Bacopa rotundifolia (Michaux) Wettstein. Common name: Midwestern Water-hyssop. Phenology: May-Sep (-Nov). Habitat: Tidal muds, shallow water of large natural lake, river sandbars, other shallow water and shore situations. Distribution: Indiana and Iowa west to North Dakota and Montana, south to Alabama and Arizona; disjunct in e. Maryland, e. Virginia, ne. North Carolina, and e. South Carolina (Bradley et al. [in prep.]), where apparently native, though Cronquist (1991) considered introduced. Known in North Carolina only from Lake Mattamuskeet, Hyde County, and "north of Wilmingon); not recently seen.
Origin/Endemic status: Native
Taxonomy Comments: B. simulans Fernald has been considered a rare endemic of tidal areas in VA and MD. It is alleged to differ from B. rotundifolia in its glabrous to glabrescent stems (vs. pubescent), more succulent condition, smaller leaves (the larger 1-2 cm long and 0.6-1.5 cm wide vs. 2-3.5 cm long and 1.5-2.7 cm wide), smaller flowers (corolla 3-4 mm long vs. 6-10 mm long). Schuyler (1989) concluded that B. simulans is an intertidal form of B. rotundifolia, the morphologic differences the result of differences in inundation. Additional work, perhaps involving growth under experimental conditions or chemical or molecular studies, is needed to corroborate Schuyler's conclusion. See Schuyler (1989), F, and Fernald (1942) for further discussion.
Synonymy ⓘ: = Ar, C, Can, FNA17, GrPl, GW2, Il, K1, K4, Mo3, NcTx, NS, POWO, Tn, Tx, Schuyler (1989), Tippery et al (2024); = Macuillamia rotundifolia (Michx.) Raf. — S, Pennell (1935); = n/a — RAB, Tat; > Bacopa rotundifolia (Michx.) Wettst. — F, G; > Bacopa simulans Fernald — F, G. Basionym: Monniera rotundifolia Michx. 1803
Links to other floras: = Bacopa rotundifolia - FNA17
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Wetland Indicator Status:
- Atlantic and Gulf Coastal Plain: OBL
- Eastern Mountains and Piedmont: OBL
- Great Plains: OBL
- Midwest: OBL
- Northcentral & Northeast: OBL
Heliophily ⓘ: 8
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© Keith Bradley | Original Image ⭷
© Keith Bradley
© Keith Bradley | Original Image ⭷
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