Papaveraceae is a family of flowering plants. The family has been universally recognized by taxonomists, and is also known as the "poppy family". It is a cosmopolitan family occurring in temperate and subtropical climates. Most are herbaceous plants, but a few are shrubs and small trees.

The plants are laticiferous. 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 (even as flower nectaries are lacking) (= entomophilous), a few by the wind (= anemophilous). There is a distinct calyx and corolla, except in Macleaya where the corolla is lacking. The flowers are medium-sized or large and they look spectacular. The terminal flowers solitary in most 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 alternate with the petals, the inner one opposite. The gynoecium consists of a compound pistil with 2 to 100 carpels. The ovary is superior and 1-locular. The ovary is without a footstalk (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), or 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.

These plants almost all contain alkaloids. Many are poisonous. The Mexican Prickly Poppy (pictured above) is poisonous if taken internally and may cause edema and glaucoma. Even if an animal, such as a goat, should persist in grazing on this plant, not only will the animal suffer but so will those who drink its milk, because the poisons are passed along in the milk.

Taxonomy

The APG II system (2003; unchanged from the APG system of 1998) places the family in the order Ranunculales, in the clade eudicots. However, APG does provide for the option to segregate two families, as optional segregate. Thus, there are two possible circumscriptions:

• Papaveraceae sensu lato, including the plants that would otherwise form the families Fumariaceae and Pteridophyllaceae.
• Papaveraceae sensu stricto, excluding these plants.

The family sensu stricto conforms to the family as recognised by the Cronquist system, of 1981 (Cronquist recognised Fumariaceae as separate). This comprises about 26 genera and about 250 species. The description given above applies to the family in this narrow sense. Genera in Papaveraceae sensu stricto

• Arctomecon
• Argemone : Prickly Poppies
• Bocconia
• Canbya
• Chelidonium
• Dendromecon : Bush Poppies
• Dicranostigma
• Eomecon
• Eschscholzia
• Glaucium
• Hunnemannia : Mexican Poppies
• Hylomecon
• Macleaya : Plume Poppies
• Meconella
• Meconopsis : Blue Poppies
• Papaver
• Platystemon : Creamcups
• Platystigma
• Roemeria
• Romneya
• Sanguinaria : Bloodroot
• Stylomecon
• Stylophorum

Cultivation and symbolism

The family is well loved for the striking flowers known as poppy, with several species grown as ornamental plants, such as California Poppy (Eschscholtzia californica), the California state flower. The common poppy or corn poppy (Papaver rhoeas) is still worn in remembrance of World War I (see also In Flanders Fields). The family also contains the Opium Poppy (Papaver somniferum), which is the source of opium and opiates, as well as most of the poppy seeds used in cooking and baking.

External links

• Papaveraceae in Topwalks
• Papaveraceae [sensu stricto] in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants
• Papaveraceae [sensu lato] in the Flora of North America
• The position adopted by J.L.Reveal
• NCBI Taxonomy Browser [sensu stricto]
• links at CSDL
• Family Papaveraceae Flowers in Israel