Calycadenia oppositifolia (Greene) Greene

Calycadenia oppositifolia is known only from the Sierra Nevada foothills of Butte County. Its closest relative may be C. multiglandulosa.

Plants 10–30 cm; self-incom-patible. Stems simple or sparingly branched (very slender), strigose and sparsely spreading-hairy. Leaves mostly or all opposite, 1–5 cm (little reduced distally), strigillose and ± long-hairy (at least proximally). Heads in congested, axillary glomerules (appearing whorled). Peduncular bracts lanceolate (flat, stiff, sometimes ± cylindric near apices), 4–10 mm (hispidulous, ± bristly and/or pectinate-fimbriate, especially proximally), apices ± rounded, tack-glands (0–)1–5+. Phyllaries (often reddish) 4–7 mm, abaxial faces sometimes minutely scabrous, often sparsely bristly, tack-glands usually 0, sometimes 1+. Paleae 4–7 mm. Ray florets 2–4; corollas white to reddish, tubes ca. 2 mm, laminae 6–9 mm (central lobes ± equaling or narrower than laterals, elliptic, nearly symmetric, widest near middles, sinuses equaling laminae). Disc florets 4–20; corollas white to pink, ca. 6 mm. Ray cypselae ca. 3 mm, usually smooth, glabrous. Disc cypselae ca. 3 mm, ± appressed-hairy; pappi of 8–10 usually lanceolate, acuminate scales ca. 2 mm (often 2–4 shorter, blunt). 2n = 14.

Hemizonia oppositifolia Greene, Bull. Torrey Bot. Club 9: 110. 1882

Calycadenia oppositifolia is a species of flowering plant in the family Asteraceae known by the common name Butte County western rosinweed. It is native primarily to Butte County, California, although a few populations have been found in other parts of the state. It grows in the foothills of the high mountain ranges.

Calycadenia oppositifolia là một loài thực vật có hoa trong họ Cúc. Loài này được (Greene) Greene mô tả khoa học đầu tiên năm 1897.