Family: Apocynaceae

This is a deciduous, grassy-leaved plant with milky sap, eventually reaching 2-3’ tall and wide, though often much smaller. The leaves are variable from lance-shaped to threadlike. Clusters of fragrant, five-petaled, white flowers with a tinge of blueish lavender are produced from March through May. Follicles follow which are full of corky seeds which have evolved to float in water. Plants form a woody base from which they emerge each spring.

Put in full sun or afternoon shade, avoid reflective heat. Moderate water when established. Provide good drainage. Hardy to -10º F. Cut back dead foliage when plants go dormant.

Many insects visit the flowers. The pollinator is most likely a hawk moth, as suggested by the pale flower color and long floral tube. Little is known about the breeding systems of Amsonia species. It is difficult to do pollination studies because the stamens are enclosed in the corolla tube on short filaments. The conchuela stink bug (Chlorochroa ligata) feed on the seeds. The obscure sap beetle (Conotelus obscurus) live in the seed capsules during their larval stages and feed on petals and pollen as adult beetles.

Amsonia is named for Charles Amson, American physician who lived in Virginia in 1760 and was a friend of prominent physician, botanist and plant collector John Clayton. Grandiflora means large or grand flower.

This plant is imperiled in nature, threatened by ranching, mining, and trampling in public areas. Native to canyons in oak woodlands, 3900-4500 ft., restricted to southern Arizona and northern Sonora.

Photo by Steve Buckley, iNaturalist