the shrub with clouds of butterflies

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PRAIRIE ACACIA
Acaciella angustissima
FABACEAE

  • regular TO MODERATE WATER (TERRACE TO BOTTOM ZONE)

  • FULL TO PART SUN

  • HARDY TO LOW 10º F

  • USUALLY 3X3 FEET BUT GETS BIGGER IN WELL WATERED SITUATIONS. EASY TO PRUNE DOWN

  • CREAM-COLORED FLOWERS IN WARM WEATHER, ESPECIALLY IN THE LATE SUMMER TO FALL

  • LARVAL HOST TO many butterflies and moths

  • NECTAR SOURCE FOR BUTTERFLIES, MOTHS, BEES, AND HUMMINGBIRDS

  • EASY TO GROW. May freeze to ground but regrows rapidly.

One of our favorite places to go is along the bottom of the Huachuca mountains, right on the border on the road that goes to the Coronado National Memorial.

The terrain is mostly desert grassland, with native oaks and mesquites. Along the road (Montezuma Canyon Road) are vast expanses of prairie acacia (Acaciella angustisimma). Old timers may remember this species as Acacia angustissima.

In those summer monsoon days we’ve observed clouds of various species of butterflies gathering nectar from their cream-colored, puffball flowers. And not just the butterflies take advantage of this nectar, so do bees, and other nectar-loving insects.

Prairie acacia is also a larval food plant for a mind-boggling number of butterflies and moths. Several sulfurs, skippers, and blues use this species as a larval food, as does the gorgeous saturnid moth Sphingicampa raspa.

Plant in full sun and give moderate water. In frost-free spots this plant can actually become like a tall shrub or tree (there are a few plants at the Arizona Sonora Desert Museum like this). Most of the time they are small shrubs that send up arching stems, and sucker out, usually about 3 feet tall and wide. They will most often go dormant or freeze back in winter, and reemerge in spring. Cut back damaged growth after the threat of frost is over.

Sphingicampa raspa  , known generally as the squirreltail fescue, uses prairie acacia as a larval food plant.

Sphingicampa raspa, known generally as the squirreltail fescue, uses prairie acacia as a larval food plant.

Katherine Gierlach