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..
Low annual branching herbs, with small narrow alternate entire toothed or lobed leaves, and polygamous or perfect flowers in small axillary clusters. Calyx of a single persistent herbaceous sepal. Stamen I. Styles 2, slender. Utricle flat, the pericarp adherent to the smooth vertical seed. Embryo a very nearly complete ring in the mealy endosperm, its radicle turned downward. [Greek, single-scale, from the solitary sepal.]
1849. Monolepis Nuttalliana Greene, Fl. Fran. 168. 1891.
Slightly mealy when young, pale green, glabrous or nearly so when old; stem 3'-12' high; branches many, ascending. Leaves lanceolate in outline, short-petioled, or the upper sessile, 1/2'-2 1/2' long, narrowed at the base, 3-lobed, the middle lobe linear or linear-oblong, acute or acuminate, 2-4 times as long as the ascending lateral ones; flowers clustered in the axils; sepal oblanceolate or spatulate, acute or subacute; pericarp minutely pitted, about i" broad; margins of the seed acute.