Chenopodium ambrosioides L.
Mexican tea
Annual aromatic herb to c. 1 m tall; stems branched, glandular-scaly, puberulent (hairs septate), occasionally all glabrous. Petiole c. 3-25 mm long; lamina 2.5-13 × 1-5 cm, lanceolate, narrow-ovate or elliptic, usually deeply serrate-dentate, glabrous or puberulent, dotted with sessile glands below; base cuneate; apex acute or subacute. Infls long-paniculate, axillary or terminal, efarinose; cymes (glomerules) in sessile clusters along branches; infl. lvs subtending cymes small, linear to oblanceolate, entire or sinuate. Perianth segments 0.5-1 mm long, valvate or slightly imbricate, glabrous or puberulent, green with narrow hyaline margin, not keeled on back. Fr. incompletely invested by perianth; pericarp easily removed. Seed horizontal or vertical, 0.6-0.9-(1.2) mm diam., subglobose to subreniform; margins rounded; testa glossy dark brown, smooth.
N.: common from N. Auckland to Hawke's Bay, otherwise rare but occurring as far south as the Hutt Valley.
Tropical America 1853
Open waste places, roadsides, especially recently disturbed areas, also in sandy coastal areas behind beaches near settlements.
FL Jan-Jul.
Mexican tea is still often very localised, although it was introduced to N.Z. in the early period of European settlement. Some plants resemble var. anthelminticum (L.) Gray, sometimes accorded specific rank as C. anthelminticum L.; this var. has ± pinnatifid lower lvs, and very reduced infl. lvs. C. ambrosioides has a very distinctive and powerful smell. Another characteristic feature is the long filiform stigmas unlike those of any other sp. found in N.Z.
Another related, tropical American sp., C. multifidum L., was recorded from Wellington in 1896 as Roubieva multifida. The incomplete specimen upon which this record was based cannot be identified with certainty but it has the pinnately-lobed lvs with narrow segments and small axillary glomerules of fls which are 2 of the characters of this sp.
