Common horse gentian has distinctive flowers, its fruits resemble miniature oranges, and it has opposite leaves that are broadly fused together at the bases. The pairs of leaves almost appear as a single leaf with a stem going through it.
Common horse gentian is a perennial herb with an upright, hairy stalk.
The flowers are clustered in the leaf axils on very short stems; they are almost hidden by the green calyx; the petals are reddish brown and tubular, with 5 small lobes.
Blooms May–July.
The leaves are opposite, the middle 3–5 pairs are joined around the stem (perfoliate, each pair looking something like a single leaf with the stem running through it); each leaf is broadly lanceolate, with smooth margins.
The fruits are berries that resemble little oranges; they remain on the stalks through fall.
Similar species: Two other horse gentians grow in Missouri:
- Yellow-flowered horse gentian (Triosteum angustifolium), found in the Ozarks, has narrower leaves that are sessile or have winged stems (its leaves are not perfoliate) and has yellow flowers (sometimes orange to red).
- Red-fruited horse gentian (Triosteum aurantiacum), scattered mostly in the eastern half of the state, is only weakly perfoliate, with the leaves much narrower at the base, and it has orange to red fruits. It can be hard to distinguish from T. perfoliatum.
Height: to 4 feet.
Scattered nearly statewide. Most abundant in the Ozark and Ozark Border divisions.
Habitat and Conservation
Occurs in bottomland forests, rich upland forests, bases and ledges of bluffs, edges of glades, and banks of streams and rivers; also on roadsides and similar disturbed places.
This is the most abundant and widespread horse gentian in our state.
Status
Native Missouri wildflower.
Human Connections
Pennsylvania settlers, and probably others, dried and roasted the ripe fruits of horse gentian and used the product as a coffee substitute, which explains one of the common names for this plant, “wild coffee.”
Despite what the common name implies, this is not a true gentian (in the gentian family, the Gentianaceae). Instead, horse gentian is in the honeysuckle family. What’s going on? The word “horse,” as a plant adjective, implies something large, strong, or coarse. Here are some other examples:
- Horse-chestnut, which is related to buckeyes, and is not in the beech family like edible true chestnuts
- Horse nettle, which is a prickly nightshade, and is not a true nettle (which are in family Urticaceae)
- Horseradish, which, although it's in the same family as radishes, is considerably stronger than the plants we cultivate as radishes.
Ecosystem Connections
This and some other members of the honeysuckle family are larval host plants for the snowberry clearwing, a type of sphinx moth famous for its beelike coloration and for resembling a hummingbird as it visits flowers. The clearwing lays eggs on the horse gentian, and the caterpillars eat the foliage.
Horse gentian flowers are pollinated by bumblebees and other long-tongued insects.
