12.
Silphium asteriscus
Linnaeus, Sp. Pl. 2: 920. 1753.
Starry rosinweed
Plants
caulescent, 30—200 cm; fibrous rooted.
Stems
terete, glabrous, hirsute, hispid, or scabrous.
Leaves:
basal persistent or caducous, petiolate or sessile; cauline alternate, opposite, or whorled, petiolate or sessile; blades simple, lanceolate, falcate, or ovate, 1.5—25 × 0.5—5 cm, bases attenuate to round, margins dentate, serrate, or entire, apices acuminate, acute, or obtuse, faces glabrous, hirsute, hispid, or scabrous.
Phyllaries
12—26 in 2—3 series, outer appressed or reflexed, apices acute to acuminate, abaxial faces hispid or scabrous.
Ray florets
8—21; corollas yellow.
Disc florets
35—150; corollas yellow.
Cypselae
6—15 × 4—11 mm;
pappi
0—5 mm.
Varieties 5 (5 in the flora): e United States.
