Herbs or shrubs, with coloured latex which is yellow (Argemone) or orange-brown (Bocconia). Stipules 0. Leaves alternate, deeply divided or lobed. Flowers actinomorphic, bisexual, usually hypogynous. Sepals 2-3, caducous. Petals 4-6, in two whorls of 2 or 3, free, falling off early. Stamens numerous. Ovary 1-locular with numerous ovules. Fruit a capsule dehiscing by valves or pores.
Barcode of Life Data Systems (BOLD) Stats Specimen Records:817 Specimens with Sequences:994 Specimens with Barcodes:652 Species:199 Species With Barcodes:191 Public Records:596 Public Species:159 Public BINs:0
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.
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. 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 broad circumscription of Papaveraceae in the APG III system includes three taxa that have been separated into different families: the Papaveraceae sensu stricto, the Fumariaceae and the Pteridophyllaceae. Thus the Cronquist system of 1981 recognised the Fumariaceae as a separate family, despite their close phylogenetic relationship to the Papaveraceae sensu stricto. The three former families may be treated as subfamilies. One morphological and molecular study concluded that the former family Pteridophyllaceae has a basal position with a subsequent division into two terminal clades each containing one of the subfamilies Fumarioideae and Papaveroideae, which are clearly monophyletic. A more recent study includes the former Pteridophyllaceae in the Fumarioideae, dividing the Papaveraceae into only two subfamilies.
The internal division of the Fumarioideae shown below follows Lidén (1993), with the exception of the placement of Pteridophyllum. The division of the Papaveroideae follows Hoot et al. (1997). In the latter study, the Eschscholzieae tribe would be the basal clade and sister group to the rest of the subfamily, which is divided into a different terminal clade (Chelidonieae) and into its sister group, formed by the Papavereae and Platystemoneae, whose separation is not based on the data presented by these authors. For discussions of subfamilies, see Carolan et al. (2006) and Blattner & Kadereit (1999).
Lamprocapnos spectabilis, often commonly called by its old name, Dicentra spectabilis.
Pollination is entomophile (basically by flies and wasps and bees, less often by beetles), except in Bocconia and Macleaya. In Papaveroideae, the reward is pollen as there is no nectar. The visual attractant is the petals that are usually brightly coloured and often have basal guides, sometimes the attractant can also be the androecium as the petals do not last long. Some species, mostly those from the arctic and alpine regions, reinforce their attraction with floral fragrance (for example, Papaver alpinum smells of cloves), which in the case of Romneya drugs the insects. The anthers and stigmas mature at the same time, but Bocconia is clearly protogynous, the stigmas emerge from the calyx that encloses them. Autopollination is common and in some cases (for example, Roemeria hybrida) it occurs before the bud opens (cleistogamy). The presence of an aril suggests dispersion of seeds by ants (myrmecochory), once they have been expelled by the fruit. In the case of Bocconia the seeds remain attached to the replums after the capsule’s valves have fallen leaving their brilliant red or orange arils exposed, which attract birds to feed on them, facilitating their dispersal (ornithochory). Seeds that lack an aril appear to be dispersed by the wind (anemochory) for capsules that open, in the other cases they are freed when the fruit decomposes. Many Fumarioideae species have explosive fruits (ballistic), while Rupicapnos and Sarcocapnos species are chasmophytes, growing on rocks, and their fruit’s peduncles and pedicles are geotropic and they lengthen so that the seeds bury into the base of the plant.
The Papaveroideae typically grow in cooler and wooded areas, forming part of the undergrowth. They have adapted to arctic and alpine habitats and to arid, Mediterranean areas, many species are ruderal and segetal (growing in cornfields). Pteridophyllum grows in the undergrowth of woods of needle-leaved trees between 1,000 m and 2,000 m. The Fumarioideae are basically found in open, rocky, alpine landscapes or vertical or overhanging cracks, while some species are ruderal or segetal.
Many of these plants are poisonous. The Mexican Prickly Poppy is poisonous if taken internally and may cause oedema 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.
Hoot, S.B.; Kadereit, J.W.; Blattner, F.R.; Jork, K.B.; Schwarzbach, A.E. & Crane, P.R. (1997). "Data congruence and phylogeny of the Papaveraceae s.l. based on four data sets: atpB and rbcL sequences, trnK restriction sites, and morphological characters". Systematic Botany 22: 575–590. JSTOR2419829.
Lidén, M.; Fukuhara, T.; Rylander, J. & Oxelman, B. (1997). "Phylogeny and classification of Fumariaceae, with emphasis on Dicentra s.l., based on the plastid gene rps16 intron". Plant Systematics and Evolution 206: 411–420.
Wang, W.; Lu, A.-M.; Ren, Y.; Endress, M.E. & Chen, Z.-D. (2009). "Phylogeny and classification of Ranunculales: Evidence from four molecular loci and morphological data". Perspectives in Plant Ecology, Evolution and Systematics 11: 81–110. doi:10.1016/j.ppees.2009.01.001.