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..
Fleshy herbs with bulbiferous rootstocks and bracted scapes, the leaves basal, and large bracted flowers in terminal spikes or racemes. Perianth tubular or funnelform, withering-persistent, of 6 erect or spreading equal or nearly equal lobes, united below into a tube. Stamens inserted on the perianth, exserted; filaments flattened or filiform; anthers versatile. Ovary 3-celled, style slender, exserted, 3-lobed; ovules numerous, in 2 rows in each cavity of the ovary. Capsule ovoid, subglobose or oblong, 3-lobed, 3-celled, thick-walled, many-seeded Seeds compressed. [Named for Manfred, an ancient Italian writer. }
Agave virginica L. Sp. PI. 323. 1753. M. virginica Salisb.; Rose, Contr. U. S. Nat. Herb. 8:
Glabrous throughout, rootstock a short crown with numerous fibrous roots.' Scape 2°-6° tall, rather slender, sometimes nearly 1/2' in diameter at the base, its bracts distant, long-acuminate, the lower 3'-6' long; leaves narrowly oblong, 1/2°-2° long, 1/2-2 1/2 wide, acuminate, their margins entire or denticulate; spike 1°-2° long, loose; flowers greenish yellow, odorous, solitary in the axils of short bracts, sessile or the lowest distinctly pedi-celled; perianth nearly tubular, slightly expanded above, 8"-12" long, the tube about twice as long as the erect lobes; filaments at length about as long as the perianth; capsule 5"-8" in diameter, slightly longer than thick, abruptly contracted into a short stalk.
In dry soil, Maryland to Indiana and Missouri, south to Florida and Texas. Rattlesnake's-master.