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Dichanthelium acuminatum subsp. fasciculatum (Torr.) Freckmann & Lelong (redirected from: Panicum lassenianum)
Family: Poaceae
western panicgrass
[Dichanthelium acuminatum var. fasciculatum (Torr.) Freckmann,  more]
Dichanthelium acuminatum subsp. fasciculatum image

Panic Laineux

Plants yellowish-green to olivaceous or purplish. Culms 15-75 cm, suberect, ascending or spreading; nodes often with spreading hairs, occasionally with a glabrous ring below. Cauline sheaths with ascending to spreading, papillose-based hairs, occasionally with shorter hairs underneath; midculm sheaths about 1/2 as long as the internodes; blades 5-12 cm long, 6-12 mm wide, spreading to ascending, bases with papillose-based cilia, abaxial surfaces usually pubescent, adaxial surfaces pilose or glabrous, hairs shorter than 3 mm. Spikelets 1.5-2 mm (tending to be longer in the western part of its range), obovoid to ellipsoid.

Dichanthelium acuminatum subsp. fasciculatum grows primarily in disturbed areas, open or cut-over woods, thickets, and grasslands, in dry to moist soils, including river banks, lake margins, and marshy areas. It is widespread in temperate North America, growing from Canada to Mexico, but it is somewhat less common in the western part of its range, where it often occurs on moister areas.

Dichanthelium acuminatum subsp. fasciculatum includes probably the most widespread, ubiquitous, and variable assemblages of forms in the species. It is not always clearly separable from the other subspecies of D. acuminatum, especially subsp. acuminatum, subsp. implicatum, and subsp. lindheimeri. Gene exchange with other Dichanthelium species (including D. dichotomum, D. laxiflorum, D. ovale, D. commutatum, and D. boreale) probably occurs not infrequently.

Perennial herb, tufted 15 cm - 0.75 m tall Inflorescence: a terminal, branched arrangement of spikelets (panicle). Primary panicles atop the culms, often open, rather dense, 3 - 12 cm long, one-fourth to three-fourths as wide as long, well-exserted. Secondary panicles (when present) atop the branches. Fruit: a caryopsis, indehiscent, enclosed within the persistent lemma and palea. Culm: nearly upright or ascending or spreading, 15 cm - 0.75 m long, round in cross-section, hollow. Nodes sometimes swollen, often with spreading hairs and occasionally a hairless ring below. Spikelets: 1.5 - 2 mm long, ellipsoid or reverse egg-shaped with a blunt to nearly pointed apex, variously hairy. Basal leaves: in a rosette. Blades shortly egg-shaped to lance-shaped, distinct from stem blades. Stem leaves: four to seven, alternate, two-ranked. Sheaths usually shorter than internodes (about half as long at mid-culm), with bumpy-based hairs. Ligules and pseudoligules 1 - 5 mm long, composed of hairs. Blades lax or firm, spreading to ascending, distinctly longer and narrower than basal leaves, 5 - 12 cm long, 6 - 12 mm wide, lance-shaped with a rounded or almost heart-shaped base, parallel-veined, hairy beneath, sometimes softly hairy above, (hairs under 3 mm long), with a marginal fringe of bumpy-based hairs basally. Glumes:: Lower glumes usually one-fourth to one-half as long as spikelets, blunt to pointed at the apex. Upper glumes rounded to pointed at the apex. Lemmas:: Lower lemmas similar to upper glumes. Upper lemmas longitudinally lined, shiny, with rolled-up margins above. Paleas:: Lower paleas shorter than lower lemmas, thin. Upper paleas longitudinally lined. Florets:: Lower florets sterile. Upper florets bisexual, stalkless, 1 - 1.5 mm long, 0.5 - 1 mm wide, ellipsoid with a blunt to pointed apex, plump. Anthers three. Stigmas red.

Similar species: No information at this time.

Habitat and ecology: Rare in the Chicago Region, and known only from Lake County, Indiana. It is found in sandy areas.

Occurence in the Chicago region: native

Etymology: Dichanthelium comes from the Greek words di, meaning twice, and anth, meaning flowering, referring to plants that may have two flowering periods. Acuminatum means "tapering to a long point." Fasciculatum means bundled or banded.

Author: The Morton Arboretum