Cota

Perennials [annuals, biennials], [5-]30-90 cm (rhizomatous and/or stoloniferous; not notably aromatic). Stems 1-5+, ascending to erect, not much branched, ± villous to sericeous (hairs usually medifixed, rarely basifixed) [glabrescent, glabrate]. Leaves cauline; alternate; petiolate or sessile; blades obovate to oblanceolate or spatulate, (1-)2(-3)-pinnately[-subpalmately] lobed (primary lobes often pectinately divided), ultimate margins serrate or entire, faces ± villous to sericeous [glabrescent, glabrate]. Heads radiate [discoid], borne singly or in lax, corymbiform arrays (peduncles sometimes distally dilated). Involucres hemispheric or broader [obconic], [5-]10-12[-20+] mm diam. Phyllaries persistent, 40-75+ in 3-5 series, distinct, deltate to lanceolate (often cartilaginous medially), unequal, margins and apices scarious (apices often mucronate to spinose, abaxial faces usually villous to arachnose). Receptacles ± hemispheric, paleate (throughout); paleae (persistent) ± flat, often cartilaginous (each proximally elliptic to oblong, distally ± subulate to spinose). Ray florets [0] 12-21[-35+], pistillate and fertile, or styliferous and sterile; corollas yellow [white or pinkish], laminae oblong (often reflexed, marcescent in fruit). Disc florets 80-200+, bisexual, fertile; corollas yellow [pinkish], tubes ± compressed (bases not dilated, not clasping cypselae), throats funnelform, lobes 5, deltate (minutely crested abaxially near tips). Cypselae obconic to prismatic (± 4-angled), ± ob-compressed or -flattened, ribs 0 or 2 lateral (sometimes winged) plus 3-10 finer ribs or nerves on each face, faces glabrous (pericarps with myxogenic cells; embryo sac development tetrasporic); pappi [0] coroniform. x = 9.

Cota, sometimes a subgenus of Anthemis, is distinguished by its obcompressed and indistinctly ribbed cypselae; plants of Anthemis in narrow sense usually have ± terete cypselae with 10 distinct ribs. Additional differences include cytological, phytochemical, and molecular traits.

Apparently, Cota altissima (Linnaeus) Gay (Anthemis altissima Linnaeus) was reported from Oregon in error (L. Abrams and R. S. Ferris 1923-1960, vol. 4). No specimens of C. altissima from Oregon have been located, and the taxon has been specifically excluded from the Oregon Flora checklist (K. L. Chambers and S. Sundberg, www.oregonflora.org).

Cota austriaca (Jacquin) Schultz-Bipontinus (Anthemis austriaca Jacquin), a European species, has been reported as established near Pullman, Washington (specimen in UC); it differs from C. tinctoria in having an annual or biennial habit, subhirsute phyllaries, and white ray laminae (R. Fernandes 1976).