This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", 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..
Monoecious perennial herbs, with matted rootstocks, the sterns procumbent or ascending, leafy above, scaly or naked below. Leaves alternate, exstipulate, petioled, persistent, broad, 3-nerved, coarsely toothed, or entire. Flowers spicate, the pistillate and staminate in the same spike. Staminate flowers with 4 sepals; stamens 4, opposite the sepals; filaments thick, long-exserted; anthers 2-celled, the sacs longitudinally dehiscent. Pistillate flowers with 4 sepals or more; ovary 3-celled, the cavities with a partition at the base; styles 3, spreading; ovules 2 in each cavity. Capsule of 3 2-seeded carpels. [Greek, thick stamen.]
Two species, the following typical one of southeastern North America, the other Japanese.
P. procumbens Michx. Fl. Bor. Am. 2: 177. pl. 45. 1803.
Somewhat pubescent, forming large clumps; stems stout, simple, 1° long or less. Leaves ovate, oval, or obovate, 2'-4' long, obtuse or acutish at the apex, coarsely dentate or some of them entire, cuneate or abruptly narrowed at the base into a petiole shorter than or equalling the blade; spikes 1 or several in the axils of the lower scales, densely many-flowered, 2'-3' long, the staminate flowers forming most of the spike, the pistillate few toward its base; sepals green or purplish; filaments white, 4"-5" long.