The Manual of the Botany of the Northern United States / Including the District East of the Mississippi and North of North Carolina and Tennessee

by Asa Gray

19. Gerardia. Stamens strongly unequal, included.

Tribe VII. EUPHRASIEÆ. Corolla tubular, obviously 2-lipped; the upper lip narrow, erect or arched, enclosing the 4 usually strongly didynamous stamens.

[*] Anther-cells unequal and separated. Capsule many-seeded.

20. Castilleia. Calyx tubular, cleft down the lower, and often also on the upper, side. Upper lip of corolla elongated; the lower short, often very small.

21. Orthocarpus. Calyx tubular-campanulate, 4-cleft. Upper lip of corolla little longer and usually much narrower than the inflated lower one.

[*][*] Anther-cells equal. Capsule many–several-seeded.

22. Schwalbea. Calyx 5-toothed, very oblique, the upper tooth much the smallest.

23. Euphrasia. Calyx 4-cleft. Upper lip of the corolla 2-lobed, and sides folded back. Capsule oblong.

24. Bartsia. Calyx 4-cleft. Upper lip of corolla entire and sides not folded back.

25. Rhinanthus. Calyx inflated, ovate. Capsule orbicular; seeds winged.