Plants perennial; synoecious; rhizomatous, rhizomes short or elongate. Culms 50-250 cm, solitary or few. Leaves cauline; sheaths open; ligules of hairs, dense, short; blades elongate, long tapering. Inflorescences terminal, simple panicles, usually exserted and exceeding the upper leaves, open to contracted; panicles 8-80 cm long, to 60 cm wide, simple, flexible, branches not spikelike, not disarticulating. Spikelets with 1 floret, laterally compressed, unawned; rachillas not prolonged; disarticulation above the glumes, achenes falling with the lemmas and paleas. Glumes subequal to unequal, 1-veined, acute; calluses evidently hairy, hairs 1/4-7/8 as long as the lemmas; lemmas similar to the glumes, from shorter than to longer than the upper glumes, 1-veined, acute, unawned; paleas longitudinally grooved; anthers 3, 2.4-5.5 mm; ovaries glabrous. Fruit an achene, pericarp free from the seed. x = 10. Name from the Greek kalamos, reed, and Vilfa, a genus of grasses.

Calamovilfa is a genus of five species, all of which are endemic to temperate portions of the Flora region.

1.   Calamovilfa gigantea (Nutt.) Scribn. & Merr.
Giant Sandreed

Rhizomes elongate, covered with shiny, coriaceous, scalelike leaves. Culms to 2.5 m. Sheaths entirely glabrous or pubescent at the throat; ligules 0.7-2 mm; blades to 90 cm long, about 12 mm wide. Panicles 20-80 cm long, 20-60 cm wide; branches to 35 cm, ascending to strongly divergent, lowermost branches sometimes reflexed. Spikelets 7-10.8 mm. Glumes straight; lower glumes 4.5-10.5 mm; upper glumes 6.4-10.1 mm; callus hairs 1/4-3/4 as long as the lemma; lemmas 6-10 mm, straight, pubescent, sometimes sparsely so, very rarely glabrous; paleas 6-8.3 mm, pubescent or glabrous; anthers 3-5.5 mm. 2n = 60.

Calamovilfa gigantea grows on sand dunes, prairies, river banks, and flood plains in the Rocky Mountains and central plains from Utah and Nebraska to Arizona and Texas.

2.   Calamovilfa longifolia (Hook.) Scribn.
Prairie Sandreed

Rhizomes elongate, covered with shiny, coriaceous, scalelike leaves. Culms to 2.4 m. Sheaths glabrous or sparsely to densely pubescent; ligules 0.7-2.5 mm; blades to 64 cm long, about 12 mm wide. Panicles 15-78 cm long, 1.7-26.4 cm wide; branches to 33 cm, erect to strongly divergent, lowermost branches sometimes reflexed. Spikelets 5-8.5 mm. Glumes straight; lower glumes 3.5-6.5 mm; upper glumes 5-8.2 mm; lemmas 4.5-7.1 mm, straight, glabrous; paleas 4.4-6.9 mm, glabrous. 2n = 40, ca. 60.

Calamovilfa longifolia usually grows in sand or sandy soils, but is occasionally found in clay soils or loess. Two geographically contiguous varieties exist. They differ as shown in the following key; the differences between the two are more striking in the field.

Calamovilfa longifolia (Hook.) Scribn. var. longifolia

Sheaths usually glabrous, sometimes sparsely pubescent, rarely densely pubescent. Panicles to 55.5 cm long, usually 6.7-13.9 times as long as wide; branches to 23 cm long, erect or ascending, at least in the upper 1/3 of the panicle. Spikelets usually without a brownish cast, relatively closely imbricate.

Calamovilfa longifolia var. longifolia is a characteristic grass on the drier prairies of the interior plains, from southern Canada to northern New Mexico, with reports from southern Arizona. It also grows, as an adventive, in Washington, Wisconsin, Michigan, and Missouri.

Calamovilfa longifolia var. magna Scribn. & Merr.

Sheaths usually pubescent, often densely so, rarely glabrous. Panicles to 77.5 cm long, usually 1.3-5.5 times as long as wide; branches to 33 cm long, typically widely divergent, sometimes reflexed in the lower 1/3 of the panicle. Spikelets commonly with a brownish cast, relatively loosely imbricate.

Calamovilfa longifolia var. magna grows on dunes and sandy shores around lakes Superior, Michigan and Huron, with outlying stations in sand or sandy soils.

3.   Calamovilfa curtissii (Vasey) Scribn.
Florida Sandreed

Rhizomes short, covered with the persistent bases of the foliage leaves. Culms to 2 m. Sheaths to 30 cm; ligules to 0.5 mm; blades to 50 cm long, 2-5 mm wide. Panicles to 50 cm long, about 3.5 cm wide, contracted; branches to 20 cm, erect. Spikelets 3.5-5.4 mm. Glumesstraight; lower glumes 2-4.7 mm; upper glumes 3.5-5.4 mm; callus hairs 1/4-1/2 as long as the lemmas; lemmas 3.5-5.2 mm, straight, lightly to markedly pubescent; paleas 3.5-5 mm, slightly to markedly pubescent; anthers 2.5-3.1 mm. 2n = unknown.

Calamovilfa curtissii is a rare species, although sometimes locally common. It is restricted to two disjunct regions in Florida. Most Gulf coast populations grow in moist flatwoods or adjacent to wet cypress depressions; Atlantic coast populations occur in interdune swales.

4.   Calamovilfa arcuata K.E. Rogers
Cumberland Sandreed

Rhizomes short, covered with the persistent bases of the foliage leaves. Culms to 1.5+ m. Sheaths to 22 cm; ligules to 0.7 mm; blades to 85 cm long, 1.5-6.5 mm wide. Panicles 15-45 cm long, 8-40 cm wide, open; branches to 22 cm, ascending to spreading. Spikelets 6-7.4 mm. Glumes usually arcuate, acute to acuminate; lower glumes 2.7-4.1 mm; upper glumes 4.2-5.4 mm; callus hairs 1/3-1/2 as long as the lemmas; lemmas 5.5-7 mm, arcuate, pubescent, attenuate; paleas 5.4-6.2 mm, pubescent; anthers 2.8-3.2 mm. 2n = unknown.

Calamovilfa arcuata is known only from a few scattered locations in the south central United States. It grows along streams and rivers.

5.   Calamovilfa brevipilis (Torr.) Scribn.
Pine-Barren Sandreed

Rhizomes short, covered with the persistent bases of the foliage leaves. Culms to 1.5 m. Sheaths to 30 cm; ligules to 0.5 mm; blades to 50 cm long, 2-5 mm wide. Panicles 8-40 cm long, 4-20 cm wide, open; branches to 17 cm long, ascending to spreading. Spikelets 4-5.8 mm. Glumes straight, acute; lower glumes 1.7-4.1 mm; upper glumes 3.3-5 mm; callus hairs 1/4-1/2 as long as the lemmas; lemmas 4-5.4 mm, straight, slightly to markedly pubescent, acuminate; paleas 3.8-5.3 mm, slightly to markedly pubescent; anthers 2.4-3.2 mm. 2n = unknown.

Calamovilfa brevipilis grows in moist to dry pine barrens, savannahs, bogs, swamp edges, and pocosins. It is a common grass on the New Jersey pine barrens and locally common across the coastal plain of North Carolina, but rare at present in Virginia and South Carolina. The length of the ligule hairs tends to increase from 0.3 mm or less in the north to 0.5 mm at the southern end of its range.