Publication: Flora Boreali-Americana 1: 51, pl. 9. 1803.
selected vouchers: WTU
Notes: FNA24: "Panicum capillare subsp. capillare is the common subspecies, growing in weedy and dry habitats throughout the range of the species. Plants in the western United States and Canada have spikelets over 2.6 mm long more often than those in the east. Robust plants germinating early in the season and growing on better soils tend to spread more, and have wider, shorter blades and more exserted panicles than plants in the eastern United States and Canada growing under comparable conditions. They are sometimes included in P. capillare var. occidentale Rydb., but these traits are not well correlated, and several environmental factors apparently affect their expression. Plants in the eastern part of the range with a well-exserted main panicle at anthesis usually arise from seeds germinating relatively late in the season."
KZ99 (citing the 1996 Annals of the Missouri Botanical Garden) reports Panicum hirticaule J. Presl var. hirticaule from WA, but it is not found in the Pacific Northwest acording to FNA.