Chenopodium album L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Erect annual, much branched and to 1 m when well developed, the stems only seldom pigmented at the nodes, the lvs and infl often turning reddish late in the season; lvs generally ± white-mealy, rhombic-ovate to lanceolate, 3–10 cm, broadly cuneate at base, the larger (lower) ones mostly 1.5–2+ times as long as wide and almost always toothed; fls in dense glomerules, forming interrupted or continuous spikes that are grouped into a terminal paniculiform infl; cal ± white- mealy, its segments ± strongly carinate or cucullate, covering the fr, or sometimes looser and exposing the fr; style divided to the base, wholly deciduous; pericarp very thin and delicate, closely adherent to the seed and usually scarcely separable from it, smooth or only obscurely roughened when viewed at 10× or even 20×, uniformly black or blackish; seeds horizontal, black, shining, mostly 1.0–1.5 mm wide, usually marked with a faint radial furrow, otherwise smooth or nearly so; 2n=54. June–Oct. Polymorphic European weed, now widely intr. in N. Amer. and elsewhere. Sometimes divided into an indefinite number of infraspecific taxa or specific segregates. (C. glaucophyllum; C. lanceolatum, a relatively narrow-lvd form) In our range the two following segregates are particularly noteworthy and probably merit some sort of taxonomic recognition.
lamb's quarters, pigweed