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| Miniature (Bicolor) lupine (Lupinus bicolor) - in bloom |
Very
little is blooming in Mother Nature’s Gardens right now. But the recent rains have coaxed a number of
annual wildflower seeds to germinate. We’ve chosen one of these, the Bicolor or
Miniature lupine, as our Plant of the Month.
Like
many native species, Lupinus bicolor
is the subject of current taxonomic debate.
The species shows morphologic variability within its range, and variants
have been categorized as several separate species, as well as varieties and
subspecies of Lupinus bicolor. For simplicity, we’ll just discuss the
species as a whole. Former species which
now are included in Lupinus bicolor are:
Lupinus congdonii; Lupinus polycarpus;
Lupinus rostratus; Lupinus sabulosus; Lupinus umbellatus and possibly
others.
The
geographic range of Bicolor lupine stretches from British Columbia, Canada to
Baja California, Mexico. The species
grows throughout the California Floristic Province (West of the Sierras) and in
the western Mojave Desert. In Western
Los Angeles County, it can be found in the Santa Monica Mountains, on the
Southern Channel Islands and in the Los Angeles Basin from the Transverse
Ranges to the Pacific Ocean. It is a
common in open or disturbed areas from sea level to about 5000 ft. (1500 m.). Like many annual wildflowers, it can be found
in a number of California plant communities including the coastal strand, southern
coastal prairie, valley grasslands, joshua tree
woodland, yellow pine and mixed evergreen forest, and foothill woodland
communities.
Bicolor
lupine is one of about 75 species of Lupine native to California. About one-third of them – including Lupinus bicolor – are annuals; the rest
are perennials, sub-shrubs and shrubs. All
are members of the Pea Family, the Fabaceae.
Like many in this family, Lupines have a unique relationship with special soil
bacteria. These bacteria live within
nodules in the roots and convert nitrogen to a form that can be used by plants,
through a process known as nitrogen fixation.
When the root dies, the converted nitrogen is released into the soil,
improving soil fertility.
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| Miniature (Bicolor) lupine (Lupinus bicolor) - leaf |
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| Miniature (Bicolor) lupine (Lupinus bicolor) - plants |
Bicolor
lupine is a small annual, usually less than one foot tall locally, with medium-
to gray-green foliage clustered at the base of the plant. The palmately compound leaves, which look like an open hand, have 5 to 7
leaflets and are covered in short, transparent hairs. The leaf shape is typical for Lupines. As can be seen in the photograph above, the
hairs trap mist and fog quite effectively.
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| Miniature (Bicolor) lupine (Lupinus bicolor) flowers & seed pods |
The
flowers of Lupinus bicolor are petite
and charming, making them a favorite small wildflower. This is a fairly early bloomer – often
February or March in Western Los Angeles County, later in colder climates. The flowers, which are usually less than ½
inch across (1/4 to 1 inch; < 2.5 cm.) are arranged in a spiral pattern
(whorl) around short flowering stalks. The flowering stalks, often not much
taller than the foliage, usually have 4-10 flowers per stalk (see above).
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| Miniature (Bicolor) lupine (Lupinus bicolor) - flower details |
The
individual flowers have a shape typical for the Pea Family, with petals
modified into a ‘banner’, well-defined ‘wings’ and ‘keel’ (mostly hidden). The flowers are two-toned: the banner is white with blue-purple spots or blotches, while the wings are
blue-purple. Like other local lupines, the flower color changes from
blue-purple to red-purple after a flower is pollinated, sending a cue to insect
pollinators that no more nectar is being produced (see photo, above).
Miniature
lupine is insect pollinated, primarily by bees.
The insect lands on the wing petals, causing them to move and reveal the
sexual organs located in the keel. The
pollinating insect brushes against the stamens and
stigma while retrieving nectar, thereby pollinating the flower. The seeds develop in small ‘pea pods’ that
burst open explosively when dry (mid- to late-Spring), spreading the seeds.
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| Miniature (Bicolor) lupine (Lupinus bicolor) - young seedlings |
Bicolor
lupine is fairly easy to grow from seed.
Like all lupines, the seeds have a hard seed coat; germination is
enhanced by soaking them in hot tap water overnight before planting. Seeds can then be planted in prepared seed
beds or in pots for later transplanting.
Lupines tend to have long roots – in our area they are often easier to seed
directly into the garden rather than transplant. Be
sure to plant seeds on bare ground or under a thin gravel mulch. Plant just before a good rainstorm in late
fall or winter, then rake in lightly; seedlings will appear in several weeks.
Lupines
are an excellent source of nectar for bees, particularly the larger,
early-flying species. The foliage is a
larval food source for Orange Sulphur (Colias eurytheme) and several species of Blue butterflies. The seeds, which are toxic if eaten in
large quantities, are eaten by ground-foraging birds, particularly
Doves. They are an important food from
summer through fall.
In summary, Lupinus bicolor is an annual wildflower that does well
in California gardens and wildlands. It
likes sun, but is not particular about soil type. If winter rains are adequate, Bicolor lupine
needs no supplemental water, completing its life cycle before the summer dry
season.
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| Miniature (Bicolor) lupine (Lupinus bicolor) Madrona Marsh Preserve, Torrance CA |
We
like to use Lupinus bicolor along
pathways or in containers, where its small size can be adequately
appreciated. It is often grown, as in
nature, with other local annual wildflowers, California poppies and cool season
native grasses. It is a charming
seasonal groundcover on banks and around rain gardens and infiltration swales.
A
mass of Bicolor lupine, blooming in spring, is a sight for sore eyes. If happy, it will re-seed in local gardens,
returning whenever we have a rainy winter.
Lupinus bicolor is part of our
unique natural heritage and a welcome reminder of the climate cycles that so characterize
S. California.
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| Miniature (Bicolor) lupine (Lupinus bicolor) - mass planting |
For a
gardening information sheet see: http://www.slideshare.net/cvadheim/gardening-sheet-lupinus-bicolor
For more
pictures of this plant see: http://www.slideshare.net/cvadheim/lupinus-bicolor-web-show
For plant
information sheets on other native plants see: http://nativeplantscsudh.blogspot.com/p/gallery-of-native-plants_17.html
We
welcome your comments (below). You can
also send your questions to: mothernaturesbackyard10@gmail.com