Curlycup gumweed

General: aromatic plant, 20-60 cm tall.
Growth habit: biennial or short-lived perennial from taproot, branching from base, often growing in patches.
Stems: hairless, with many upper branches.
Leaves: oblong, 10-35 mm long and 6-12 mm wide, hairless, with small, hardened teeth, to sometimes more coarsely toothed or even entire, often dotted with resinous glands. Middle and upper leaves mostly clasping.
Flowerheads: yellow with 25-40 rays that are about 7-15 mm long. The disk is 1-2 cm wide. Involucre strongly resinous, with several overlapping rows of backward-curling bracts. Many heads growing in flat-topped clusters. 
Fruits: achenes, 4-5-ribbed, without 2 knobs on top of margin. Pappus of 2 or 3 slender bristles, soon dropped.