells, borne on basal rhizoids, green or brown. Sexual condition dioicous [autoicous, occasionally heteroicous]; perigonia appear as buds at plant base or terminal, gemmate; perichaetia terminal, inner leaves often strongly sheathing seta, lanceolate, to 1.5 mm, laminal cells often rectangular to rhomboid. Seta yellow-brown, ca. 1.5–3[–6] mm, twisted clockwise. Capsule yellow-brown, ovate to short-cylindric, [neck differentiated,] 0.8–1 mm, exothecial cells shortly rectangular to rhomboid, thin-walled, annulus of 2–3 rows of highly vesiculose cells, revoluble and deciduous in pieces; operculum short-conic [narrowly rostrate], ca. 0.2–0.3[–0.6] mm, cells in straight rows; peristome teeth absent [16, rudimentary, short, spreading, ligulate or oblong and highly perforate, straight, articulations ca. 3–4, ca. 30–80 µm, lightly papillose to closely spiculose, basal membrane low]. Calyptra cucullate, ca. 0.7–1[–1.4] mm, smooth. Spores ca. 9–11 µm, smooth to papillose, light brown. KOH laminal color reaction yellow, rarely orange.


North America, Europe, Asia (China, Middle East), Africa.


Species 6 (1 in the flora).

Gyroweisia species have ligulate leaves with subpercurrent costae and enlarged, hyaline basal cells, a vesiculose annulus, and peristome absent or rudimentary peristome. Gyroweisia differs from the similar Gymnostomum by the occasional presence of a rudimentary peristome (outside the flora area), the large annulus, sterile plants distinctly smaller than the sporophyte-bearing gametophytes, basal leaf cells differentiated more strongly (often in the basal 1/4 to 1/2), and the more common presence of gemmae.

Excluded Species:

Gyroweisia pusilla (Kindberg) Brotherus

This entity was treated as a synonym of Gymnostomum calcareum by A. L. Andrews (1922b).

Gyroweisia reflexa (Bridel) Schimper

This is a peristomate species known for the flora area previously only from a single collection in Grey County, Owen Sound, Ontario (Moxley s.n., May 1924, CANM). The specimen is indeed that, but H. A. Crum and L. E. Anderson (1981) questioned the report, suggesting a confusion of specimens by Moxley (as reviewed by W. R. Manierre 1998). The region of the original station, now built over, has been examined by others, but no additional sites discovered. The Michigan collection (MO) reported by Manierre is Tortula obtusifolia (Schwägrichen) Mathieu, which, though similar in the ligulate leaves and rudimentary peristome, differs significantly in the crowded, short-ovate leaves, and the single stereid band and enlarged adaxial superficial cells of the costa in section. Although it would be difficult to demonstrate the absence of this species, given the circumstances it is now appropriate to consider it absent from the New World.

Lower Taxa

... more about "Gyroweisia"
Richard H. Zander +
Schimper +
Pottiaceae tribe Barbuleae +
North America +, Europe +, Asia (China +, Middle East) +  and Africa. +
Greek gyrus, circle, and genus Weissia, alluding to resemblance and well-developed, persistent annulus +
Syn. Musc. Eur. ed. +
andrews1922a +, conard1945a +, manierre1998a +, mogensen1999a +  and steere1939a +
Gyroweisia +
Pottiaceae subfam. Barbuloideae +