Chenopodium hybridum is vegetatively ± indistinguishable from the North American Chenopodium simplex (rare casual), but clearly different in seed characters.
Habitat. Gardens, vegetable-patches, parks, roadsides, waste ground (especially on heaps of soil); very rare as a field weed; earlier often near castles and rectories.
A. Wolfgang Adler & Alexander Ch. Mrkvicka 2003: Die Flora Wiens, gestern und heute: p.153, B. Jacques Lambinon & Filip Verloove 2012: Nouvelle Flore de la Belgique, du G-.D. de Luxembourg, du nord de la France et des Régions voisines, 6th: p.160, C. Daniel Jeanmonod & Jacques Gamisans 2007: Flora Corsica: p.328, D. Marie Zajac, Adam Zajac & Bogdan Zemanek 2006: Flora Cracoviensis Secunda: p.64
Europe, except for the northernmost parts, rare in the Mediterranean and in the southeast; the Caucasus, Siberia, China.
Distribution. Nem-BNem[-SBor]. - Probably archaeophytic in the south, but largely a recent incomer, at least partly brought in with garden plants, and formerly with ballast. - D weakly established archaeophyte; scattered on the islands and in 0Jy; rare in NJy; VJy Tarm 1967, SJy Sønderborg c. 1890, 1986. N mainly in the southeastern lowland, established but declining; also AA Tvedestrand 1889, Ro Stavanger 1875, Ho Osterøy 1930, Ullensvang 1936, Bergen 1971, SF Jølster 1971, MR Stranda 1917. S probably archaeophytic only in the south and southeast; apparently increasing but often ephemeral at individual localities; scattered north to Vg, Ög and Upl (now fairly common in the Stockholm area); rare and usually casual further north: Dls Gunnarsnäs 1908, Vrm Karlstad (several records 1888-1933), Brattfors 1995, Vsm (7 localities) and southeastern Dir (established); along the coast in Gst Gävle several records 1810-1985, His Hudiksvall, Järvsö, Rogsta (all before 1911), Mpd Timrå 1898, 1913, 1961, �ng Härnösand 1932 and Nb Piteå 1908. F ± established in A Kökar, V Turku (and at least formerly in the archipelago) and t/, elsewhere casual; scattered in coastal towns north to KP Kokkola 1950 and OP Oulu 1894, 1901; very rare inland (St Lappi 1959, EH at least 8 municipalities, ES Mikkeli rural community 1964, PH Äänekoski 1938, Viitasaari 1974); mainly with ballast and war-time transports.
Therophyte (summer-annual). Sparsely farinose to subglabrous, with slightly unpleasant odour, (10-) 20-100 cm. Stem distinctly angular, yellowish green and usually striped with dirty green (rarely tinged with red), hard, erect, branched mainly in the upper part. Leaves with petiole 1/2 to 2/3 as long as the blade; blade broadly ovate to broadly triangular, (2-)4-15 (-19) cm; base ± cordate to subtruncate; each margin with 1-3 acute or acuminate lobes (or large teeth). Bracts lanceolate, with a pair of basal teeth or sometimes entire. Inflorescences terminal and axillary, divaricately branched, mono- or dichasial; cymes ± reduced and condensed, glomerules fairly small. Flowers usually bisexual. Tepals 5, connate less than halfway, spreading in fruit, keeled, with membranous margin and obtuse apex; a strong rib visible inside. Stamens 5. Stigmas 2 or rarely 3, 0.2-0.3 mm. Nut falling with or without the perianth; pericarp firmly adherent to the seed. Seed horizontal, orbicular in outline, 1.6-2 mm; edge rounded; seed-coat black, with large, deep, ± isodiametric pits. - Mid-summer to late summer. 2n=18 (S Sk 2). - [2n=18]
Variation. In Europe and North America the
Chenopodium hybridum aggregate comprises two well-delimited taxa, viz. Chenopodium hybridum in Europe and Chenopodium simplex (see rare casuals) in North America. In Asia it is represented by several taxa. A specimen from S Upl Sollentuna (Rotebro) 1925 belongs to one of these, having large leaf-blades and large seeds with coarsely rugulose but not pitted seed-coat.
D Hjertebladet Gåsefod. F vaahterasavikka. N hjertemelde. S lönnmålla.
Chenopodium murale Chenopodium hybridum