| | 1. Fruit pedicel sharply bent near tip; fruit ± round, (6)8–10 mm, wing wide, rays very distinct, vein-like |
| T. radians |
| | 1' Fruit pedicel curved to straight; fruit elliptic to round, < 8 mm, wing narrow to ± wide, rays 0 or ± indistinct, not vein-like |
| |
| | 2. Fruit bowl-shaped, wing strongly curved to flat or concave side; pedicel curved to straight |
| T. conchuliferus |
| | 2' Fruit ± flat, wing flat to ± curved to convex side; pedicel curved |
| |
| | 3. Cauline leaves lobed at base, clasping stem, often sagittate, (ob)lanceolate, lower dentate to shallowly lobed; style included in or exserted from fruit sinus; fruit elliptic to round; wing often perforated |
| T. curvipes |
| | 3' Cauline leaves generally tapered at base, generally not clasping stem, linear, lower ± entire to ± deeply lobed; style generally exserted from fruit sinus; fruit elliptic to obovate; wing perforated or not |
| T. laciniatus
|