Our species are all rather similar: somewhat delicate-looking plants with attractive pink-purple corollas falling in the afternoon, very slender linear usually scabrous leaves, and a tiny tap root. This is another hemiparasitic group, with roots attaching to diverse hosts, especially graminoids.
1. Leaves lanceolate or broader, the uppermost often with a pair of basal lobes; stem terete, with stiff retrorse hairs longer than the very short pubescence; calyx pubescent.
1. Leaves narrowly linear (up to 3.5 mm wide), without basal lobes; stem usually angled (not in A. gattingeri), glabrous or antrorse-scabrous; calyx glabrous.
2. Mature pedicels 1–5.5 mm long.
2. Mature pedicels 7–28 (–30) mm long.
3. Calyx tube with at most the longitudinal nerves conspicuous; plants usually blackening when dried; seeds dark brown; widest leaves often 1–3 (–3.5) mm broad.
3. Calyx tube conspicuously reticulate-veined; plants remaining ± green when dried; seeds pale or light brown; widest leaves at most 1 mm broad.
4. Stem nearly or quite terete; corolla with 3 lower lobes pubescent outside; flowers all or mostly on branches, often appearing terminal on these.
4. Stem strongly angled (ridged); corolla with all lobes glabrous outside (though ciliate); flowers usually all or mostly on pedicels in axils of opposite leaves or bracts on the main stem (rarely branched).
All species found in Agalinis
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. July 20, 2019. https://www.michiganflora.net/genus.aspx?id=Agalinis.