The gentian family
Gentianaceae is the bitter family. Its roots flavor a shelf of aperitifs and digestifs, its alpine members produce one of the few true blues in the plant world, and it sits next door to the coffee family with one clear character separating them.
around 100 genera
roughly 1,700 species
Worldwide, with a strong presence on mountains and in the arctic
Everything in this guide that belongs to Gentianaceae
Gentian root is the reference standard for bitterness. The compound responsible, amarogentin, is among the most bitter substances known from any source, and it remains detectable on the tongue at dilutions where almost nothing else registers at all. The name translates roughly as bitter gentian, which is about as blunt as chemical naming gets.
That is why the family is in a great many bottles. Gentian root is the backbone of aromatic bitters, of several French and Italian aperitifs, and of the old category of medicinal tonics, where the point of the bitterness was that it provoked appetite and digestion. The plant is not making it for anybody's aperitif; it is making it so that grazing animals on a mountain leave it alone.
The family name honors Gentius, an Illyrian king of the second century BC credited with discovering the root's use. And gentian violet, the dye in the antiseptic, has nothing whatever to do with these plants. It was named for the color.
Look at a gentian bud and the corolla is not simply closed, it is wound. The lobes overlap in one consistent direction like the blades of a camera shutter, a pattern botanists call contorted, and in this family it is pronounced enough to be a field character. Between the main lobes many species carry small extra pleats, so the opened flower has a fringe or a web between each pair of points.
The winding is not only a packing solution. A great many gentians close their flowers again, and do it repeatedly: at dusk, and in cold, and when rain arrives. A flower that can shut protects its pollen from being washed out or chilled, which matters enormously to a plant flowering at altitude where the weather turns within the hour. Some alpine species will open and close many times over the life of one flower.
Gentianaceae sits in the same order as the coffee and gardenia family, and the two share a good deal: leaves in opposite pairs, undivided, with a corolla fused into a tube. On a leafy stem they can look much alike.
One character settles it. The coffee family carries stipules that fuse across the stem into a continuous collar at every node. Gentians have no stipules at all, so the stem between the leaf pairs is clean and bare. Ring present, coffee family; nothing there, gentian family. It is a good illustration of how classification actually works, since the thing that separates two large groups is often small, consistent and nothing to do with what the flower looks like.
The heart of this family is high and cold. Alpine gentians are the plants that produce that near impossible saturated blue on European mountains, low cushions with flowers far too large for them, and they are notoriously unwilling to grow anywhere they consider soft. Others reach the arctic, and a few climb far up the Himalaya and the Andes.
Against that background the family's contribution to the flower trade is an oddity, because it is not alpine at all. It came off the open grassland of the southern Great Plains, a plant of hot summers and thin limestone soils, and the wild version is a modest thing with a few purple cups on a thin stem. Everything else in the family that reaches a shop arrives as a pot plant or a bottle.