FIRST IMPRESSIONS: Amorpha canescens is an upright shrubby perennial with fine textured compound gray-green leaves. In summer, plants are crowned by purple pubescent flower spikes. This durable long lived species originates from a deep taproot and thrives in harsh sunny dry conditions.
HABITAT & HARDINESS: Amorpha canescens ranges from Manitoba and Ontario to Montana and Michigan and south from New Mexico to Louisiana.
Plants are indigenous to dry Blackland prairies, sand prairies, gravel prairies, hill prairies, sandy open woods, limestone glades and oak savannas. This species usually occurs in high quality habitats and is tolerant of prescribed burns.
Hardiness rating is from USDA Zones 2-9.
PLANT DESCRIPTION: Amorpha canescens is an upright to sprawling perennial anchored by a sturdy taproot. The taproot occasionally branches and can extend 4-10’ or more into the soil.
Young stems are light green bearing odd pinnately compound leaves. Each leaf is 4-12” long and consists of up to 50 leaflets each about ½” long. Leaves, stems and flower stalks are covered with white hairs.
From early to mid-summer, plants are topped by 2-6” flower spikes. The tiny plum purple florets have reddish exerted stamens and golden anthers.
After flowering small hairy pods containing 1-2 seed appear.
Plants grow 1-3’ tall with an equal spread.
CULTURAL & MAINTENANCE NEEDS: Amorpha canescens grows best in sunny sites with well drained average to dry soil.
Young plants expend a good bit of energy producing deep roots. As a result, they tend to get off to a slow start. Around the third year when roots are established, the upper half of the plant begins to flourish.
Tolerates light shade, drought, poor soils, loamy, gravelly or clay soils, acid to alkaline pH, moderate salinity and controlled burns.
Foliage is fairly pest resistant. Plants are, however, browsed by deer, rabbits and livestock. Damage by mammalian herbivores can make it difficult to establish young plants.
Excess shade or competition from neighboring plants promotes a sprawling habit and can eventually lead to decline.
LANDSCAPE USES: This is a good choice for a Wildlife Garden, Urban Landscape or Dry Meadow. Plants are also used as Pollinator Plants, Butterfly Host Plants or as part of a Grouping or Mass Planting. Amorpha canescens has Showy Blooms, and can be used for Erosion Control and in Cottage Gardens, Low Maintenance Plantings, Water Wise Landscapes and Perennial Borders
COMPANION & UNDERSTUDY PLANTS: Try pairing with Asclepias tuberosa, Echinacea purpurea, Rudbeckia hirta, Solidago speciosa, and Sorghastrum nutans.
If a substitute is needed, Baptisia australis is another long lived legume with similar flower color and foliage.
TRIVIA: Like other members of the Pea family, Amorpha canescens is a nitrogen-fixing legume. Plants have a symbiotic relationship with the Rhizobium bacteria that allows them to utilize atmospheric nitrogen.
The genus name comes from the Greek amorphous which means “deformed” due to the floret shape. The corolla is atypical for a member of the pea family since it lacks wings and a keel. The specific epithet describes the silvery-gray hairs which look to some like a dusting of lead.
Pollinators including long-tongued bees, short-tongued bees and beneficial wasps flock to the blooms. Plants host caterpillars of Dogface Sulfur butterflies and several moths. Plants are high in protein and palatable to deer, rabbits and livestock.