Approximately 400 species of deciduous and evergreen perennials mainly from the northern hemisphere with one species in southern South America. Most have basal leaves in rosettes. A few form cushions, e.g. P. allionii, some others have elongated rhizomes and develop into colonies e.g. P. sieboldii, and fewer still produce above ground stems and are almost subshrubby e.g. P. marginata. The majority of species have simple leaves with or without short stalks and teeth but many have lobulate or even fully lobed leaves, e.g. P. pinnatifida.The petals are fused into a tube with five spreading petal lobes often shallowly to deeply notched or lobed at the tips. 90% of species are sexually dimorphic, producing either pin-eyed or thrum-eyed flowers. (See glossary). Seed-set is enhanced when crosses  between the two morphs ('legitimate') are made.

The species are classified into 36 sections:

Sphondylia

Auricula, Cuneifolia, Parryi, Suffrutescens

Primula

Auganthus, Monocarpicae, Obconicolisteri, Malvacea, Pycnoloba, Reinii, Cortusoides, Bullatae, Dryadifolia, Carolinella

Pinnatae

Chartacea, Davidii, Petiolares, Crystallophlomis, Cordifoliae, Fedtschenkoana, Proliferae, Sikkimensis, Oreophlomis, Armerina, Glabra, Yunnanensis, Aleuritia, Pulchella, Minutissimae, Denticulata, Capitatae, Muscarioides, Soldanelloides

Uses

Several primulas are indispensable rock garden plants e.g. P. auricula, P. marginata and their hybrids, P. frondosa, P. elatior, P. denticulata and many others are suitable. The primose, P. vulgaris and cowslip P. veris make charming subjects for naturalisation.  The majority of species require a well-drained but moist, humus-rich soil and protection from hot sun and dessication. Some species prefer very wet sites, notably members of sections Proliferae, Sikkimensis and P. rosea. Members of section Cortusoides are woodlanders. P. allionii and P. henrici are classic subjects for the alpine house. Many of the Asiatic primulas require cool growing conditions (especially section Petiolares) and tend to be short-lived. Propagation of all species by seed, stored in the fridge and sown in winter and kept outside. Clump-forming species can also be divided when dormant or after flowering, but most are very susceptible to cucumber-mosaic virus and are strongest when grown from seed..

a, P. edelbergii; b, P. gaubeana; c, P. verticillata;

a, P. hirsuta; b, P. integrifolia; c, P. minima; d, P. palinuri;

a, P. kisoana; b, P. megasaefolia; c, P. palmata; d, P. parryi; e, P. polyneura;

a, P. bhutanica; b, P. gracilipes; c, P. irregularis; d, P. sonchifolia;

a, P. longipes; b, P. macrophylla; c, P. secundiflora; d, P. tangutica; e, P. tibetica;

a, P. algida; b, P. frondosa; c, P. gemmifera; d, P. muscoides; e, P. primulina; f, P. scotica; g, P. tenuiloba;

a, P. capitata; b, P. pinnatifida; c, P. sapphirina; d, P. sherrifae; e, P. soldanelloides; f, P. wigramiana;