Chile Trefoil

Chile Trefoil © DSchiel

Chilean Trefoil, Chilean Bird’s-foot Trefoil
Acmispon wrangelianus

Description (Jepson,

  • Eudicotyledon
    • Eudicots are a major lineage of flowering plants; see family for general characteristics
  • Pea Family (Fabaceae)
  • Annual herb
    • Generally ground-hugging (prostrate) and spreading
  • Leaves
    • Compound (divided into leaflets) and alternate (1 leaf at each junction with stem)
    • Usually 4 leaflets, roughly egg-shaped
      • Slightly hairy and fleshy
      • Asymmetrically positioned along the stem
  • Flowers
    • Inflorescence (flower arrangement) is a single yellow flower in the leaf axil (branching point), which reddens with age
    • Characteristic Pea family flower is bilaterally-symmetric, with a banner, wings, and keel
    • Ovary superior (above the attachment of other flower parts)
  • Fruit is a slender legume (a single-chambered seed pod that opens along 2 seams) with a curved beak (narrow prolonged tip)
  • Height to 6 in., spreading to 1 ft.


  • Native to California
    • Common on coastal bluffs, chaparral, grasslands, and disturbed areas
    • See Calflora for statewide observations of this plant
  • Outside California, grows in Oregon and Nevada
  • Grows at elevations to 4,900 ft.

Uses (San Mateo County Parks prohibits removal of any natural material)

  • Wildlife
    • Seeds eaten many animals, including birds, mammals, and ants

Name Derivation

  • Acmispon (ak-MIS-pon) – from the Greek acme, a ”point” or “edge,” referring to the hook-tipped fruit
  • wrangelianus (ran-gel-ee-AY-nus) – named for Ferdinand Petrovich von Wrangell (1796-1870), Russian naval officer and arctic explorer
  • Chile trefoil – This plant is not from Chile, but early travelers to California often sailed around the tip of South America and may have seen a similar trefoil in Chile, which also has a Mediterranean climate
    • Trefoil – from the Latin tres, “three” + folium “leaf,” a common name applied to many plants in the Pea family, especially those in the genus Trifolium, also known as clovers
      • In spite of its name, chile trefoil has leaflets of four


  • Like almost all members of its family, Chile trefoil fixes nitrogen; see Pea family for more details
  • Flowers change color, fading to oranges and reds
    • May be indicating to pollinators whether a specific flower is worth visiting for nectar
    • Flowers from more than 70 plant families use color changes to direct pollinators (Weiss 1991)
  • Small-size, thickness, and hairiness of the leaflets are adaptations to control water loss
  • Taxonomists recently reclassified Chile trefoil, along with other North American plants formerly in the genus Lotus
    • DNA analysis showed that New World Lotus species were distinct from Old World species
      • Native plants at Edgewood previously in the genus Lotus are now in the genus Acmispon
      • Non-native bird’s foot trefoil (Lotus corniculatus) is the only remaining Edgewood plant in the genus Lotus

ID Tips

  • May be confused with the 4 other trefoils at Edgewood
    • Native short-podded trefoil (Acmispon brachycarpus), American trefoil (Acmispon americanus var. americanus), and small-flowered trefoil (Acmispon parviflorus), as well as non-native bird’s foot trefoil (Lotus corniculatus)
Chile TrefoilShort-podded TrefoilAmerican TrefoilSmall-flowered TrefoilBird’s Foot Trefoil
Growth Habitground huggingground hugginggenerally uprightgenerally uprightgenerally upright
Leafletslightly hairy and fleshydensely hairy, silvered looking (also stems)hairynot hairy or sparsely hairednot hairy

fading to red

fading to red
pale pink to cream

banner veined
pale pink to cream

bright pink bud

fading to red
Habitatcommon in grasslandoccasional in coastal scrub and chaparraloccasional in grasslandoccasional in grassland and woodlandcommon in disturbed grasslands
Chile Trefoil (L), Short-podded Trefoil (M), American Trefoil (R) © DSchiel


Small-flowered Trefoil (L), Bird’s Foot Trefoil (R)
© KKorbholz

At Edgewood

  • Found in grasslands, scrublands, and disturbed areas
  • Flowers March – June

See General References

Specific References

Prigge, E. and A. Gibson. 2016. Acmispon wrangelianus. A Naturalist’s Flora of the Santa Monica Mountains and Simi Hills, California. Web version, hosted at Wildflowers of the Santa Monica Mountains National Recreation Area. United States Department of Interior, National Park Service.

Weiss, M. 1991, Nov. 21. Floral color changes as cues for pollinators. Nature 354: 227-229.