Ptilimnium nuttallii (Dc.) Britton

Slender, 3–7 dm, branched above; lvs 3–10 cm, pinnately dissected into filiform segments 1–6 cm, the primary divisions alternate or opposite on the rachis; petiole to 1 cm, winged its whole length; umbels 2–6 cm wide; bracts filiform, usually entire; rays 15–30, slender, 1–3 cm; fr subglobose, 1.5 mm; styles 0.5–1.5 mm, strongly recurved at maturity; 2n=14. Wet soil; Tex. and La. to Kans. and Mo., almost entirely s. of the Missouri R. June, July.