15. Chenopodium album Linnaeus, Sp. Pl. 1: 219. 1753.
Herbs annual, 15-150 cm tall. Stem erect, much branched, green or purple-red striate, stout, ribbed; branches oblique or spreading. Leaf blade rhombic-ovate to broadly lanceolate, 3-6 × 2.5-5 cm, 1-2 × as long as petiole, abaxially ± farinose, adaxially usually glabrous, or sometimes reddish purple vesicular hairy on young leaves, base cuneate to broadly so, margin irregularly serrate, apex subobtuse or acute. Glomerules arranged into large or small panicles or spikelike panicles on upper part of branches. Flowers bisexual. Perianth segments 5, broadly ovate to elliptic, abaxially longitudinally keeled, farinose, margin membranous, apex acute or slightly emarginate. Stamens 5; anthers exserted. Stigmas 2. Pericarp adnate to seed. Seed horizontal, black, sublustrous, lenticular, 1-1.5 mm in diam., lineate, rim margin obtuse. Fl. and fr. May-Oct.
Fields, waste places, roadsides, a difficult weed to control. Throughout China [probably throughout temperate and tropical regions of the world].
Chenopodium album s.l. in its more or less traditional circumscription is a diverse aggregate of predominantly hexaploid (2n = 54) taxa. It is represented in China by many insufficiently known and poorly delimited infraspecific entities. Some of them are, however, rather distinct from European plants. The taxonomic situation is further obscured by exceptional variability and widespread hybridization in the group. Consequently, no attempt has been made here to classify the Chinese infraspecific entities of C. album s.l. The precise global distribution is uncertain because many plants reported as C. album in the literature in fact belong to other, closely related species.