Argemone is a genus of about 30 species of plants in the poppy family, or Papaveraceae. Those in this genus are commonly known as the prickly poppy. They are so named because of their spiny leaves. The plants tend to grow in sunny areas with little water. Gardeners can grow several species as annuals, for their large white or brightly-colored flowers that generally have orange centers.
Prickly poppies are unusually tolerant of salts in the soil and prefer to grow in sandy, well-drained soil. These types of plants are usually grown from seed and will keep forming colonies once planted. They generally form large clumps that reach up to 4 feet (1.2 m) high. Many have sap that is toxic to animals, including humans. Livestock will not eat these spiny plants, even during periods of drought.
One species of some notoriety is Argemone mexicana, the Mexican poppy. This is one of the species that produces toxic sap. This resin contains several alkaloid compounds. It resembles mustard oil and has, in some cases, contaminated cooking oil, which led to the poisoning of unwitting consumers.
The Mexican poppy grows widely in the United States and in India. Its resin has also been used medicinally. The plant is a perennial that is frequently grown by gardeners as an annual. It has orange or yellow flowers that grow to 6.4 inch (16 cm) wide.
Argemone polyanthemos is another poisonous prickly poppy species. It is dangerous to ingest any part of this plant. In addition, its spines can irritate the skin. The 5-inch (12.5 cm) flowers are white and are the reason the plant is grown. This annual blooms from spring to fall.
Another annual is the white prickly poppy, or Argemone albiflora. This species is very spiny. Its 8-inch (20 cm) wide flowers are white, as indicated by the name. This is another Argemone species with poisonous sap.
The annual rose prickly poppy — Argemone sanguinea — has pink to lavender flowers that can grow to 7 inches (17.5 cm) across. Due to its vivid flowers, the plant has been used in decorations. This species is also poisonous.
There are several desert prickly poppies of note that grow in California. Argemone munita, called the flatbud prickly poppy, grows in the western and eastern parts of the state. It has white flowers that can be up to 3.2 inches (8.2 cm) wide. The plant usually reaches a height of at least 1 ft (0.9 m) tall, and can be grown as an annual or perennial.
Another desert poppy is one that grows in the Mojave Desert. The Mojave prickly poppy, or Argemone corymbosa is a perennial plant that grows up to 26 ft (8 m) tall. Its white flowers can grow up to 6.4 in (16 cm).