Please try our next iteration of the Michigan Flora Online here. Beginning on February 1, 2023, michiganflora.net will point to this new site.

The new site offers several benefits over the existing website, including real coordinate mapping, giving a clearer view of the density of documentation as well as more precision about plant distributions and their link to landforms. We will also have the ability to update species pages more regularly, both in terms of new collections and as more existing Michigan specimens are georeferenced. In addition, we have a better photo display, and offer indented keys.

Individuals with white flowers may be expected in all the species in which the corolla is ordinarily blue or purplish. Interspecific hybrids occur rarely.

1. Plaits [folds] between the corolla lobes distinctly longer than the lobes, toothed or erose; calyx lobes minutely ciliate.

G. andrewsii

1. Plaits distinctly shorter than the corolla lobes, entire or toothed; calyx lobes smooth, papillose, or ciliate.

2. Stem puberulent, especially on the angles; calyx lobes linear, broader at the very base; corolla open at anthesis.

G. puberulenta

2. Stem glabrous; calyx lobes broadest above the base (or linear in G. linearis and G. rubricaulis); corolla nearly closed at anthesis.

3. Calyx lobes distinctly keeled basally on the underside and in one species also minutely ciliate; apex of plaits between the corolla lobes ± strongly erose or at least bifid; plants only in the southern half of the Lower Peninsula.

4. Leaf blades (at least the upper) (1.7–) 2.7–5 cm broad; calyx lobes and leaves not ciliate; flowers white, marked with greenish.

G. alba

4. Leaf blades less than 2 cm broad; calyx lobes (and at least the involucral leaves) densely ciliate; flowers mostly blue.

G. saponaria

3. Calyx lobes without a keel or cilia (at most minutely papillose or scabrous); apex of plaits between the corolla lobes broadly triangular, terminating in a single off-center tooth (sometimes with a much smaller subsidiary tooth on each side); plants only in the Upper Peninsula and north half of the Lower Peninsula (though farther south in Ontario).

5. Leaves deep green, linear or nearly so, not over 1 cm broad; calyx lobes green throughout, ± exposed by the spreading, narrow involucral leaves.

G. linearis

5. Leaves ± pale green, lanceolate to ovate, at least the larger ones over 1 cm broad; calyx lobes green at most toward apex, usually well concealed by the broad, enveloping involucral leaves.

G. rubricaulis