Alkali cleomella (Cleomella plocasperma) flowers from May through October, a long blooming season. In June these specimens were photographed in the alkali flats along Highway 299 east of Cedarville CA (Modoc County) near the California/Nevada border.
Also commonly called twisted cleomella or alkali stinkweed, this annual native grows in wet alkaline soils, greasewood flats and near thermal springs in Oregon, California, Nevada, Idaho, Utah and Arizona. It is considered a plant of the Great Basin and the Mojave Desert.
The hairless, smooth alkali cleomella stem is erect and divides distally into several upright branches. The sparse leaves have entire margins and are divided into three narrow leaflets. The leaves nearer the stem top are often smaller and not divided.
The inflorescence is a raceme (unbranched with the flowers maturing from the bottom up) of yellow flowers at the top of the stem. Alkali cleomella flowers have four greenish sepals, four yellow petals and six long, yellow stamens.
The fruits are lobed capsules that hang at the tip of the remaining flower receptacle (top of the flower stalk to which the flower parts are attached). Each alkali cleomella fruit contains 2 to 4 silver grey seeds with brownish or black mottling.
The genus name, Cleomella, is a diminutive of “cleome”, an ancient name for a mustard-like plant. The Greek words “plokos” (a lock of hair, curl or wreath) and “sperma” (seed) form the species name, plocasperma. Perhaps the species name refers to the wreath-like capsule remnant which remains on the plant.