At least 125 species and probably double this number of annuals, biennials and perennials from the temperate regions of both hemispheres. They are essentially like Gentiana and have been included in that genus. The primary distinguishing feature is a small one, the absence of small pleats or lobes of tissue between the actual petal lobes. Ancillary differences are plants mainly annual or biennial and a branched inflorescence bearing several flowers, but there are many exceptions. According to South American botanists, most of the Andean gentians belong in Gentianella. At the time of writing, this change over has been only partially carried out. According to botanical rules those species still waiting to be officially transferred from Gentiana to Gentianella should be retained as Gentiana when mentioned in any new literature. For a horticulturally biased encyclopaedia this is an absurd situation and a compromise has been adopted. All the chosen species still waiting to be officially redesignated are listed here and marked with a f- Least known of all the gentianellas are the 200 or so species from South America, many of these from high puna or paramo moorland, especially in Peru. They form a very distinctive group, covering annuals, biennials, short and long-lived perennials, some of the latter being woody-based. The range of flower colour is unparalleled elsewhere in the world, covering green, brown, purple, yellow, blue, pink, orange, crimson, scarlet and white, with some bi- and tricolours.
The northern hemisphere gentianellas, mainly because they are annuals or biennials, are seldom grown anywhere in the garden, but some of them are well worth a try and should thrive in most well drained soils, tolerating lime. The South Americans are largely untried, but as a generalisation, a gritty, humusy moist but well drained, neutral to acid rooting medium seems likely to yield the best results. Habitat notes at the end of each species, description should indicate any advantageous modification of this recommendation. Most will need alpine house conditions. All gentianellas need good light. Propagation by seed when ripe or as soon after as possible, in a cold frame. Some of the northern hemisphere annuals and biennials will self-sow when happily situated, and some perennials can be increased by late spring to summer cuttings or spring division.