Paspalum setaceum var. muhlenbergii

Plants mostly erect. Leaves mostly cauline; blades to 25 cm long, 2-10.2 mm wide, lax to straight, surfaces and margins evenly hirsute, hairs 1.5-5.5 mm, light to dark green. Panicle branches 1.9-14.3 cm; branch axes 0.5-1 mm wide. Spikelets 1.8-2.5 mm long, 1.5-2 mm wide, oval to suborbicular, glabrous or with a few hairs, light green to green; lower lemmas usually with an evident midvein; upper florets 1.8-2.3 mm.

Paspalum setaceum var. muhlenbergii is endemic to the Flora region, extending from southern Ontario to the Gulf coast of Texas and northern Florida. It grows in disturbed areas and on the margins of forests. It resembles var. supinum, differing in its erect habit and, usually, in its spikelet shape and presence of a midvein on the lower lemma.

Perennial herb with short rhizomes or forming tufts 25 cm - 1 m tall Leaves: mostly consisting of stem leaves, alternate, two-ranked. Sheaths open, sometimes hairy. Ligules to 0.5 mm long, membranous. Blades straight to lax, to 25 cm long, 2 - 10 mm wide, lance-shaped, flat, parallel-veined, hairy (hairs 1.5 - 5.5 mm long). Inflorescence: a branched arrangement of spikelets (panicle), terminal and axillary, bearing one to six spike-like branches. Axillary panicles completely or partially enclosed by a subtending leaf sheath. Branches ascending to spreading, often bowed, 2 - 14.5 cm long, with spikelets mostly arranged in two rows along one side of the branch. Branch axes 0.5 - 1 mm wide, sometimes rough. Fruit: a caryopsis, indehiscent, enclosed within the persistent lemma and palea, white, elliptic to nearly orbicular. Culm: mostly upright, 25 cm - 1 m long, round in cross-section, hollow. Nodes sometimes hairy. Spikelets: paired, overlapping, arranged along one side of the inflorescence branch, appressed to the branch axis, bearing two florets, light green or green, 2 - 2.5 mm long, 1.5 - 2 mm wide, plano-convex (one side flat, the other convex), nearly orbicular to oval, sometimes with a few hairs. Glumes:: Lower glumes absent. Upper glumes nearly equal to lower lemmas, rounded at the apex, three-veined, sometimes shortly glandular-hairy, membranous. Lemmas:: Lower lemmas nearly equal to upper glumes, rounded at the apex, sometimes shortly glandular-hairy, membranous, three-veined, with an evident midvein. Upper lemmas clasping the paleas, straw-colored to brown, convex, smooth to slightly wrinkled, with rolled-up margins on the upper surface. Paleas:: Lower paleas rudimentary or absent. Upper paleas straw-colored to brown, smooth to slightly wrinkled. Florets:: Lower florets sterile. Upper florets bisexual, straw-colored, about 2 mm long. Anthers three. Stigmas red.

Similar species: No information at this time.

Flowering: June to September

Habitat and ecology: Disturbed and often sandy areas.

Occurence in the Chicago region: native

Etymology: Paspalum comes from the Greek word paspalos, a type of millet. Setaceum means bristle-like. Muehlenbergii is named in honor of Gotthilf Henry Ernest Muhlenberg (1753-1815), an American botanist.

Author: The Morton Arboretum