Acmispon americanus var. americanus

From Puget Prairie Plants
(Redirected from Lotus unifoliolatus)
  • Scientific Name: Acmispon americanus var. americanus
  • Family: Fabaceae
  • Common Names: American bird's-foot trefoil
  • Synonyms/Misapplications: Lotus purshianus, Lotus unifoliolatus
  • Codon: ACMAME

Photo by Robert L. Carr. Also featured on Main Page


Scientific classification
Kingdom: Plantae
Subkingdom: Viridiplantae
Phylum: Tracheophyta
Subphylum: Spermatophytina
Class: Magnoliopsida
Subclass: Rosanae
Order: Fabales
Family: Fabaceae
Genus: Acmispon Raf.
Species: Acmispon americanus var. americanus (Nutt.) Rydb.



Hairy annual herb to 6 dm tall with axillary, cream to yellow papilionaceous flowers.[2] Stems erect to prostrate.[3] Leaves mostly 3-foliate, upper leaves often becoming simple, stipules minute.[4] Calyx teeth longer than tube; corolla cream to yellowish; stamens 10, diadelphous; ovary simple, superior.[2] Pods with 4-8 seeds, slightly constricted.[3]

Bloom Period

April to September[3]


Across Washington, southern British Columbia to Mexico, inland across North America.[2]


Sandy or rocky soils in forested or open locations.[2]


Hot water treatment if planting by seed. Irrigate one time per month once established.[5]

Photo Gallery


  1. Integrated Taxonomic Information System. Retrieved from
  2. 2.0 2.1 2.2 2.3 Hitchcock, C. L., Cronquist, A., Giblin, D., & Legler, B. et al. (2018). Flora of the Pacific Northwest: an illustrated manual. Seattle: University of Washington Press, p. 128.
  3. 3.0 3.1 3.2 WTU Herbarium, Burke Museum, & University of Washington. Retrieved from
  4. Jepson Herbarium Online Flora. Retrieved from
  5. California Native Plant Society: Calscape. Retrieved from's-Foot-Trefoil)?srchcr=sc5aa1b8aa18112