Papaveraceae

The Papaveraceae are an economically important family of about 42 genera and approximately 775 known species of flowering plants in the order Ranunculales, informally known as the poppy family. The family is cosmopolitan, occurring in temperate and subtropical climates (mostly in the northern hemisphere), but almost unknown in the tropics. Most are herbaceous plants, but a few are shrubs and small trees. The family currently includes two groups that have been considered to be separate families: Fumariaceae and Pteridophyllaceae. The plants may be annual, biennial, or perennial. Usually herbaceous, a few species form shrubs or evergreen trees. They are lactiferous, producing latex, which may be milky or watery, coloured or plain. All parts contain a well-developed duct system (these ducts are called 'laticifers'), producing a milky latex, a watery white, yellow or red juice. The simple leaves are alternate or sometimes whorled. They have petioles and are not enclosed by a sheath. The leaves are usually lobed or pinnatifid (i.e. consisting of several not entirely separate leaflets), or much divided. There are no stipules. The plants are hermaphroditic and are pollinated mostly by insects (entomophilous); flower nectaries are lacking. A few are wind pollinated (anemophilous). There is a distinct calyx and corolla, except in Macleaya where the corolla is lacking. The flowers are medium-sized or large. The terminal flowers are solitary in many species. In others the terminal inflorescence is cymose or racemose. The flowers are odourless and regular. There are many stamens, mostly 16 to 60, arranged in two separate whorls, the outer one with stamens alternating with petals, the inner one opposite, or numerous in the subfamily Papaveroideae.:86 The gynoecium consists of a compound pistil with 2 to 100 carpels. The ovary is superior and unilocular. The ovary is either stemless (sessile) or on a short stem (stipitate). The non-fleshy fruit is usually a capsule, breaking open at maturity to release the seeds through pores (poricidal), through the partitions between the cells (septicidal), or by means of valves (valvular). The numerous seeds are small. Their nutritive tissue (endosperm) is oily and farinose. The fruit of Platystemon is a schizocarp. The basic chromosome number, x, is 6, 7, 8, 9, 10 and 11, up to 2n = 84 (dodecaploidy) in species of Papaver, Argemone and Meconopsis. The APG III system (2009; unchanged from the APG II system of 2003 and the APG system of 1998) places the family in the order Ranunculales, in the clade eudicots. The Papaveraceae differ from the rest of the Ranunculales in some important characteristics but they share others such as the presence of isoquinoline-derived alkaloids. Based on molecular and morphological data, the family forms a clade with the families Lardizabalaceae, Circaeasteraceae, Menispermaceae, Berberidaceae and Ranunculaceae.