73. Symphyotrichum lentum (Greene) G. L. Nesom, Phytologia. 77: 286. 1995.
Suisun marsh aster
Aster lentus Greene, Man. Bot. San Francisco, 180. 1894; A. chilensis Nees var. lentus (Greene) Jepson; A. chilensis var. sonomensis (Greene) Jepson
Perennials, 40–150(–200) cm, colonial; long-rhizomatous. Stems 1–5, ascending to erect, glabrous. Leaves thin, margins entire, apices acute, faces glabrous; basal withering by flowering, petiolate, blades linear to narrowly lanceolate, 100–150 × 5–10 mm, attenuate or cuneate, margins entire, apices acute, faces usually glabrous; proximalmost cauline usually withering by flowering, sessile, blades linear to narrowly lanceolate or oblanceolate, 50–90 × 5–8(–20) mm, bases attenuate or cuneate; distal sessile, blades 40–80 × 5–8(–15) mm, bases cuneate. Heads in paniculiform arrays, branches some at least 25 cm. Peduncles glabrous or sparsely villous, bracts 5–15, sessile, lance-linear to lanceolate, margins sometimes spiculate. Involucres campanulate, 5–8 mm. Phyllaries in 4–5 series, narrowly oblong (outer) to linear (inner), unequal (outer at least 3 times longer than wide), bases (outer) indurate 1 / 2 or less, margins scarious proximally, eciliate or ciliolate, green zones lanceolate to elliptic, apices acute to acuminate, faces glabrous. Ray florets 20–45+; corollas violet, laminae 10–18 × 1–2 mm. Disc florets 35–70+; corollas yellow, 5–7 mm, lobes triangular, 0.8–1.5 mm. Cypselae brown, cylindric to obovoid, not compressed, 3–4 mm, 2–4-nerved, faces glabrous or hairy; pappi white, 5–7 mm. 2n = 16, 64.
Flowering Jul–Aug. Salt marshes, wet grasslands; 0–200 m; of conservation concern; Calif.
Symphyotrichum lentum is known only from the Sacramento Valley, North Bay County, lower Sacramento River, and San Francisco Bay areas. Probable intergrades with S. chilense have been noted.