1. Corolla ± cylindrical, the lobes acute, barely if at all spreading; anthers ca. 1.5-3.5 mm long.

L. molle

1. Corolla funnelform or salverform, the lobes (especially if corolla over 10 mm long) usually spreading, not pointed; anthers 0.3-2 mm long.

2. Corollas light to deep yellow, showy, the limb 9-22 (-25) mm broad, much exceeding the calyx; plants with a terminal inflorescence (inflorescence elongates later in season and flowers may then appear ± axillary).

3. Corolla with tube (unexpanded portion) 22-35 mm long and lobes distinctly erose or fringed; leaves narrowly linear, mostly less than 4 mm wide (a few as wide as 6.5 mm); pubescence on stem entirely of closely appressed hairs.

L. incisum

3. Corolla with tube 6-14 mm long and lobes entire (though often undulate); leaves mostly broader; pubescence, at least on stem, all or partly spreading.

4. Calyx lobes 2.2-4.5 (-5) mm long (to 6.5 mm in fruit); pubescence of leaves, stems, and bracts soft, usually not pustulate-based.

L. canescens

4. Calyx lobes (5-) 6-10 (-13) mm long; pubescence largely of very stiff slightly pustulate-based hairs.

L. caroliniense

2. Corolla white to pale yellow or greenish, the limb less than 8 mm broad, barely if at all exceeding the calyx (at most by 1.5-2 (-3) mm); plants with flowers appearing mostly axillary.

5. Largest leaves or bracts 2-4 cm broad; cauline leaves usually 15-20 or even fewer below the inflorescence; pubescence of leaves and stems all or mostly closely appressed.

L. latifolium

5. Largest leaves or bracts (0.5-) 0.7-2 cm broad; cauline leaves at least 25-30 below the inflorescence; pubescence, especially on undersides of leaves, mostly somewhat ascending (raised, not appressed).

L. officinale