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Sium spp.
Family: Apiaceae
Sium image
© matthew_salkiewicz  
Fr somewhat flattened laterally, ovate to orbicular, slightly constricted at the commissure, the ribs prominent and corky; oil-tubes 1-3 per interval, 2-6 on the commissure; umbels terminal and lateral, compound, with 6-many rays; bracts 2-several, lanceolate, reflexed; umbellets compact; bractlets slightly smaller than the bracts; sep minute or none; pet white, the outer sometimes slightly enlarged; stylopodium mostly depressed; usually tall, branched, glabrous perennials (sometimes annual?) with once pinnate lvs and 5-many elongate serrate lfls. 8, N. Temp. and S. Afr.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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Species within South Dakota