This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Panicum condensum Nash, in Small, Fl. SE. U. S. 93. 1903.
Culms 2 1/2°-4 1/2° tall; sheaths smooth and glabrous; ligule 1/2" wide; blades 8'-2o' long, 4"-6" wide, flat or folded; primary panicle up to 1° long, narrowly oblong, the branches erect, the spikelets densely arranged, the lower branches naked at the base, the secondary panicles similar but smaller and produced on long peduncles from the upper sheaths; spikelets about 1"- 1 1/4" long, glabrous, acute, on glabrous short pedicels.
Wet places and along streams, southern New Jersey and Pennsylvania to Virginia and Florida; also in the Bahamas, Cuba and Guadeloupe. Aug. and Sept.
Panicum longifolium Torr. Fl. U. S. 149. 1824.
Culms erect, 1°-2° tall, slender, simple, or occasionally with a single lateral panicle, flattened, smooth and glabrous. Sheaths smooth and glabrous; blades 8-12' long, 1"-2 1/2" wide, acuminate into a long, slender point, rough, glabrous; ligule short, pilose; panicles 5'-9' long; primary branches long and slender, spreading, secondary very short, appressed, generally bearing 1-3 spikelets; spikelets 1"-1 1/4" long, acute; first scale acute, about one-half as long as the acuminate second one; third scale equalling the second, acute, one-third longer than the elliptic obtuse fourth one, which is sometimes minutely pubescent at the apex.
Moist soil, Rhode Island to Maryland, Florida, Mississippi and Texas. Aug.-Sept.
Culms erect, 3°-5° tall, much branched, stout, compressed, smooth. Sheaths smooth and glabrous, compressed; blades 1° long or more, 2 "-4" wide, acuminate, scabrous; panicles pyramidal, terminating the culm and branches, 4'-12' long; primary branches spreading or ascending, the secondary appressed or divaricate; spikelets about 1 1/4" long, crowded, acuminate; first scale acute or acuminate, one-third the length of the equal or nearly equal second and third; fourth scale narrowly elliptic, about one-half as long as the third and raised on a delicate stalk about 1/4" long.
Moist soil, southern New York and New Jersey to Kentucky, Missouri, Georgia and Louisiana. July-Sept.
Panicum strictum Pursh, Fl. Am. Sept. 69. 1814. Noi R. Br. 1812.
Panicum depauperatum Muhl. Gram. 112. 1817.
Panicum involution Torr. Fl. U. S. 124. 1824.
Culms erect, 15' tall or less, simple or branched at base. Sheaths glabrous or hirsute; blades erect, elongated, V-2" wide, up to 8' long, mostly crowded at base and equalling or one-half as long as the culm, the upper culm leaf often much exceeding the panicle; primary panicle generally much exserted from the upper sheath, i'-3' long, elliptic to linear, its branches ascending or erect; secondary panicles on very short basal branches and often concealed by the lower leaves; spikelets glabrous, 1 3/4"-2" long.
In dry places, Maine to Minnesota, south to Georgia and Texas. June-Sept.