Forming large populations in favorable years, the showy flowers of this annual plant superficially resemble the California poppy. Orange caltrop grows 2–3 feet tall, some times more, and its several branches are quite hairy. It is inclined to spread and is often seen in clumps 2–5 feet across. Leaves are opposite and compound, with 5–10 pairs of leaflets about 1 inch long on each side of the midrib, like the feather of a bird. It is a favorite bird food, especially liked by doves. The flowers, often 2 1/2 inches in diameter, have 5 petals, 5 sepals, and 10 stamens. They are orange in color with dark-vermillion centers.
These are not Poppies, and they are not closely related, but the resemblance is there and large patches provide a display as brilliant and spectacular as those of California Poppies (Eschscholtzia californica). This is one of the most handsome wildflowers in the Southwest, frequent along roadsides. There are several other Kallstroemica species that can be recognized by the opposite, pinnately compound leaves on trailing stems. They have corollas only about 1/2 (1.3 cm) wide. All species are Southwestern. One, Small-flowered Carpetweed (K. parviflora), has orange flowers, and a beak on the fruit that is longer than the round body. Two have yellow flowers and short beaks. On Hairy Carpetweed (K. hirsutissima) sepals do not drop off, and the base of the fruits beak is bristly-hairy. California Carpetweed (K. californica) has sepals that usually drop off after the flower opens, and has no hairs, or only small ones at the base of the beak.
Find seed sources for this species at the Native Seed Network.