Heracleum spp.
Family: Apiaceae
Heracleum image
Max Licher  
Fr elliptic to obovate, strongly flattened dorsally, usually pubescent, the lateral ribs broadly winged, the others filiform; oil-tubes 2-4 on the commissure, solitary in the intervals, extending only part-way from the stylopodium toward the base of the fr, readily visible; carpophore bifid to the base; umbels large and compound, with numerous unequal rays; bracts lanceolate, deciduous; umbellets many-fld; bractlets linear; sep minute or none; pet white; outer fls of at least the marginal umbellets irregular, the outer pet enlarged and often bifid; tall, stout biennials and perennials with large, ternate or once pinnate lvs and broad, toothed or cleft lfls, the petioles sheathing and usually conspicuously expanded. 60, circumboreal, only one native to N. Amer.

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 Naturalized flora of The Morton Arboretum