South Dakota Native Plant Research
 
Fabaceae : Amorpha nana

Fabaceae : Amorpha nana

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Family Name

Fabaceae

Common Name

Dwarf wild indigo

Description

Amorpha nana is deciduous perennial shrub, which grows 30 cm to 60 cm in height. The stems are branched above, often covered with short hairs when young. The alternate, compound odd-pinnate leaves are 3-10 cm long with 3-10 cm long petioles having associated stipules that are 3-5 mm long. The broadly oblong leaflets are arranged in 6-15 pairs with a single terminal leaflet and are 6-13 mm long by 3-6 mm wide. Dwarf indigo flowers are borne in densely flowered terminal racemes, 3-9 cm long. The dark, purple-colored flowers appear from May to June. The sepals form a short turbinate tube 2-3 mm long with 1-2 mm long triangular lobes. The corolla is composed of petals fused into a tube, 5-6 mm long, with a slender claw, and encloses the stamens and pistil. There are 10 stamens fused at the base and a single pistil. The fruit is a legume, 4.5-5.5 mm long by 2-3 mm wide. This species is commonly found on dry prairies and rocky or sandy hillsides.

Additional Notes

Dwarf Indigo has a deep root system making it drought tolerant and resistant to grazing after it is established for 3-4 years. The sweet-smelling blossoms attract bees and butterflies, and the larvae of the native Silver Spotted Skipper butterfly use the leaves. This species forms nitrogen0fixing nodules, allowing it to grow in poorer soils and improving the soil for other plants in the garden,

Horticulture Notes

Seed Collection: Legumes can be harvested in late summer when the pods begin to dry.
Germination: Seed coats are water impermeable and seeds must be scarified of planted outside in the fall.
Vegetative Propagation:
Soils: Well drained loams or Loamy-sand soils are best.
Light: Full sun
Water: Medium to dry.

Fabaceae : Amorpha nana

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