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Muhlenbergia asperifolia (Nees & Meyen ex Trin.) Parodi
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Family: Poaceae
Alkali muhly
 Linda Ann Vorobik and Annaliese Miller, Illustrators |
Paul M. Peterson Plants perennial; rhizomatous, not cespitose, occasionally stoloniferous. Culms 10-60(100) cm, decumbent-ascending, bases somewhat compressed-keeled; internodes glabrous, shiny below the nodes. Sheaths glabrous, margins hyaline; ligules 0.2-1 mm, firm, truncate, ciliate, without lateral lobes; blades 2-7(11) cm long, 1-2.8(4) mm wide, flat, occasionally conduplicate, smooth or scabridulous abaxially, scabridulous adaxially, margins and midveins not conspicuously thickened, greenish, apices acute, not sharp. Panicles 6-21 cm long, 4-16 cm wide, broadly ovoid, open; primary branches 3-12 cm, capillary, lower branches spreading 30-90° from the rachises, never appearing fascicled; pedicels 3-14 mm, longer than the spikelets. Spikelets 1.2-2.1 mm, occasionally with 2 or 3 florets. Glumes equal, 0.6-1.7 mm, purplish, scabridulous, particularly on the veins, 1-veined, apices acute; lemmas 1.2-2.1 mm, lanceolate to oblong-elliptic, somewhat plumbeous, glabrous, usually smooth, occasionally scabridulous near the apices, apices acute, unawned or mucronate, mucros to 0.3 mm; paleas 1.2-2.1 mm, lanceolate, glabrous, acute; anthers 1-1.3 mm, greenish-yellow to purplish at maturity. Caryopses 0.8-1 mm, fusiform, brownish. 2n = 20, 22, 28. Muhlenbergia asperifolia grows in moist, often alkaline meadows, playa margins, and sandy washes, on grassy slopes, and around seeps and hot springs, at elevations of 55-3000 m. Its geographic range includes northern Mexico. Muhlenbergia asperifolia is morphologically similar to the southeastern M. torreyana, but differs in having glabrous, weakly compressed culms and more widely divergent panicle branches. The caryopses of Muhlenbergia asperifolia are frequently infected by a smut, Tilletia asperifolia Ellis & Everhart, which produces a globose body filled with blackish-brown spores. The Morton Aboretum Perennial rhizome-bearing, sometimes runner-forming herb 10 cm - 1.2 m tall Leaves: having open, hairless sheaths with transparent margins, and 0.2 - 1 mm long, firm, flat-topped ligules lined with hairs on the margins. The blades are greenish, 2 - 11 cm long and 1 - 4 mm wide with pointed tips, flat or sometimes folded lengthwise, smooth or minutely rough beneath, minutely rough above. Inflorescence: terminal, spike-like and branched (panicle), open, 6 - 21 cm long, 4 - 16 cm wide, broad egg-shaped. The hair-like primary branches are 3 - 12 cm long with the lower branches spreading 30 to 90 degrees from the main axis. Fruit: a brownish, spindle-shaped caryopsis, 0.8 - 1 mm long. Culm: 10 cm - 1 m long, decumbent to ascending, bases compressed or folded longitudinally, internodes hairless and shiny just below the nodes. Spikelets: 1.2 - 2.1 mm long, borne on a stalk 3 - 14 cm long. Glumes: equal, purplish, 0.6 - 1.7 mm long, with a pointed tip and a single minutely rough vein. Florets: one (sometimes two or three) per spikelet, with greenish yellow to purplish anthers 1 - 1.3 mm long. Lemma: lead-colored 1.2 - 2.1 mm long, lance-shaped to oblong-elliptic, three-veined, hairless and usually smooth, sometimes minutely rough near the pointed tip, unawned or with an awn to 0.3 mm long. Palea: 1.2 - 2.1 mm long, lance-shaped with a pointed tip, two-veined, hairless. Similar species: Muhlenbergia asperifolia can be easily distinguished from other Muhlenbergia species in the Chicago Region. It has spreading inflorescences 4 - 16 cm across and awnless spikelets less than 2 mm long. Flowering: mid July to early October Habitat and ecology: Introduced from the western United States, this species is a weed of railroad ballast, waste soils, industrial areas, and along expressways. Occurence in the Chicago region: non-native Etymology: Muhlenbergia is named after American botanist, Gotthilf Henry Ernest Muhlenberg (1753-1815). Asperifolia means harsh-leaved.
Author: The Morton Arboretum |
