Names
Scientific Name: Senna bauhinioides
Synonym: Cassia bauhinioides var. arizonica
Common Names: Twinleaf senna, desert senna, hoja sen, rosamaria
Characteristics
Duration: Perennial
Growth Habit: Subshrub, herb/forb
Arizona Native Status: Native
Habitat: Desert, arid grasslands, pinyon juniper woodlands
Flower Color: yellow
Flowering Season: Spring, summer
Height: up to 2 feet
Description: A small plant with few stems ending in open clusters of 1-3 bilaterally symmetrical, yellow flowers. The flowers are up to 1 inch wide with five crimped-edge petals on short stalks. Foliage is fuzzy, grayish-green with only 2 leaflets (compare with Senna coveseii’s 4 or 6 leaflets). Leaves are shed during dry seasons.
Special Characteristics
Senna is “buzz-pollinated” by carpenter bees and bumblebees. Each anther has a tiny pore at one end and bees hang upside down on the flower so that the anther pores hang downward. The bee vibrates its wing muscles, making a buzzing sound, and the pollen is shaken out where it is caught by the bee’s fine hairs.
Classification
Order: Fabales
Family: Fabaceae
SOURCES:
University of Austin, Lady Bird Johnson wildflower center
wildflower.org/plants/result.php?id_plant=SEBA3
Yavapai County Native and Naturalized Plants (Cooperative Extension) prescottnatives.com/SpeciesDetailForb.php?genus=Senna&species=bauhinioides
Phillips, S. J. and P. W. Comus. 2000. A Natural History of the Sonoran Desert. Tucson: Arizona-Sonora Desert Museum Press.
