Papaver pəˈpeɪvər is a genus of 70–100 species of frost-tolerant annuals, biennials, and perennials native to temperate and cold regions of Eurasia, Africa and North America. It is the type genus of the poppy family, Papaveraceae.
The flowers have two sepals that fall off as the bud opens, and four (or up to six) petals in red, pink, orange, yellow, or lilac. There are many stamens in several whorls around a compound pistil, which results from the fusion of carpels. The stigmas are visible on top of the capsule, and the number of stigmas corresponds to the number of fused carpels.
The ovary later develops into a dehiscing capsule, capped by the dried stigmas. The opened capsule scatters its numerous, tiny seeds as air movement shakes it, due to the long stem.
The typical Papaver gynoecium is superior (the flower is hypogynous) with a globular ovary. The style is characteristically absent for the type species opium poppy, and several others, although those with a style do exist. The sessile plate-like stigmata lies on top of the ovary. Pollen-receptive surfaces. The characteristic fruit type of Papaver is the unilocular capsule. The stigmatic disc rests on top of the capsule, and beneath it are dehiscent pores or valves.
Divided into a number of sections by Kiger (1973, 1985), the following are lectotypified with their lectotype species. Subsequent cladistic classification by Carolan et al. (2006) suggested Papaver was not monophyletic.
Clade 1. P. sect. Meconella, Meconopsis
Clade 2. P. sect. Carinatae, P. sect. Meconidium, P. sect. Oxytona, P. sect. Papaver, P. sect. Pilosa, P. sect. Pseudopilosa, P. cambrica, P. sect. Californicum, P. sect. Horrida and P. sect. Rhoeadium
Clade 3. P. sect. Argemonidium, Roemeria refracta
The following are lectotypified with their lectotype species:
P. sect. Carinatae (P. macrostomum Boiss. & Huet)
P. sect. Oxytona (P. orientale L.)
P. sect. Macrantha (P. orientale L.) - superfluous
P. sect. Calomecon (Calomecon orientale)
Papaver sect. Argemonidium includes four annual, half-rosette species, P.