Herbs, shrubs or trees, with opposite or alternate exstipulate leaves, and perfect mostly complete and irregular flowers (corolla wanting in one species of Synthyris). Calyx inferior, persistent, 4-5-toothed, -cleft, or -divided, or sometimes split on the lower side, or on both sides, the lobes or segments valvate, imbricate or distinct in the bud. Corolla gamopetalous, the limb 2- lipped, or nearly regular. Stamens 2, 4 or 5, didynamous, or nearly equal, inserted on the corolla and alternate with its lobes; anthers 2-celled, the sacs equal, or unequal, or sometimes confluent into one. Disk present or obsolete. Pistil 1, entire or 2-lobed; ovary superior, 2-celled, or rarely 1-celled; ovules mostly numerous, rarely few, anatropous or amphitropous, borne on axile placentae; style slender, simple; stigma entire, 2-lobed or 2-lamellate. Fruit mostly capsular and septicidally or loculicidally dehiscent. Seeds mostly numerous, the testa reticulated, pitted, striate, ribbed, or nearly smooth; endosperm fleshy; embryo small, straight or slightly curved; cotyledons little broader than the radicle.

About 165 genera and 2700 species, widely distributed, most abundant in temperate regions. 1. Anther-bearing stamens 5; corolla rotate; leaves alternate. (Verbasceae.)

1. Verbascum.

2. Anther-bearing stamens 2 or 4; leaves opposite, verticillate or alternate.

* Corolla spurred, saccate or gibbous on the lower side at the base. (Antirrhineae.) Corolla spurred at the base.

Leaves palmately 3-5-veined.

2. Cymbalaria.

Leaves pinnately veined.

Flowers solitary in the axils.

Throat of the corolla closed by the palate; leaves broad.

3. Kickxia.

Throat of the corolla not closed by the palate; leaves narrow.

4. Chaenorrhinum.

Flowers in terminal racemes.

5. Linaria.

Corolla saccate or gibous at the base.

6. Antirrhinum.

** Corolla neither spurred, saccate nor gibbous on the lower side.

† Anther-bearing stamens 4, the fifth sterile or rudimentary. (Cheloneae.) Sterile stamen a scale adnate to the upper side of the corolla.

7. Scrophularia.

Sterile stamen elongated, longer or shorter than the others. Corolla tubular, 2-lipped, the lobes of the lower lip flat. Sterile stamens shorter than the others: seeds winged.

8. Chelone.

Sterile stamen about equalling the others; seeds wingless.

9. Pentstemon.

Corolla 2-cleft, declined; middle lobe of the lower lip conduplicate.

10. Collinsia.

†† Stamens 4, all anther-bearing, or 2 sterile, or 2 only. a. Stamens 4, all anther-bearing; large Asiatic tree. (Paulownieae.)

11. Paulownia.

b. Stamens 4, all anther-bearing; herbs; corolla 2-lipped; stamens not enclosed in upper lip of corolla. (Mimuleae.)

Calyx prismatic, 5-angled, 5-toothed.

12. Mimulus.

Calyx 5-parted, not prismatic.

Calyx-segments equal; leaves pinnatifid in our species.

13. Conobea.

Calyx-segments unequal, the upper one the largest. Corolla nearly regular, about equally 5-lobed.

14. Bramia.

Corolla manifestly 2-lipped.

Leaves palmately nerved; flower with an hypogynous disk.

15. Hydrotrida.

Leaves pinnately veined; no hypogynous disk.

16. Mecardonia.

C. Stamens 4, 2 anther-bearing and 2 sterile, or 2 only; corolla obviously 2-lipped. (Gratioleae.)

Calyx 5-parted; upper lip of corolla present. Sterile filaments short or none.

Anther-sacs transverse, separated.

17. Gratiola.

Anther-sacs parallel, contiguous.

18. Sophrononthe.

Sterile filaments slender, 2-lobed.

19. Ilysanthes.

Calyx 4-toothed; upper lip of corolla obsolete; low mud plant.

20. Micranthemum.

d. Stamens 4, all anther-bearing; corolla nearly regular; flowers on scapes. (Limoselleae.)

21. Ltmosella.

e. Stamens 2 only (rarely 4 in Synthyris); corolla rotate, salvertorm, tubular, or none. (Veroniceae.) Leaves alternate; flowers spicate; corolla 2-3-lobed or none.

22. Synthyris.

Leaves, at least the lower, opposite or verticillate; corolla 4-lobed.

Corolla rotate or salverform; capsule obcordate or emarginate, compressed.

23. Veronica.

Corolla tubular-funnelform; capsule ovoid, not compressed.

24. Leptandra.

f. Stamens 4, all anther-bearing; corolla campanulate, salverform or funnelform, scarcely 2-lipped. Leaves alternate: flowers in 1-sided racemes. (Digitaleae.)

25. Digitalis.

Leaves, at least the lower, opposite. (Buchnereae.) Corolla salverform; flowers in a long spike.

26. Buchnera.

Corolla campanulate or funnelform.

Stamens nearly equal; calyx-lobes as long as the tube.

27. Afzelia.

Key to Genera.

Stamens strongly didynamous, unequal; calyx-teeth shorter than the tube. Anthers awned at the base; corolla yellow.

28. Dasystoma.

Anthers awnless; corolla purple, pink or rarely white.

Anthers all alike: flowers pedicelled; leaves not auricled.

29. Agalinis.

Anthers of the shorter stamens smaller; leaves auricled at base.

30. Otophylla.

g. Stamens 4, all anther-bearing, ascending under the upper lip of the corolla. (Euphrasieae.) Ovules several or numerous; capsule many-seeded.

Anther-sacs dissimilar, the inner one pendulous by its apex; leaves mostly alternate. Upper lip of the corolla much longer than the lower.

31. Castilleja.

Upper lip of the corolla scarcely longer than the lower.

32. Orthocarpus.

Anther-sacs similar and parallel; leaves mostly opposite. Calyx 2-bracteolate at the base, oblique, 5-toothed.

33. Schwalbea.

Calyx not bracteolate, 4-5-toothed, or cleft or split.

Upper lip of the corolla 2-lobed, its margins recurved; calyx 4-cleft.

34. Euphrasia.

Margins of the upper lip of the corolla not recurved.

Calyx scarcely or not at all inflated in fruit; galea entire. Calyx 4-toothed or 4-cleft; capsule straight. Seeds spreading, numerous.

35. Bartsia.

Seeds pendulous, few.

36. Odontites.

Calyx split on the lower side or on both sides; capsule oblique. Galea short-beaked or beakless.

37. Pedicularis.

Galea filiform-beaked.

38. Elephantella.

Calyx ovoid, much inflated and veiny in fruit.

39. Rhtnanthus.

Ovules only 1 or 2 in each cell of the ovary; capsule 1-4-seeded; leaves opposite.

40. Melampyrum.