Bryum argenteum
Bryum
silver bryum, silver-moss, silvergreen bryum moss, silvery thread moss
bryum moss
0.2–1 cm, strongly rounded julaceous or sometimes gemmiform.
0.2–1(–2) cm, weakly to strongly rounded julaceous or short-gemmiform, not or weakly branched;
rhizoids few or many, micronemata and macronemata absent from stems or present in clusters proximally.
erect when moist, ovate to ovate-lanceolate, somewhat concave, 0.3–1(–1.2) mm;
base green;
margins rarely recurved proximally or plane distally;
apex broadly rounded to acute, not cucullate, hyaline in distal 1/4–1/2 of leaf or rarely nearly entirely green;
costa not reaching apex, apiculus present, sometimes short or nearly absent, hyaline, irregularly incurved when dry;
proximal laminal cells quadrate or short-rectangular, 12–18 µm wide, 1–2:1;
distal cells short- or elongate-hexagonal, (30–)40–80 × 10–15 µm, (1–)3–5:1, walls thin or somewhat thickened, not distinctly incrassate.
with fertile stem leaves imbricate when dry, erect to erect-spreading when moist, ovate-lanceolate to ovate, concave, 0.2–1(–1.5) mm;
base not decurrent;
margins recurved proximally, plane distally, or often plane throughout, ± entire, 1-stratose, limbidium absent;
apex broadly rounded to acute or rarely acuminate;
costa not reaching apex or excurrent, apiculus sometimes present if costa not reaching apex, often hyaline, smooth, guide cells usually absent;
alar cells not or somewhat differentiated from juxtacostal cells, usually shorter;
laminal areolation distinctly heterogeneous;
proximal laminal cells quadrate or short-rectangular, 1–2(–3):1;
medial and distal cells short-rhomboidal to elongate-hexagonal or rarely vermicular, (1–)3–6(–8):1, walls thin to incrassate, not pitted.
brown to red-brown, 1–2 cm.
single, somewhat twisted when dry.
dioicous;
perigonia and perichaetia terminal, leaves same size as vegetative leaves or usually larger, not forming rosette, inner leaves not much differentiated.
red to red-brown, ovate, 2–3 mm;
hypophysis differentiated, somewhat thickened.
inclined to pendent, ovate or clavate to pyriform, (1–)2–3 mm;
hypophysis differentiated or not;
operculum weakly convex, short-conic, not rostrate;
peristome double;
exostome pale yellow or tan, teeth slender lanceolate;
endostome separate from exostome or sometimes adherent or absent, basal membrane low to high, segments present, perforate, cilia appendiculate or sometimes absent.
8–15 µm.
shed singly, not as tetrads, 8–15(–18) µm, finely papillose, pale tan or yellow-tan.
asexual reproduction by leaf axil bulbils, leafy, small.
asexual reproduction by leaf axil bulbils or absent.
Bryum argenteum
Bryum
Varieties ca. 30 (3 in the flora).
Bryum argenteum is perhaps the most widespread and distinctive moss in the world, although in many regions it is found primarily in urban or other heavily disturbed sites and is mostly absent from native undisturbed habitats in the tropics. There are about 15 silver-white species described, with species definitions based on a combination of one of three or four different basic gametophyte morphologies combined with subtle differences in the sporophytes. However, much of the gametophyte variability in the complex is also exhibited by B. argenteum itself, thus confusing species-level identifications. This complex is urgently in need of worldwide molecular and morphological studies.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 40 (7 in the flora).
Bryum in the strict sense is a genus of small julaceous plants, morphologically similar to Anomobryum. Molecular studies, however, consistently show that the types of the two genera, A. julaceum and B. argenteum, are not closely related. Anomobryum can generally be distinguished from Bryum by its vermicular distal laminal cells and elongate stringlike stems. Bryum species tend to have shorter laminal cells and relatively short, thick, rounded stems. Bryum consists of both silver-white species with hyaline leaf tips, and green to yellow-green species. Many collections of small sterile shoots are difficult to identify. There are at least three undescribed species in the flora area, two of which are discussed under related species. The third is highly distinctive and has been collected recently from southeastern Arizona. Bryum in the broad sense has a reputation for being taxonomically difficult; the genus is highly polyphyletic, and traditionally, many species have been distinguished by minor differences in peristome features. Previous classifications have overemphasized the peristome, placing taxa with strikingly different gametophytes in the same genus. The gametophytes of Bryum vary widely morphologically; this has been used as a basis to reclassify the genus and its relatives (J. R. Spence 2005; Spence and H. P. Ramsay 2005).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Stems loosely julaceous; plants green; leaves hyaline near apex; costal apiculus long. | var. majus |
1. Stems distinctly julaceous or gemmiform to short-julaceous; plants hoary white to silver-green; leaves hyaline in distal 1/4 -1/2; costal apiculus absent, short, or long | → 2 |
2. Stems 0.5-1 cm, julaceous; leaves longer than broad; distal laminal cells elongate, 3-4(-5):1; costal apiculus long. | var. argenteum |
2. Stems shorter than 0.2 cm, sometimes gemmiform; leaves often broader than long; distal laminal cells short, (1-)2-3:1; costal apiculus absent or very short. | var. muticum |
1. Plants silver-green or white; leaves hyaline distally, including apiculus or awn; distal laminal cells elongate-hexagonal (short-hexagonal in B. argenteum var. muticum), less than 16 µm wide | → 2 |
1. Plants yellow-green, golden, olive green, or bright green; leaves not hyaline distally, or apiculus if present sometimes hyaline; distal laminal cells elongate-vermicular to short-rhomboidal, occasionally hexagonal, 6-25 µm wide | → 3 |
2. Plants white-green to silver-green; stems strongly rounded julaceous or sometimes gemmiform; costae not reaching apex, apiculus present or sometimes absent, irregularly incurved when dry; specialized asexual reproduction by leaf axil bulbils. | B. argenteum |
2. Plants hoary white; stems evenly foliate, weakly julaceous; costae long-excurrent, awns slender, recurved when dry; specialized asexual reproduction absent. | B. lanatum |
3. Distal laminal cells of innovation leaves linear-vermicular to elongate-hexagonal, 6-10 (-12) µm wide; specialized asexual reproduction by leaf axil bulbils; leaf bases red. | B. blindii |
3. Distal laminal cells of innovation leaves not vermicular (except B. chryseum), usually 8-12 µm wide or more; specialized asexual reproduction absent; leaf bases red, green, or yellow-green | → 4 |
4. Plants golden yellow to yellow-green, rarely pale green; leaves triangular to ovate; costae long-excurrent, awns slender. | B. chryseum |
4. Plants yellow-green, olive green, or bright green; leaves ovate to suborbicular; costae not reaching apex or rarely percurrent, apiculus absent or short | → 5 |
5. Plants green to yellow-green; distal laminal cells of fertile stem leaves elongate- hexagonal, 4-5(-6):1; leaf bases red. | B. oblongum |
5. Plants olive green to bright green; distal laminal cells of fertile stem leaves irregularly rhomboidal to hexagonal, 1-4:1; leaf bases green | → 6 |
6. Leaf apices broadly rounded to acute, cucullate; costal apiculus often present, of more than 2 cells; distal laminal cells irregularly rhomboidal, 12-25 µm wide; proximal cells predominantly quadrate. | B. calobryoides |
6. Leaf apices acute, not cucullate; costal apiculus absent or of 1 or 2 cells; distal laminal cells hexagonal, 10-16 µm wide; proximal cells short- rectangular. | B. veronense |
BC
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
