7.
Silphium integrifolium
Michaux, Fl. Bor.-Amer. 2: 146. 1803.
Wholeleaf rosinweed
Plants
caulescent, 40—200 cm; fibrous rooted.
Stems
terete to slightly square, sparsely scabrous or glabrous (sometimes glaucous).
Leaves:
basal caducous; cauline opposite, sessile; blades lanceolate to ovate, 2—23 × 0.1—11 cm, bases round to caudate, margins finely serrate or entire, apices acute to acuminate, faces hispid, scabrous, or glabrous.
Phyllaries
17—37 in 2—3 series, outer appressed, apices acute to acuminate, abaxial faces glabrous, hispid, pilose, or scabrous, sometimes stipitate-glandular.
Ray florets
12—36; corollas yellow.
Disc florets
70—225; corollas yellow.
Cypselae
9—14 × 6—10 mm;
pappi
1—4 mm.
Varieties 2 (2 in flora): e North America.
