Miniature Lupine

Miniature Lupine © DSchiel

Bicolor Lupine
Lupinus bicolor
NATIVE

Description (Jepson, PlantID.net)

  • Eudicotyledon
    • Eudicots are a major lineage of flowering plants; see family for general characteristics
  • Pea Family (Fabaceae)
  • Annual herb (may live 2 seasons in some areas)
  • Stems are short and hairy (pubescent)
  • Leaves
    • Palmately compound (separate leaflets radiating from a single point)
    • 5-7 narrow leaflets
    • Hairy
  • Flowers
    • Inflorescence (flower arrangement) is a raceme (unbranched stem with stalked flowers opening from the bottom up)
    • Arranged in whorls (3 or more leaves/flowers at each junction with stem)
    • Characteristic Pea family flower is bilaterally-symmetric, with a banner, wings, and keel
      • Banner is blue with a white center, sometimes with small black spots
        • With aging or pollination, white center turns magenta
      • Wings are blue
      • Keel is white
    • Ovary superior (above the attachment of other flower parts)
  • Fruit is a thin, short, hairy legume (a single-chambered seed pod that opens along 2 seams), up to 1 in. long
  • Height to 16 in.
Pea Flower
Flower © DSchiel

Distribution

  • Native to California
    • Grows in a variety of habitats including coastal scrub, conifer forests, mixed evergreen forests, foothill woodlands, and grasslands
    • See Calflora for statewide observations of this plant
  • Outside California, grows from British Columbia to Baja California, Mexico
  • Grows at elevations to 5,250 ft.

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

  • Frequented by bumblebees and other native bees
  • Authorities differ on the production of nectar in lupines, perhaps because nectar production may differ by species; see Ayers (2016) for a summary of the controversy
  • Larval host to several butterfly species including silvery blue (Glaucopsyche lygdamus), painted lady (Vanessa carduii), and acmon blue (Plebejus acmon)
  • CAUTION – Lupines contain varying amounts of toxic alkaloids
    • Bitter taste deters herbivores
    • Some species are poisonous to livestock and humans
Field of Miniature Lupine © SBernhard

Name Derivation

  • Lupinus (loo-PIE-nus) – from the Latin for “wolf”; it was mistakenly believed that lupines depleted soil of nutrients
  • bicolor (BYE-kol-or) – from the prefix bi-, “two,” and “color,” referring to 2 colors of the flower
  • Miniature lupine – refers to its diminutive size relative to most lupine species

Notes

  • Miniature lupines often grow in large patches that sweep across open, sunny areas, making a bright, contrasting background for orange poppies (Eschscholzia californica), pink owl’s clovers (Castilleja species), and other spring wildflowers
  • Like almost all members of its family, miniature lupine fixes nitrogen; see Pea family for more details
  • Banner spot of lupine flowers changes color as the flower ages (Stead and Reid 1990)
    • This change occurs more quickly after pollination
    • Even though the flower shows no sign of wilting, color change tells visiting insects to move on to another flower
    • These unwilted, pollinated flowers remain to help attract pollinators from a distance
    • Flowers from more than 70 plant families use color changes to direct pollinators (Weiss 1991)
  • Jepson notes that Lupinus bicolor is highly variable, with many subspecies and varieties indistinct in form and distribution
  • Edgewood has 6 lupine species, a remarkable number for a relatively small preserve and an indication of Edgewood’s species diversity

ID Tips

  • Flowers and leaves of lupines are characteristically similar
  • Miniature lupine is the only lupine at Edgewood that makes carpets of color in the grasslands and is generally smaller than the others
  • May be confused with the 5 other lupine species at Edgewood
    • Fleshy lupine (L. affinis)
    • Chick lupine (L. microcarpus var. densiflorus)
    • Summer lupine (L. formosus var. formosus)
    • Arroyo lupine (L. succulentus)
    • Silver bush lupine (L. albifrons var. albifrons)
Miniature LupineFleshy LupineChick LupineSummer LupineArroyo LupineSilver Bush Lupine
Growth Habitannualannualannualperennial herbannual; can appear a perennial herbwoody shrub
Height≤ 16 in.≤ 20 in.≤ 31 in.≤ 31 in.≤ 39 in.≤ 16 ft., usually 3-5 ft.
Hairinesshairyhairysparsely to densely hairydensely hairyfleshy, sparsely hairysilver-hairy
Leaflet Tipsharply pointedrounded or pointed pointedsharply pointedwide, bluntpointed
Inflorescence Length≤ 3 in.≤ 8 in.≤ 12 in., often in distinct tiers≤ 12 in.≤ 6 in.≤ 12 in.
Flower Colorblue

banner spot white > magenta
blue-purple

banner spot white > magenta
white to yellow; rose to purple

no banner spot
faded blue-purple

banner spot white or none
blue-purple

banner spot white > magenta
blue-purple

banner spot white to yellow > magenta
Fruit Arrangementencircle stemencircle stemcluster to 1 sideencircle stemencircle stemencircle stem
Best TrailsRidgeview, Sunset, EdgewoodLower ClarkiaNative Garden, Upper SylvanUpper EdgewoodUpper Sylvanall trails

At Edgewood

  • Found in grasslands
  • Flowers March – May

See General References

Specific References

Ayers, G. 2016, Oct. 1. The controversy over nectar production. Introduction to genus Lupinus. American Bee Journal.

Lady Bird Johnson Wildflower Center. 2018. Lupinus bicolor. Native Plants of North America. University of Texas at Austin.

Stead, A.D. and Reid, M.S. 1990. The effect of pollination and ethylene on the colour change of the banner spot of Lupinus albifrons (Bentham) flowers. Annals of Botany 66, pp. 655-663.

Weiss, M. 1991, Nov. 21. Floral color changes as cues for pollinators. Nature, vol. 354, pp. 227-29.