| | 1. Calyx lobes ovate, tip obtuse to acute, ± = fruit; leaves petioled if serrate |
| L. uniflorus |
| | 1' Calyx lobes awl-like, tip acuminate to short-awned, generally > fruit; leaves ± sessile if serrate |
| |
| | 2. Leaves generally short-petioled, deeply lobed to cut in lower half; fruit 1–1.5 mm, top rounded |
| L. americanus |
| | 2' Leaves generally subsessile to sessile, serrate; fruit 1.5–2 mm, top ± truncate |
| L. asper
|