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..
Tall leafy herbs, perennial by thick rootstocks, the stem, at least its upper part, and the inflorescence, pubescent. Leaves narrow, oblanceolate or linear, sheathing or the upper sheath-less. Flowers greenish, white or cream-colored, darker in withering, monoecious or polygamous, slender pedicelled in a large terminal panicle. Perianth of 6 spreading separate persistent clawed 2-glandular segments, mostly free from the ovary. Stamens shorter than the segments and adnate to them; anthers cordate or reniform, their sacs confluent. Ovary ovoid; styles 3, subulate, spreading. Capsule 3-lobed, 3-celled, the cavities several-seeded, tipped by the style. Seeds very flat and broadly winged, several in each cavity. [Greek, signifying black flower.]
Blade of the perianth-segments oblong, entire; leaves linear.
Blade of the perianth-segments nearly orbicular, undulate; leaves oblanceolate.
Melanthium virginicum L. Sp. PI. 339. 1753.
Stems rather stout, 21/2°-5° high. Leaves linear, acuminate, often 1° long, 4"-12" wide, the lower sheathing, the upper smaller, sessile, the uppermost very small; panicle 6-18' long, usually much longer than the ovate-oblong bracts; flowers 6"-10" broad, greenish yellow, turning brown; perianth-segments obtuse, the blade oblong, flat, entire, sometimes obcordate, at least twice as long as the claw, bearing 2 dark "lands at its base; capsule 5"-7" long, the persistent styles erect, 1"-l 1/2" long; seeds 8-10 in each cavity, 2"-3" long.
?Melanthium hybridum Walt. Fl. Car. 125. 1788.
M, latifolium Desr. in Lam. Encycl. 4: 25. 1797.
Stem stout or slender, 2°-4° tall. Leaves ob-lanceolate, acute, 6"-2' wide, the lower clasping, the upper sessile and much smaller; panicle usually 1° long or more, its branches ascending or spreading; flowers 6"-8" broad, greenish white, turning darker; blade of the perianth-segments orbicular or ovate, undulate and crisped, longer than the claw or about equalling it, bearing 2 glands at the base; capsule 6"-8' long, its cavities 4-8-seeded; seeds rather larger than those of the preceding species; flowers fragrant.
In dry woods and on hills, Connecticut to Pennsylvania and South Carolina. Ascends to 2000 ft. in North Carolina. Pedicels 3"-8" long. July-Aug.