Stems erect, purplish, 3–25 cm. Flowers: calyx lobing variable, some or all lobes usually distinctly connate proximally, forming sheath or tube, 1.5–3.2 × 0.5–1.1 mm, sheath or tube 0.5–3 mm; corolla 3–6.2 mm, lobed 0.5–0.7 times its length; anthers purple or occasionally yellow, 0.4–0.9 mm, apex rounded or mucronate.

Phenology: Flowering summer–fall.
Habitat: Conn., Maine, Mass., R.I., restricted to coastal sites southward..
Elevation: 0–400 m.

Distribution

• Generated Map
• Legacy Map

St. Pierre and Miquelon, N.B., Nfld. and Labr. (Nfld.), N.S., Conn., Maine, Mass., R.I., restricted to coastal sites southward.

Discussion

In some respects, subsp. iodandra is intermediate between subsp. paniculata and Bartonia virginica, and for that reason it was treated by A. Haines (2011) as a species derived from past hybridization of those taxa. The range of subsp. iodandra extends well beyond that of either subsp. paniculata or B. virginica, completely displacing subsp. paniculata in the northern part of the range of the species as circumscribed here. It appears that although some plants that have been called subsp. iodandra may be derived from hybridization, most plants of subsp. iodandra are sufficiently similar to subsp. paniculata and sufficiently distinct from B. virginica to justify their retention in B. paniculata. Morphologically, the more abruptly tapering corolla lobes of subsp. iodandra might be assumed to be attributable to such introgression, but the more or less spathaceous calyces and the greater extent of purple pigment in its vegetative parts presumably would not.

Selected References

None.

Lower Taxa

None.