Chenopodium L.
Annual or perennial herbs, occasionally shrubby, glabrous, farinose, or with very short glandular hairs. Stems usually green, often whitish farinose when young, sometimes striped yellow, red or purple. Lvs mostly alternate, sometimes opposite near base, flat, extremely variable in shape, usually membranous. Fls usually in glomerules, sessile, ⚥ or ♀; glomerules aggregated in dense spikes or panicles; bracteoles 0. Perianth segments 2-5, usually herbaceous, incurved, connate at base, scarcely accrescent, rarely becoming fleshy. Stamens (1)-2-5. Ovary superior; stigmas 2-(5). Fr. indehiscent with a membranous pericarp, often surrounded by persistent perianth. Seed generally horizontal, sometimes vertical; testa variously sculptured.
Key
100-150 spp., temperate regions, often coastal. Native spp. 3, naturalised 11.
The diagnostic characters of the testa can only be seen under a magnification of at least ×40, and only after the pericarp has been removed by rubbing, scraping, or even boiling for spp. in which it is very persistent. Chenopodium spp. are well-adapted to grow in open, disturbed habitats. Most were presumably introduced accidentally to N.Z. in ballast, crop seed or other imported goods.
The genus has been divided into 13 sections by Aellen, P., in Hegi, G., Ill. Fl. Mitteleur. 3(2), ed. 2 (1975-1979). Certain of the spp. in N.Z. have been considered to represent the genus Teloxys Moq.; this separation has been recently supported by Weber, W. A., Phytologia 58(7): 477-478 (1985), who put Allen's first 5 sections into it and made new combinations for several spp. recorded in N.Z. The distinguishing characters of Teloxys are the presence of glandular hairs and oils giving a pungent aroma (not to be confused with the presence of trimethylamine; see under C. vulvaria), the absence of glandular vesicles (farina), the lvs nearly always pinnatifid or pinnatisect, the stamens exserted and the embryo not completely encircling the endosperm. The spp. concerned in N.Z. are all those included in the second part of the first couplet in the key, as well as those mentioned incidentally in their notes.
The genus Einadia is closely related to Chenopodium and 2 of its spp. may be easily confused with it. They would probably key to the rare Chenopodium spp., C. detestans and C. vulvaria, but can easily be distinguished from these because they lack the revolting smell of dead fish that the 2 Chenopodium spp. have.
