Paspalum setaceum var. psammophilum

Plants spreading to prostrate. Leaves mostly cauline; blades to 16 cm long, 2.8-8.3 mm wide, lax to straight, grayish-green, surfaces and margins evidently hirsute, with soft, short hairs. Panicle branches 3.1-5.9 cm; branch axes 0.7-1 mm wide. Spikelets 1.8-2.2 mm long, 1.6-1.8 mm wide, suborbicular to orbicular, pubescent; lower lemmas without an evident midvein; upper florets 1.8-2.1 mm.

Paspalum setaceum var. psammophilum grows in sandy, maritime habitats and, inland, along sandy roadsides and in dry fields, from Massachusetts to the District of Columbia. The combination of its spreading to prostrate habit and densely puberulent foliage distinguishes it from other varieties of P. setaceum.

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, grayish green, to 16 cm long, 3 - 8.5 mm wide, lance-shaped, flat, parallel-veined, softly short-hairy. 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, 3 - 6 cm long, with spikelets mostly arranged in two rows along one side of the branch. Branch axes 0.7 - 1 mm wide, sometimes rough. Fruit: a caryopsis, indehiscent, enclosed within the persistent lemma and palea, white, elliptic to nearly orbicular. Culm: prostrate or spreading, 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, straw-colored or brown, 1.5 - 2 mm long, 1.5 - 2 mm wide, plano-convex (one side flat, the other convex), more or less orbicular, and hairy. 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, three-veined, sometimes shortly glandular-hairy, membranous. 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: Sandy areas.

Occurence in the Chicago region: native

Etymology: Paspalum comes from the Greek word paspalos, a type of millet. Setaceum means bristle-like. Psammophilum means sand-lover.

Author: The Morton Arboretum