Chenopodium polyspermum

Jonsell, B., Karlsson, 2005, Chenopodiaceae - Fumariaceae (Chenopodium), Flora Nordica (2), pp. 4-31 : 15-16

8. Chenopodium polyspermum L, Figs 2 H, 7

Linnaeus, Sp. pi.: 220 (1753). - Type: Linnaean Herbarium 313.19 (LINN) lectotype, sei. by Larsen, Fl. Cambodge, Laos, Vietnam 24: 95 (1989).

D Mangefrøet Gåsefod. F hentosavikka. N frømelde.

S fiskmålla.

Therophyte (summer-annual). (2-)10-80(-100) cm, glabrous or very slightly farinose on young parts. Stem ± angular, green to red, hard, erect or sometimes procumbent, sparsely branched; lower branches (sub-) opposite, often long; secondary branches few. Leaves often tinged with brown or red; blades thin, glabrous or sparsely farinose below when young; margin entire. Lower leaves with 1-2.5 cm long petiole; blade broadly ovate to ovate, 1-6(-9) cm; apex apiculate or acute to obtuse or rarely emarginate. Middle leaves with narrower, more elliptic and more obtuse blade. Bracts elliptic, lanceolate or obovate.

2n=18 (F U, S Sk). - [2n=18]

Distribution. Nem-BNem(- SBor). - An archaeophytic weed in the south; in modern times brought in e.g. with grain, ballast and shipments to troops. - D fairly common to scattered on the islands and in 0 Jy and eastern SJy, elsewhere rare. N frequent and well established in the southeastern lowlands north to southern He and Op and south to VA; rare and casual in coastal provinces from Ro Stavanger to SF Lærdal and Jølster, and in STSkaun 1930 -37 (grain mill). S on the whole common, especially in farmland areas, north to BhG, Vg, southern Vsm and Gst, but fairly rare in parts of the southern uplands; rare north to southern Vrm, southeastern Dir and His; further north rare and ± casual near the coast; Jmt Brunflo 1930, Östersund 1935, PL Arjeplog 1941. F archaeophytic in the south; fairly common at least in V, U, southern St and southern EH \ further north mostly casual (tips, docks, or brought with wartime transports), known from EP Kaskinen, Kristiinankaupunki, Vaasa, PS Kuopio, Pieksämäki rural municipality, PK, KP ( ± established in Haapavesi and Raahe), Kn Hyrynsalmi, Kajaani, Paltamo, OP Oulu, PeP Kemi, Simo and KiL Muonio.

Habitat. Bare, damp to moderately dry soil; favoured by a good nutrient supply but apparently not strongly nitrophilous (e.g. only rarely seen at dung heaps). - Gardens, fields, roadsides, plantations, tips and filling soil; outside settlements ditch banks and gravelly lake-shores.

Variation. Under long-day conditions plants are usually green to reddish and the leaf-blades are ovate with acute apex, whereas under short-day conditions (in the autumn) plants are green and the blades are elliptic with obtuse apex. Forms which show the same characters independently of day-length may exist, but they cannot be distinguished among this photoperiodically determined variation, and no taxonomic recognition can be adopted. - Pollen, seed and inflorescence characters indicate that C. polyspermum has no close relatives.