7. Pentstemon. Corolla tubular. Sterile stamen about as long as the rest. Seeds wingless.
Tribe IV. GRATIOLEÆ. Corolla tubular, not saccate nor spurred. Capsule 2-valved. Flowers solitary in the axils of bracts or leaves, peduncles naked (or 2-bracteolate in n. 12). Leaves all or the lower ones opposite. No trace of a fifth stamen.
[*] Stamens 4, all anther-bearing and similar.
8. Mimulus. Calyx prismatic, 5-angled, 5-toothed. Corolla elongated.
9. Conobea. Calyx 5-parted, the divisions equal. Corolla short.
10. Herpestis. Calyx 5-parted, unequal, the upper division largest. Corolla short.
11. Limosella. Calyx 5-toothed. Corolla open bell-shaped, 5-cleft, nearly regular. Leaves alternate or fascicled, fleshy. Dwarf aquatic or marsh plant.
[*][*] Anther-bearing stamens 2; usually also a pair of sterile filaments.
12. Gratiola. Calyx 5-parted. Stamens included; the sterile pair short or none.
13. Ilysanthes. Calyx 5-parted. Stamens included; the sterile filaments protruded.