Chenopodium . Leaves and top of plant x 0.5. - A: G Chenopodium hybridum (U). - B: Chenopodium vulvaria (£/).- C: (EH, U). - D: Chenopodium ficifolium subsp. ficifolium (U). ILL. MARJA KOISTINEN
Chenopodium pratericola is similar to narrow-leaved forms of the following species: G Chenopodium album (15), Chenopodium striatiforme (17), Chenopodium strictum (18) and Chenopodium virgatum (rare casual); however, these species are less silvery, the leaf apex is obtuse to acute (sometimes mucronate but not apiculate), and the stem is often red-tinged. Further, in these taxa the seeds are either broadly ovate in outline or larger ( Chenopodium album ).
Biology. In contrast to many other casual
Chenopodium species apparently sometimes setting seed in Norden, especially in the southern parts.
Distribution and habitat. A casual grain and cotton alien mainly recorded from ports, tips and chicken-runs; now very rarely seen. - D first record from 1894; NJy Thisted 1928, �lborg several records 1933-57, ØJy c. 5 localities, latest �rhus 1972, SJy �benr� 1939, FyL 3 localities, latest Svendborg 1961, Sjce 15 localities, mainly in the København area, latest Hvidovre 1975, LFM 4 localities, latest Stubbekøbing 1963. N fairly many records from mills and poultry farms in 0f, Ak, from VA to Ho, and in STSkaun, first in the 1920's; also on ballast in Ak Oslo 1903, 1905 and again in 1969 (from seed bank). S Sk at least 13 localities, latest Landskrona 1968, Bl Karlskrona 1938, Klm Kalmar 1921, Smi Bergunda 1924, Jönköping 1922, 1926, Källeryd 1926, Hl 5 localities, last Hanhals 1959, BhG c. 15 localities 1920 ’s-50’ s, Göteborg 1989, Vg Björketorp 1932, Ög Norrköping 1908, Sund 1930, Srm Eskilstuna 1999, Nyköping several records 1906-21 (with cotton), Nacka several records 1894- 1932, Salem 1919, Upl several localities around Stockholm and Uppsala, last 1952, Järlåsa 1923, Norrtälje 1925, Gst Gävle several records 1919-29, His Hudiksvall 1953, Mpd Skön 1911, Sundsvall 1922,7L Abisko 1927. A report from Vrm (Anonymous 1994) is due to misidentification. F first recorded 1904 but mainly in the period 1948-55; later on infrequent; c. 50 records from c. 20 places north to OP, more than half from Helsinki and Turku. I INo Akureyri 1950.
North America; a fairly frequent incomer in Europe.
Therophyte (summer-annual). Up to 1 m, young stems, inflorescences and lower surfaces of leaves usually conspicuously grey-farinose. Stem subangular, striped with green, without red colour, usually erect, branched in the middle and upper parts. Leaves with petiole up to 1(-1.5) cm; blade narrowly elliptic-ovate to narrowly trullate or lanceolate (wider leaves with a lobe-like tooth c. 1/3 from the base on one or both margins), 3-5(-6) x 0.4-1.5(-2.5) cm; base gradually tapering to the petiole; apex obtuse to acute, usually apiculate to mucronate; margin entire. Inflorescences axillary and terminal, panicle-like; glomerules small. Flowers mostly bisexual. Tepals 5, densely farinose, not covering the fruit at maturity, keeled, with wide membranous margin and ± obtuse apex. Stamens 5. Stigmas 2, c. 0.5 mm. Nut falling with the perianth; pericarp fairly easily detached. Seed horizontal, orbicular in outline, 0.8-1.1 mm; edge rounded; seed-coat black, glossy, rugulose. - Autumn. [2n=18]
Chenopodium pratericola is the most widespread member of a critical North American group of narrow-leaved species. There are different views on how this group is best treated taxonomically. In the narrow sense G Chenopodium pratericola has fairly large, thin leaf-blades which are fairly sparsely farinose on the upper surface and have 1 or 2 prominent, lobe-like teeth in the basal half, and moderately strongly keeled tepals. The closely related G Chenopodium desiccatum (less weedy, with a more limited distribution in W North America) has thicker, more farinose, entire leaves and more strongly keeled tepals. Many Nordic specimens (especially small ones) have extremely narrow leaves without teeth; there are plants which are very farinose on stems, leaves and tepals as well as ones which are only a little farinose. Possibly different taxa have occurred in Norden, but because the specimens are usually in vegetative or early flowering state they cannot be determined with certainty. For this reason G Chenopodium pratericola must be taken in a wide sense here. Fig. 9. Chenopodium . Leaves and top of plant x 0.5. - A: G Chenopodium hybridum (U). - B: Chenopodium vulvaria (£/).- C: (EH, U). - D: Chenopodium ficifolium subsp. ficifolium (U). ILL. MARJA KOISTINEN Nomenclatural confusion has also occurred; the name Chenopodium leptophyllum has often been used for the species occurring in Norden, but belongs to a different species which is also related to C. pratericola. - If G Chenopodium desiccatum and C. pratericola prove to be conspecific the oldest name for the taxon is from 1902.
Rydberg, Bull. Torrey Bot. Club 39: 310 (1912)
Literature. Bassett & Crompton 1982, Crawford 1975, Reynolds 6 Crawford 1980.