Vascular Plants of North Carolina
Account for Blunt Switchgrass - Panicum virgatum var. cubense   Grisebach
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DistributionCoastal Plain, Sandhills, and lower Piedmont. Scattered records at low elevations in the Mountains.

Mostly Coastal Plain, southeastern MA to southern FL and southeastern LA; Cuba.
AbundanceFrequent to common in the Coastal Plain and Sandhills, uncommon to rare in the Piedmont and Mountains. The var. cubense is the "switchgrass" that most biologists encounter in +- natural habitats. Taller and denser-flowered plants of roadsides and disturbed areas have been planted and locally escaped; they are var. virgatum.
HabitatSeasonally wet or inundated depressions, shores of sinkhole ponds, blackwater streamhead ecotones, wet pine savannas and flatwoods; montane seepage bogs and serpentine barrens (Clay Co.).
PhenologyFlowering and fruiting late June-October.
IdentificationDue to unfortunate past lumping by authors, most NC botanists do not realize that var. cubense is the form of switchgrass most often encountered in the state. The nominate var. virgatum is native only locally and has been planted widely on roadsides and even in "native grassland" restoration sites. Variety spissum is maritime only. From both of them, var. cubense is told by its shorter spikelets (2.8-3.5 mm long vs. 3.2-5) and beak of sterile lemma exceeds the fertile lemma by 0.2-0.5 mm (vs. 0.6-1.3). Once learned, it is seen in the field as a smaller, almost delicate version of the other varieties.
Taxonomic CommentsIn the past, unnecessary lumping of this variety (or species?) has led to confusion of switchgrasses in NC.

The genus Panicum in the broad sense was once very large, but with the split of Dichanthelium in the 1980s, it has been reduced to manageable size. In more recent decades, other genera have been split off: Coleataenia, Hymenachne, Kellochloa, and Phanopyrum, as examples. All 6 of these genera can be readily told from each other in the field with just a hand lens. For a more detailed discussion, see the introductory paragraphs in Weakley (2018).
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