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FNA | Family List | FNA Vol. 21 | Asteraceae | Silphium

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.


1 Leaf faces glabrous or sparsely hairy   (2)
+ Leaf faces hirsute, hispid, or scabrous   (3)
       
2 (1) Cauline leaves mostly whorled (in 3s)   12a Silphium asteriscus var. trifoliatum
+ Cauline leaves mostly opposite   12b Silphium asteriscus var. latifolium
       
3 (1) Basal leaves persistent   12c Silphium asteriscus var. simpsonii
+ Basal leaves caducous.   (4)
       
4 (3) Paleae puberulent and stipitate-glandular   12d Silphium asteriscus var. dentatum
+ Paleae puberulent to scabrous (not glandular)   12e Silphium asteriscus var. asteriscus


 

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