Chenopodium urbicum L.

Jonsell, B., Karlsson, 2005, Chenopodiaceae - Fumariaceae (Chenopodium), Flora Nordica 2, pp. 4-31 : 14-15

7. Chenopodium urbicum L. Figs 2G, 6B

Linnaeus, Sp. pi.: 218 (1753).

- Type: Linnaean Herbarium 313.2 (LINN) lectotype, sei. by Uotila, Ann. Bot. Fenn. 30: 190 (1993).

D Rank Gåsefod. F kyläsavikka. N bymelde. S bymålla.

Literature. Nilsson & Gustafsson 1979.

Therophyte (summer-annual). 10-60(-100) cm, glabrous or sometimes farinose, olive-green or sometimes brownish. Stem angular, yellowish, never red in the leaf axils, hard, erect, sparsely branched. Lower and middle leaves with petiole less than half as long as the blade; blade fairly thick, ± broadly triangular, sometimes as wide as long, often with outward-pointing basal lobes, 3-10(-18) x 3-8(-20) cm; base ± truncate (slightly cuneate to slightly cordate); apex obtuse or sometimes acute; margin sinuate to dentate with teeth pointing outwards or sometimes recurved, or rarely subentire; teeth at the widest point of the blade larger than the others. Upper leaves with narrowly triangular to trullate or lanceolate blade.

Inflorescences axillary and terminal, erect, spikelike, ebracteate; glomerules very small, dense. Flowers monomorphic, bisexual or female. Tepals 5, connate at base, not keeled, with wide membranous margin; apex obtuse. Stamens 5. Stigmas 2 or sometimes 3, 0.1 mm. Nut falling with or without the perianth; pericarp not or weakly adherent to the seed. Seed horizontal, orbicular in outline, 1-1.2 mm; edge rounded; seed-coat black, glossy, almost smooth to obscurely reticulate or rugulose. - Mid-summer to early autumn.

[2n=36]

Distribution. Archaeophytic at least in parts of F and S (but now extinct); also a casual alien, in D and N perhaps never established. - D ØJy Vejle 1930, 1932, �rhus 1999, FyL Svendborg 1905; Sjce København 1985, Farum 1990-97 (with compost from the botanic garden in København); a few records from Sjæ, LFM and Brn in the period 1825-1939. N 0/Halden 1827, Ak Oslo and Bærum (both before 1900), Ho Etne 1959 (poultry farm). S formerly scattered to rare north to Vrm, Vsm and Gst and fairly abundant in some towns (e.g. Gtl Visby, Upl Uppsala), nowadays disappeared, last seen as established in Vsm Bro 1987; casual north to Mpd and in Nb\ most recently recorded, as a casual, in Bl Ramdala 1989, Kim Torsås 1999, Smi Tingsås 1999, 2000, BhG Göteborg 1993 and Nb Nederkalix 1997. F in the 19th century apparently ± established as an archaeophyte or a relatively old alien in some old towns and villages (at leasts Finström, Saltvik, Sund, Kumlinge, V Korppoo, Särkisalo, U Inkoo, Helsinki, Porvoo, Myrskylä, EK Kotka and EH Sysmä), now disappeared; casual occurrences, most often of Russian origin, after 1950 at least in U Helsinki 1950's to 1960's, EH Nokia 1972 (tip), Tampere 1961, 1963 (railway yard), 1976 (mill), ES Savonlinna 1950's (tip), EP Vaasa 1950's (docks), PK Värtsilä 1990 (railway yard) and OP Oulu 1960 (docks).

Europe (especially the SE part); from SW Asia to Siberia; also North America (not native).

Habitat. Very nitrophilous, but a poor competitor. Nitrogen-rich places in farmland (dungheaps, cowhouses and farmyards), in the 18th and 19th centuries also town streets; in the later part of the 20th century mainly as a casual (railway yards, ports, fields and grain mills). The disappearance is probably mainly due to improved sanitary conditions.

Variation. Variants based on differences in leaf shape have sometimes been recognized. Nordic plants have broadly triangular leaf-blades and seem to match var. urbicum fairly well.

Similar taxa. Chenopodium urbicum is similar to C. macrospermum (rare casual). - Sometimes mixed up with C. chenopodioides (4), C. murale (9), Atriplex prostrata and A. hortensis . The species of Atriplex can be distinguished even in the vegetative phase by (sub)opposite branches and leaves.