Plants 3-50[-70] cm. Stems usually 1, erect; branches leafy between proximal forks, remaining grayish to whitish, lanuginose to sericeous. Leaves oblanceolate to lanceolate, largest 14-20(-40) × 3-4(-5) mm, pliant; longest capitular leaves 0.8-1.5(-2) times head heights, acute. Heads mostly in glomerules of 2-10(-13) in racemiform to paniculiform arrays, broadly pyriform to ± cylindric, largest 4-6 × 3.5-5 mm. Phyllaries 0, vestigial, or 1-4, unequal, ± like paleae. Receptacles ± fungiform, 0.4-0.7 mm, heights 0.4-0.5 times diams. Pistillate paleae (except innermost) 2-4(-6) in 1(-2) series, spirally ranked, loosely saccate, incurved 20-60°, scarcely gibbous, not galeate, longest 3.3-4.5 mm, distal 5-10% of lengths glabrous abaxially; bodies ± cartilaginous, ± terete; wings obscured by indument. Innermost paleae ± 8, spreading in 2 series, pistillate. Pistillate florets: outer 2-4(-6) epappose, inner 15-20 pappose. Bisexual florets 3-4; corollas 2.3-3 mm, lobes mostly 4, reddish to purplish. Cypselae: outer nearly straight, ± erect, compressed, 0.9-1.1 mm; inner papillate; pappi of 17-23 bristles falling in complete or partial rings, 2.5-3.5 mm. 2n = 28 (Caucasus, Finland, Germany, Slovakia).
Flowering and fruiting mid Jun-mid Sep. Open, sandy to gravelly soils, disturbed sites (road and ditch banks, lakeshores, clear cuts, old fields, dwellings, grazed lands); 100-1700 m; introduced; B.C., Sask.; Alaska, Idaho, Mich., Minn., Mont., Nebr., Oreg., S.Dak., Wash., Wyo.; Eurasia; nw Africa.
Logfiaarvensis appears to be basal or nearly so in Logfia and Filagininae (J. D. Morefield 1992); only 2-4 epappose florets are present in most heads. Reports of L.arvensis from Ontario and New York have not been confirmed by me. A report from the Desert National Wildlife Range in southern Nevada (T. L. Ackerman et al. 2003) was likely based on specimens of L.filaginoides. The earliest specimen confirmed from the flora area was from Bonner County, Idaho, in 1934. The label on one nineteenth-century specimen (mixed with Diaperia verna) identifying it as coming from Dallas, Texas, is probably in error; no other collections of L. arvensis are known from in or near Texas.