Chenopodium ambrosioides L.

Jonsell, B., Karlsson, 2005, Chenopodiaceae - Fumariaceae (Chenopodium), Flora Nordica 2, pp. 4-31 : 27-28

22. Chenopodium ambrosioides L.

Linnaeus, Sp. pi.: 219 (1753).

- Type: Linnaean Herbarium 313.13 (LINN) lectotype, sei. by Brenan, Fl. Trop. E. Africa, Chenopodiaceae: 10(1954).

D Vellugtende Gåsefod. F sitruunasavikka. N sitronmelde.

S citronmålla.

Therophyte (summer-annual). Strongly aromatic, up to 60 cm, ± hairy and with subsessile glands especially on the lower leaf surfaces (almost absent on upper leaf surfaces); glands with pyriform head. Stem subangular, yellowish or striped with green, erect, branched. Leaves sessile or with a 0-5-1.5 cm long petiole; blade lanceolate to elliptic, 3-15 cm, coarsely serrate, sometimes incised or sinuate, pure green; base attenuate; apex obtuse to acute.

Inflorescences spike-like, bracteate or ebracteate; glomerules small. Flowers dimorphic. Terminal flowers bisexual, with 5 stamens; tepals 5, connate c. halfway. Lateral flowers female; tepals 5, united almost to the apex. Tepals glabrous to sparsely pubescent, often with subsessile glands, herbaceous. Stigmas 3-4, slender, c. 0.5 mm. Nut falling with the perianth; pericarp not adherent to the seed. Seed mostly horizontal, broadly ovate in outline, 0.7-0.9 mm; edge rounded; seed-coat brown, glossy, almost smooth. - Late summer to late autumn.

[2n=32]

Chenopodium hircinum

Chenopodium opulifolium

Distribution and habitat. Casual (ports, railway stations, warehouses, mills, factories, refuse tips, flower-beds); brought in e.g. with grain, wool, cork and seed of ornamentals. D NJy Alborg 1960, 0Jy Arhus 1963, 1969, 1971 and Vejle 1932 (mill), Sjæ København several records 1927-97, Sorø 1952, 1953 (with cork), LFM Nysted 1964. A report from NJy Frederikshavn (Hansen & Pedersen 1968) was based on a misidentification. N ST Skaun 1930 (mill; probably from South America). S Sk Lackalänga 1924-49 (wool refuse), Lund 1949, BhG Angered 1932, Backa 1936, Göteborg 1872, 1955-56, 1993, 1997, Tuve 1997, Mölndal 1931, Nödinge 1939, Upl Stockholm 1882 (ballast). Also reported from Hl Halmstad (Retzius 1774) but no specimens have been found. F U Helsinki 1937, 1938, EH Jokioinen 1961, Tampere 1973; probably with American grain.

Tropical America; cultivated for use as vermifuge and naturalized throughout the tropical and subtropical zones, also in Europe in the Mediterranean and locally in the central part.

Biology. Flowering, but probably not able to set seed in Norden.

Similar taxa. Chenopodium ambrosioides is similar to C. anthelminticum and C. multifidum (rare casuals).