Papaver

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 numerous, tiny seeds escape with the slightest breeze through the pores of the capsule. 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. The following are lectotypified with their lectotype species: Papaver sect. Argemonidium includes four annual, half-rosette species, P. argemone, P. pavonium, P. apulum, and P. hybridum (Kadereit 1986a). Papaver apulum, P. argemone and P. pavonium occur allopatrically from the Adriatic Sea to the Himalayan range. P. hybridum is distributed widely from the Himalayas to Macaronesian Islands. These species are easily distinguished in petal and capsule characters, but are clearly closely related according to molecular analysis. Argemonidium is a sister group to all other Papaver sections, with characteristic indels. Morphological characters also support this distinction, including the presence of an apical plug in the capsules, long internodes above the basal leaf rosette, bristly capsules and polyporate pollen grains. Carolan et al. (2006) supported Kadereit et al. (1997)’s suggestions that Argemonidium and Roemeria are in fact sister taxa. They share some morphological characters that distinguish them from Papaver, including polyporate pollen grains, and long internodes superior the basal leaf rosette. Previous taxonomies of the Old World clade did include the close relationship between Argemonidium and Roemeria, nor Argemonidium’s distinctness from Papaver s.s. Carolan suggest Argemonidium be elevated to genus status, with Roemeria a sub-genus. Papaver sect. Meconella is widely distributed, with populations spanning central, inner and eastern Asia, Siberia, Scandinavia, northern Greenland, Canada, the Rocky Mountains, and regions of Europe. It has been distinguished from other Papaver sections morphologically by its bristly, valvate capsules, pinnatisect leaves, pale stamen, and white, orange or yellow corolla. Older taxonomies divided Meconella into two groups based on degree of leaf dissection (finely dissected leaves vs. broad leaf lobes). Kadereit (1990) and Kadereit and Sytsma (1992) regarded finely dissected leaves as a derived character, and suggested that Meconella formed a group with Argemonidium as sister to other Papaver sects. Bittkau and Kadereit (2002) demonstrated that for P. alpinum s.l. broad leaf lobes were ancestral. Carolan et al. (2006) resolved Meconopsis as sister to sect. Meconella, forming a sister clade to the rest of Papaver, excluding Argemonidium. Meconella possesses a sessile stigmatic disc, similar to the typical discs of Papaver sect. Papaver., yet differences in the disc and other morphological characters have led to suggestions that this feature may not be homologous. The results of the Carolan et al. (2006) analysis present a major problem to previous taxonomy of the genera Meconopsis, and Papaver. As several species of Meconopsis (excluding M. cambrica) and P. Meconella resolved as a monophyletic group, sister to other Papaver sects., either Meconella must be elevated to genus status, or combined with the Asian species of Meconopsis, as a subgenus of Papaver.