Muhlenbergia fragilis
Muhlenbergia frondosa
annual muhly, delicate muhly
common satin grass, leafy satin grass, muhlenbergie feuillée, wire-stem muhly
10-38 cm, erect or spreading;
internodes mostly glabrous, smooth or scabridulous, scabrous or strigulose below the nodes.
50-110 cm tall, 0.7-1.8 mm thick, ascending, geniculate, or decumbent, bushy and much branched above;
internodes smooth and shiny for most of their length, glabrous throughout.
often longer than the internodes, scabridulous, margins hyaline;
ligules 1-3 mm, hyaline, obtuse, irregularly toothed to lacerate, with lateral lobes;
blades 1-10 cm long, 0.4-2 mm wide, flat, scabrous abaxially, strigulose adaxially, margins and midveins thickened basally, whitish.
glabrous, margins hyaline;
ligules 0.7-1.7 mm, membranous, truncate, lacerate-ciliolate;
blades 4-18 cm long, 2-7 mm wide, flat, glabrous, smooth or scabridulous, those of the lateral branches similar to those of the primary culms.
10-24 cm long, 3.5-11 cm wide, diffuse;
primary branches 2.2-6.2 cm long, about 0.1 mm thick, diverging 80-100° from the rachises, straight;
pedicels 6-10 mm long, about 0.02 mm thick, delicate;
disarticulation above the glumes.
2-15 cm long, 0.3-2 cm wide, sometimes dense;
axillary panicles common, partly included in the sheaths;
primary branches 0.3-4.2 cm, ascending, appressed, occasionally diverging up to 30° from the rachises;
pedicels 0.4-5 mm, smooth or scabrous.
1-1.2 mm, appressed to slightly divergent.
2.2-4 mm, imbricate along the branches.
equal to subequal, 0.5-1 mm, glabrous throughout or obscurely puberulent, hairs about 0.06 mm, 1-veined, obtuse or subacute;
lemmas 1-1.2 mm, oblong-elliptic, purplish to light brownish, not mottled, glabrous or densely appressed-puberulent on the margins and midveins, apices obtuse, unawned;
paleas 0.9-1.2 mm, oblong-elliptic;
anthers 0.3-0.5 mm, purplish.
subequal, 2-4 mm, 3/4 as long as to longer than the lemmas, 1-veined, unawned or awned, awns to 2 mm;
upper glumes acuminate to acute;
lemmas 2.2-4 mm, narrowly lanceolate, hairy on the calluses, lower 1/3 of the midveins, and margins, hairs 0.3-0.8 mm, apices scabridulous, acuminate, unawned or awned, awns 0.1-13 mm;
paleas 2.3-4 mm, narrowly lanceolate, acuminate;
anthers 0.3-0.6 mm, usually yellow, occasionally purplish.
0.7-0.9 mm, elliptic, reddish-brown.
1.6-1.9 mm, fusiform, brown.
= 20.
= 40.
Muhlenbergia fragilis
Muhlenbergia frondosa
Muhlenbergia fragilis grows on rocky talus slopes, cliffs, canyon walls, road cuts, and sandy slopes, often over calcareous parent materials, at elevations of 480-2200 m. It is usually found in oak-gramma savannahs, thorn scrub forests, oak-yellow pine forests, and pinyon-juniper woodlands. Its range extends from the southwestern United States to southern Mexico.
Populations may have individual plants with completely glabrous lemmas or may consist entirely of such plants. This morphological variation is not correlated with any distributional or habitat characteristics.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Muhlenbergia frondosa grows in forest borders, thickets, clearings, alluvial plains, and disturbed sites within deciduous forests, at elevations of 20-1000 m. It grows only in southern Canada and the contiguous United States. The collection from Oregon was made in an artificial cranberry bog and was probably introduced with the plants.
Plants with unawned or shortly (less than 4 mm) awned lemmas can be called M. frondosa forma frondosa, and those with lemma awns 4-13 mm long, M. frondosa forma commutata (Scribn.) Fernald.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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