Didymodon rigidulus
Didymodon ferrugineus
rigid didymodon moss
rusty beard moss
leaves appressed-incurved to weakly spreading when dry, spreading or not and not keeled when moist, monomorphic, long-ligulate, ovate-lanceolate, elliptic-lanceolate or long-lanceolate, broadly channeled across leaf or occasionally somewhat channeled along costa, 0.8–1.7(–3) mm, base scarcely differentiated to ovate, margins recurved in proximal 1/4–3/4, entire, apex acute to subulate, occasionally fragile;
costa percurrent to excurrent as a long, thick, blunt subula, not much widened or tapering through the leaf, not strongly spurred, lacking a bulging adaxial pad of cells, adaxial costal cells quadrate, in (2–)3–4(–5) rows, guide cells in a single layer;
basal laminal cells weakly differentiated medially, rectangular, walls thin to evenly thickened, proximal maginal cells little differentiated;
distal laminal cells mostly 8–11 µm wide, 1:1, papillae absent or simple or occasionally 2-fid, lumens oval to rounded-quadrate, walls evenly thickened, moderately bulging on both sides or only abaxially, sometimes 2-stratose marginally or at apex of leaf, or throughout lamina.
leaves appressed to spreading when dry, strongly recurved and keeled when moist, monomorphic, ovate-triangular to ovate-lanceolate, adaxially grooved along costa, 0.8–2 mm, base scarcely differentiated in shape to ovate, margins nearly plane to recurved at mid leaf, usually entire, apex broadly acute, not fragile;
costa percurrent to short-excurrent, weakly tapering and not much wider at the base, pad of cells absent, adaxial costal cells elongate, 2–4 cells wide at mid leaf, guide cells in 1 layer;
basal laminal cells little differentiated, quadrate or very short-rectangular, walls thickened;
distal laminal cells 11–15 µm wide, 1:1, papillae usually present, simple, often large and sharp, 1–3 centered over lumens, lumens angular, walls irregularly thickened, convex on both sides, 1-stratose.
0.7–1.7 cm.
0.6–1.2 cm.
1–2 mm;
peristome teeth 32 or 16 cleft to base or rudimentary or occasionally absent, filamentous or long-triangular, straight or weakly twisted, to 740 µm. Spores 9–12 µm. Distal laminal KOH reaction yellow- or red-orange.
0.7–1.5 mm;
peristome teeth 16, linear, cleft to near base, nearly straight to twisted counterclockwise once, 275–600 µm. Spores 7–9 µm. Distal laminal KOH reaction red- or orange-brown.
asexual reproduction by axillary, ovate to elliptic, multicellular gemmae.
asexual reproduction specialized structures absent.
Didymodon rigidulus
Didymodon ferrugineus
Varieties 6 (5 in the flora).
Didymodon rigidulus in the broad sense, as emended by R. H. Zander (1981b) is polymorphic, with several varieties distinguished by fairly good correlations of combinations of characters. Specimens of intermediate morphology that are not clearly assignable to any one variety may be identified as D. rigidulus in the broad sense. Although some authors use the presence of axillary gemmae as diagnostic of the typical variety, other varieties, notably var. gracilis, may occasionally have them. Such gemmae are also found in other species, especially those of the D. vinealis complex. Didymodon vinealis may have 2-stratose distal laminal cells, and should be carefully distinguished.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The sporophyte of Didymodon ferrugineus is rare and similar to, but often smaller than, that of D. fallax. This species is easily mistaken for the western Triquetrella californica, which, however, is quickly distinguished by its triangular stem section, distal leaf margins sharply crenulate by projecting papillae (but not by projecting cell walls as in D. nigrescens), and distal medial laminal papillae tall, branching from the base, and centered over each lumen. It intergrades with D. fallax to some extent but is usually larger, with broader, ovate-lanceolate leaves that are commonly strongly reflexed (and therefore do not lie flat on a slide), and the papillae may be large and strongly evident. The leaf base is never abruptly ovate as it sometimes is in D. fallax. The peristome is very fragile and often appears missing.
The illegitimate name Tortula recurvifolia (Schimper) Austin has also been used for this species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Lamina 2-stratose in distal 1/2-3/4 | var. subulatus |
1. Lamina 1-stratose or 2-stratose only at the extreme leaf apex or on the distal margins | → 2 |
2. Leaves oblong-lanceolate, elliptic-lanceolate or occasionally long-triangular; costa usually short-excurrent and blunt; apex and distal margins generally 2-stratose; gemmae often present | var. rigidulus |
2. Leaves short-lanceolate to lanceolate; costa percurrent to long-excurrent, usually sharp; distal margins 1-stratose or less commonly 2-stratose in patches; gemmae usually absent | → 3 |
3. Plants flagellate, leaves strongly appressed when dry, linear-lanceolate; costa long-excurrent | var. ditrichoides |
3. Plants thickly leaved, leaves appressed to spreading when dry, short-lanceolate to long-lanceolate; costa percurrent to long-excurrent | → 4 |
4. Leaves short- to long-lanceolate; base evenly broadened, square or rectangular; costa usually percurrent to short-excurrent as a rigid subula, seldom-excurrent; distal cells generally papillose, oval or rounded-quadrate; proximal cells short-rectangular; gemmae occasionally present | var. gracilis |
4. Leaves long-lanceolate; base abruptly broadened, ovate; costa usually long-excurrent as a straight or flexuose, often fragile subula; distal cells usually smooth, usually angular; proximal cells usually quadrate; gemmae very rare | var. icmadophilus |
WildflowerSearch
iNaturalist
USDA Plants Database
BC
IL Wildflowers
MI Flora
PNW Herbaria
