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
- Banner is blue with a white center, sometimes with small black spots
- 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.
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)
- Wildlife
- 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 food source (host) for several butterfly species, e.g. silvery blue (Glaucopsyche lygdamus), painted lady (Vanessa carduii), and acmon blue (Plebejus acmon)
- Native people
- Greens eaten after boiling to remove toxic alkaloids and protease inhibitors (Anderson 2005)
- CAUTION – Lupines contain varying amounts of toxic alkaloids
- Bitter taste deters herbivores
- Some species are poisonous to livestock and humans
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 7 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 6 other lupine species at Edgewood
- Sky lupine (L. nanus)
- 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 Lupine | Sky Lupine | Fleshy Lupine | Chick Lupine | Summer Lupine | Arroyo Lupine | Silver Bush Lupine | |
| Growth Habit | annual | annual | annual | annual | perennial herb | annual; can appear a perennial herb | woody shrub |
| Height | ≤ 16 in. | ≤ 24 in. | ≤ 20 in. | ≤ 31 in. | ≤ 31 in. | ≤ 39 in. | ≤ 16 ft., usually 3-5 ft. |
| Hairiness | hairy | hairy | hairy | sparsely to densely hairy | densely hairy | fleshy, sparsely hairy | silver-hairy |
| Leaflet Tip | sharply pointed | pointed | rounded or pointed | pointed | sharply pointed | wide, blunt | pointed |
| Inflorescence Length | ≤ 3 in. | ≤ 16 in. | ≤ 8 in. | ≤ 12 in., often in distinct tiers | ≤ 12 in. | ≤ 6 in. | ≤ 12 in. |
| Flower Color | blue ⋯ banner spot white > magenta | blue ⋯ 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 Arrangement | encircle stem | encircle stem | encircle stem | cluster to 1 side | encircle stem | encircle stem | encircle stem |
| Best Trails | Ridgeview, Sunset, Edgewood | Lower Clarkia | Lower Clarkia | Native Garden, Upper Sylvan | Upper Edgewood | Upper Sylvan | all trails |
At Edgewood
- Found in grasslands
- See iNaturalist for observations of this plant
- Flowers March – May
Specific References
Anderson, M.K. 2005. Tending the Wild. University of California, Berkeley. Pp. 274.
Ayers, G. 2016, Oct. 1. The controversy over nectar production. Introduction to genus Lupinus. American Bee Journal.
Elpel, T.J. 2013. Pea family – Fabaceae [Illustration of pea subfamily, adapted]. Botany in a Day: The Patterns Method of Plant Identification. HOPS Press, Pony, Montana.
Lady Bird Johnson Wildflower Center. 2018. Lupinus bicolor. Plant Database. University of Texas at Austin.
Stead, A.D. and M.S. Reid. 1990. The effect of pollination and ethylene on the colour change of the banner spot of Lupinus albifrons (Bentham) flowers. Annals of Botany 66: 655-663. Postharvest Center. Department of Plant Sciences, College of Agriculture and Environmental Sciences, University of California, Davis, and University of California Agriculture and Natural Resources (UC ANR).
Weiss, M. 1991, Nov. 21. Floral colour changes as cues for pollinators. Nature 354: 227-229.