Smooth herbs with a bitter colourless juice; leaves opposite, sessile, entire, simple, without stipules; flowers regular, perfect, in clusters, axillary or solitary at the ends of the stems; fruit usually a two-valved septicidal many-seeded capsule.
I. Gentian a. (Tourn.) L.
1. G. Macounii. Macoun's Gentian.
2. G. Amarella L. var. acuta. Michx. Northern Gentian.
3. G. propinqua. Richards. Four-patted Gentian.
4. G. arctophila. Alpine Gentian.
5. G. prostrata. Haenke. Dwarf Gentian.
6. G. affinis. Griseb. Large Gentian.
7. G. glauca. Pale Gentian. II. Halenia. Borkh.
1. H. deflexa. (Sm.) Griseb. Spurred Gentian.
III. Menyanthes. (Tourn.) L.
1. M. trifoliata. L. Marsh Buckbean.
Perennial herbs or shrubs, mostly with milky acrid juice; leaves entire, opposite or alternate, without stipules; flowers regular, the lobes of the corolla convolute and often twisted in the bud, calyx free from the two ovaries which are distinct; fruit slender elongated terete seed-pods, seeds often comose.
I. Apocynum. (Tourn.) L.
1. A. androsaemifolium. L. Spreading Dogbane.