Approximately 300 species of annuals and perennials mainly from the temperate climates of the northern hemisphere, eastern Australia and New Zealand. (For the rest of the southern hemisphere see Gentianella). They are clump-forming to tufted plants, sometimes forming mats or hummocks, with simple leaves in opposite pairs. The flowers have a tubular, sometimes trumpet to cup-shaped base and five (rarely four) spreading or erect lobes linked together by small folds or pleats of tissue which are absent in the closely allied Gentianella. The small seeds are usually flattened and often winged. (In Gentianella they are rounded and never winged). The group of species from eastern Australia and New Zealand are like the South American gentianellas in general appearance, also lacking the pleats between the corolla lobes and having rounded seeds. Local botanists however, consider them distinct enough from Gentianella to merit a separate name, but to date this has not been validly published. For this reason, all the Australian species are somewhat anomalously retained here.
This is a standard and indispensable genus in the alpine gardener's repertoire, most species being small and inhabiting montane to alpine habitats in the wild. Some species, e.g. G. acaulis and its allies. G. septemfida and G. verna var. angulosa are not only beautiful but easily grown in ordinary garden soil that is moderately fertile, does not dry out and receives plenty of sun. Others, notably G. sino-ornata and its Asiatic allies, are just as easy, providing the soil is acid. The Australian and New Zealand species thrive best in gritty, humus-rich soil but are unreliably hardy and often short-lived. Others are less easy, some thriving best in the environment of an alpine house. For these, cultural notes will be found at the end of the species, description. Propagation by seed ideally sown when ripe or as soon afterwards as possible, in a cold frame (packeted seed may take a year or so to germinate). Careful division can be carried out in early spring or immediately after flowering. Cuttings of non-flowering shoots may also be taken in spring or late summer in a cold frame. Plants with prostrate stems can be layered in summer.