Wilcox's panicgrass
Dichanthelium wilcoxianum (Vasey) Freckmann

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Wilcox’s panicgrass occurs in the north-central United States. In Iowa, this species is rare to frequent on dry, sandy or rocky upland prairies, well-drained pastures, mostly along the Missouri river, in the Loess bluffs, and in the lake region of northwestern Iowa. Like other species of Dichanthelium, Wilcox’s 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.

Dichantheliums normally produce a basal rosette of leaves that persists through the winter, remaining green. In Wilcox’s 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). Wilcox’s panicgrass is readily distinguished from the other linear-leaved dichantheliums, though, by its leaf blades being all more or less the same length and relatively slightly wider and ellipsoid spikelets 2.5-3 mm long lacking the beak characteristic of starved panicgrass (Dichanthelium depauperatum). Wilcox’s panicgrass also lacks the basal secondary flowering heads of long-stalked panicgrass (Dichanthelium perlongum).

Etymology: Dichanthelium from the Greek di = twice and anth = flowering, referring to the occurrence of two distinct flowering periods; wilcoxianum honors the botanist General Timothy E. Wilcox (1840-1932) of the U.S. Army, who in 1888 collected the type material for this species in Nebraska.

 

Plants perennial, tufted. Culms 10-30 (-35) cm, stiffly erect, all but the upper 2-4 internodes very short, branching mainly near the base, not becoming much branched above; nodes smooth or with weak, reflexed hairs. Fall phase developing early, forming erect branches from the lower or middle nodes, the blades slightly reduced. Basal rosettes poorly differentiated. Leaves along the culms with sheaths papillose-hairy; blades 4-8 cm long, 3-5 mm wide, all stiffly erect, narrow, flat, green to grayish green, papillose-hairy. Primary flowering heads terminal, shortly exserted, 2-4 cm long, open, ovoid. Spikelets 2.5-3 mm long, 1.2-1.2 mm wide, ellipsoid, often reddish throughout, short hairy; lower glume 0.7-1.2 mm, triangular; upper glume and lower lemma 2.2-2.6 mm long, equaling the shiny upper floret, not forming a beak. Chromosome number 2n = 18.

 

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