Overview
Acmispon americanus is a slender summer annual in the pea family (Fabaceae), formerly placed in the genus Lotus, growing 4-24 inches (10-60 cm) tall on thin, often reddish, branching stems. The leaves are compound with three narrow leaflets, sparsely covered in soft hairs. Small pea-type flowers appear singly in the leaf axils on short stalks, each 0.2-0.3 inch (5-8 mm) long, white to pale pink and often veined or tinged with red. As a legume, it hosts nitrogen-fixing bacteria in root nodules and adds nitrogen to the soil it grows in. After bloom the flowers form straight, slender seed pods that split to scatter seed. A. americanus germinates in spring, flowers through summer, and dies with the first frosts, completing its cycle in one season. It grows on dry slopes, open woodland, roadsides, grasslands, and recently disturbed or burned ground across much of North America, often as an early colonizer. Being a small, short-lived annual, it adds little lasting structure and can disappear from a site once shading perennials return.
Native Range
Native across much of North America, from British Columbia and the western United States east to the Great Plains and parts of the East, and south into Mexico. It grows on dry open slopes, grasslands, roadsides, forest clearings, and disturbed or burned ground.Suggested Uses
Used in habitat restoration, erosion control, and reseeding of burned or disturbed land, where it establishes quickly and enriches the soil with nitrogen. It appears in informal native and wildflower plantings. Its flowers are visited by small native bees, and its foliage is browsed by wildlife.How to Identify
Appearance
Size & Dimensions
Height4" - 2'
Width/Spread4" - 1'
Bloom Information
Flowers from late spring through summer, roughly May to September, opening a few at a time in the leaf axils over many weeks. Bloom continues longest where summer moisture persists. Flowering ends as the plant dries and sets seed in late summer or fall.
Detailed Descriptions
Flower Description
white to pale pinkFoliage Description
greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Water Needs
Drought Tolerance
Drought tolerant when established
Care & Maintenance
Care Guide
Acmispon americanus grows in full sun on dry, well-drained sandy, loamy, or rocky soils of low fertility and a pH near 6.0 to 7.5. As a nitrogen-fixing legume it needs no added fertilizer and grows on poor ground where other plants struggle. It is drought tolerant and completes its life cycle on natural rainfall in most of its range. The plant reseeds and reappears year to year where soil is disturbed. It needs no irrigation once seedlings are established. Growth is quickest with spring moisture, followed by summer flowering and seed set.Pruning
No pruning is needed for this annual. Plants can be pulled or cut at the end of the season to limit reseeding. Leaving seed pods to ripen allows the plant to return the following year.Toxicity
Non-toxicPlanting Guide
Planting Methods & Timing
Planting Method
direct sow
Plant Spacing
6 inches
