Angiosperms: Dicotyledons

Asteraceae
Daisy Family

• Stem: perennial; 3’ to 5’ tall; unbranched; smooth.
• Leaves: opposite; oval with rounded bases and pointed tips; sessile; 4” by 2” or narrower to 3 1/2” by 1”; margins sometimes with small teeth; rough with hairs above and below; often “cupped.”
• Inflorescence: one to a few flower stalks from the stem tip and upper leaf axils; heads on short, hairy stalks; five to ten heads per plant.
• Heads: pale yellow rays 3/4” by 1/4”; yellowish green disk flowers; head 2” across; fillaries oval and pointed, 1/2” tall, hairy; flowering from mid-July to late August.
• Fruits: “seeds” (fruits) flat, roundish, 3/8” long; no plume; only the outer flowers setting fruit; fruiting begins in early August.
• Habitat: frequent on dry to moist prairies; also on roadsides and sometimes in open woods.
• Notes: A variety, laeve T. & G. (Silphium speciosum Nutt.) (not recognized by Eilers and Roosa 1994), is found in several border counties in southwest Iowa. It is not hairy on the stem or fillaries, the leaves are less hairy, and the leaf margins are smooth.
• Bibliography from Biodiversity Heritage Library
• Vascular Plants of Iowa