Sium suave Walter. Water-parsnip. Phen: Jun-Aug; Aug-Oct. Hab: Freshwater marshes, brackish marshes, swamp forests, in tidally or seasonally flooded hydrology. Dist: NL (Newfoundland) west to AK, south to Panhandle FL, n. peninsular FL, and CA; e. Russia, China, Korea, and Japan.

ID notes: The plant can be very coarse, up to 3 m in height and the stem to 5 cm in diameter. Submersed leaves are deeply dissected.

Origin/Endemic status: Native

Taxonomy Comments: The taxonomic status of Sium floridanum Small, known from se. VA south to GA, needs additional investigation; it is probably just a depauperate shade form.

Synonymy ⓘ: = Ar, C, Fl7, FNA, GrPl, Il, K1, K3, K4, Mi, Mo2, NcTx, NE, NY, Pa, RAB, Tat, Tn, Tx, Va, W, WH3, WV; > Sium carsonii Durieu ex A.Gray; > Sium cicutaefolium Schrank – S; > Sium floridanum Small – F, G, GW2, MC, S; > Sium suave Walter – F, G, GW2, MC

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: OBL (taxonomic lump from wetland indicator species)
• Eastern Mountains and Piedmont: OBL (taxonomic lump from wetland indicator species)
• Great Plains: OBL
• Midwest: OBL
• Northcentral & Northeast: OBL (taxonomic lump from wetland indicator species)

Heliophily ⓘ: 7