Bush's Poppy-mallow is a native perennial forb with a limited native range in the U.S. It grows 12 to 18 inches high on stems that partially erect and rambling. Stems are greenish with white spreading hairs. Stems can be multiple from the root.
The leaves are palmately divided into 5 to 7 lobes. The lower more basal leaves have the most divisions and each of the larger lobes has crenelations (big teeth) on the tips of the lobes. These leaves are on long stalks. The stem leaves grade to smaller in size with fewer lobes with fewer teeth. These are on long stalks also. All leaf stalks are hairy and at the base of the leaf stalk is a pair triangular hairy stipules. The vein pattern of the leaf is palmate giving a quilt-like appearance to the bright green upper leaf surface. Blades are up to 5 inches wide, broader than long.
The inflorescence is a single stalked flower rising from a leaf axil along the stem.
The flowers are perfect, 5-parted, on long stems that have fine hair. The corolla has five magenta wedge shaped petals forming a funnel shape up to 2-1/2 inches wide when open. The petals are united at their bases for up to 1/4 the calyx length. In the center of the flower is an ovary of 10 to 20 carpels with styles. Surrounding these, as in most Mallows, are a column of fused stamen filaments. Anthers are yellow. The outside of the calyx is hairy with 5 pointed sepals, not as long as the petals. Beneath the calyx on the flower stalk are 3 linear hairy green bracts, shorter than the sepals.
Seed: Each carpal can produce a single seeded capsule, the seed with a honey-comb like surface. The carpals form a ring when dry and then the capsules burst to release the seeds, which are usually not wind-blown, but fall near the plant. Mature seeds are almost black, shaped like a Nautilus shell with a fairly smooth surface; they are rather heavy - 4,000 to the ounce and need 30 days of cold stratification to break dormancy or sow in the fall to overwinter.
Habitat: Bush's Poppy-mallow grows from a stout thick taproot. It prefers full sun to partial shade with mesic to dry moisture conditions. Well drained soils should be used, avoiding heavy clayey soil. Because of the taproot, plants do not transplant well.
Names: The genus name, Callirhoe covers many plants of the poppy-mallow type and was named after the daughter of a minor Greek river god - Achelous. The species name, bushii, is an honorary for American botanist Benjamin Franklin Bush (1858-1937), who discovered the plant. The author name for the plant classification -‘Fernald’ is for Merritt Lyndon Fernald (1873-1950) American botanist, Harvard Professor, scholar of taxonomy. Several former varieties of other species have now been consolidated into this species - C. involucrata var. bushii and C. papaver var. bushii.
Comparisons: The poppy-mallows have similar flowers. The two closest in comparison to Bush's are C. involucrata, Purple Poppy-mallow, and C. papaver, Woodland Poppy-mallow.
Above: The five petals are fused at their bases. The stamen filaments are fused into a column around the pistils. The outer calyx has 3 small hairy bracts beneath it.
Below: Flowers rise on a long stalk from an upper leaf axil. At the base of each leaf are a pair of triangular shape stipules.
Below: The larger lower leaves have 5 to 7 lobes while the stem leaves have 3 to 5.
Below: 1st photo - The seed head in the form of a flat ring with the seed capsules arranged around the center connection point. 2nd photo - Each seed capsule formed by a carpel contains a single seed.
Below: The dark three-quarter round seeds.
The Poppy-mallows are found throughout the central and eastern U.S. from the Rocky Mountains eastward except the NE area from New York to Maine. About 11 species of Callirhoe are described. Bush's Poppy-mallow is very restricted and rare and due to loss of habitat is now only found in 4 states: Missouri, Arkansas, Nebraska and Oklahoma. It was once in Iowa but apparently now lost.
Bush's Poppy-mallow will grow nicely in Minnesota with correct choice of soils.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"