Kearney's bluestar is one of the rarest flowering plants in the United States, a federally endangered species with a single confirmed wild population in the Baboquivari Mountains of Pima County, Arizona. When listed under the Endangered Species Act in 1989, the entire global wild population consisted of eight individuals. Conservation propagation has since established nursery-grown stock, and a possible second population may exist just across the border in Sonora, Mexico.
In the wild this species occupies riparian canyons, cycling through seasonal flash flooding and prolonged drought. Threats to natural recruitment include livestock trampling and insect predation on developing seeds, which renders much of the seed crop sterile before maturity. In cultivation it performs best in well-drained, rocky or sandy soil with supplemental irrigation during dry periods and good air movement around the crown. Because wild plants are federally protected, all cultivated stock must originate from nursery propagation.
The pale blue, star-shaped spring flowers typical of the Amsonia genus attract native bees and other pollinators. Growing this plant from nursery-propagated stock supports awareness of endangered desert-riparian flora and contributes directly to recovery efforts for the species.
Phytophthora Root Rot
Wilting despite moist soil, yellowing leaves, stunted growth, and dark, decayed roots and crown tissue. Vines may collapse during hot weather.
Plant in well-draining soil and avoid waterlogging. Remove and destroy affected vines. Improve drainage with raised beds or amended soil and avoid overwatering.
Crown Rot
Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.
Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.