linear-leaved panicgrass (slim-leaved panicgrass, rosette panicgrass)
Dichanthelium linearifolium (Scribner) Gould

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Linear-leaved panicgrass is fairly widespread in the central and northeastern United States. In Iowa, it is relatively uncommon in northwestern and central Iowa. It occurs on dry, sandy, and gravelly prairies and open woodlands in eastern to south-central Iowa. Like other species of Dichanthelium, linear-leaved panicgrass is characterized by two distinct blooming periods. The conspicuous primary flowering heads are terminal to the culms and are produced from May into June, early in the season. Later on, usually from late June through July (and rarely later), the plants branch profusely to produce small secondary flowering heads in the basal leaf axils. The primary flowering heads usually have a lower seed set than the secondary ones, which have flowers that remain closed and are self-pollinated. Fruiting begins in mid-June, and spikelets begin dropping in mid-July.

Dichantheliums normally produce a basal rosette of leaves that remains green and persists through the winter. In linear-leaved panicgrass and the other three species that it is most closely related to, the basal rosette is usually only poorly developed. In addition, these four species share narrow leaf blades (usually at least 20 times longer than wide). Linear-leaved panicgrass is distinguished from the other narrow-leaved dichantheliums, though, by having leaves that are in-rolled near the base and wider above, smooth flowering stalks, and spikelets with prominent veins on the lower bracts. Its spikelets are smaller than those of starved panicgrass and they also lack a beak. This species forms occasional hybrids with starved panicgrass (Dichanthelium depauperatum) and long-stalked panicgrass (Dichanthelium perlongum).

Etymology: Dichanthelium from the Greek di = twice and anth = flowering, referring to the occurrence of two distinct flowering periods; linearifolium from the Latin linearis = and folius = leaved, referring to the linear leaves.

 

Plants perennial, tufted. Culms 15-50 cm, erect to drooping, the lower several internodes telescoped together, less than 2 cm long, the upper two internodes elongated; bearing most leaves and branches near the base; nodes hairy. Fall phase developing a dense mass of erect blades and shortened branches from the basal nodes. Basal rosettes poorly differentiated. Leaves along the culms with sheaths smooth to densely finely papillose-hairy; blades 5-25 cm long, 2-4 mm wide, long-tapered, green to grayish green, smooth to densely hairy, the lower blades shorter than the upper 2 or 3, stiffly ascending to erect. Primary flowering heads terminal, long-exserted, 3-8 cm long, 0.5-4 cm wide, slender to pyramidal. Spikelets 2.4-3.1 mm long, 1.1-1.7 mm wide, ellipsoid, smooth to sparsely short-hairy; lower glume 0.6-1.1 mm, ovate-triangular; upper glume and lower lemma 2.3-3 mm long, exceeding the shiny upper floret by about 0.2 mm before flowering but not forming a beak. Chromosome number 2n = 18.

 

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