We are following the treatment in the USDA on-line resource 'Plants Database', but this species is sometimes treated as a subspecies of Lupinus microcarpus Sims. (as Lupinus microcarpus densiflorus (Benth.) Jeps.)

Common Name:

General Information

Lupinus densiflorus is an annual plant with stems that are simple or branched above; it can grow up to 40cm tall[].
The plant is sometimes harvested from the wild for local use as a food. It is used as a green manure and is often grown as an ornamental in gardens.

Known Hazards

Lupinus species in general (and especially the seeds) contain a range of bitter-tasting alkaloids such as lupine, anagyrine, sparteine and hydroxylupanine. The pharmacological effects of these alkaloids are that they block ganglionic transmission, decrease cardiac contractility and contract uterine smooth muscle[]. When ingested in moderate to large quantities they can cause symptoms such as respiratory depression and slow heartbeat, sleepiness and convulsions[].
Alkaloid levels can vary greatly from species to species, and several members of the genus are used for food. In some species low-alkaloid, sweeter-tasting varieties have been developed. There are also techniques (particularly soaking and discarding the soak water) that lower the alkaloid levels.
Unless it is known that the plant is low in alkaloids then caution should be applied to any ingestion of the plant[].
Fungal toxins can readily invade the crushed seed and can cause chronic illness[].

Botanical References

Range

Western N. America - British Colombia, Washington, Oregon, California

Habitat

Grassy and open fields and hillsides in mixed evergreen forest, coastal ranges etc; at elevations up to 600 metres[].

Properties

Edibility Rating
Other Uses Rating
Habit	Annual
Height	0.30 m
Pollinators	Bees, Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Members of this genus are mainly found in dry habitats, often on stony and low fertility soils[]. In cultivation they generally grow well if given a sunny position in a deep, well-drained, moderately fertile soil with a neutral to slightly acid pH[].
The plant is sometimes grown as an ornamental, there are some named varieties[].
A very variable species, six varieties are recognized, five of them restricted to California.This species has a symbiotic relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

Leaves and flowers - cooked[]. Steamed and eaten with acorn soup[].

Medicinal

None known

Agroforestry Uses:

The plant is grown as a green manure and is useful for soil renovation and stabilization[].

Other Uses

We have no specific information for this species, but the soakwater used to extract alkaloids from several edible species of lupin has been shown to be effective as a biocide[].

Propagation

Pre-soak the seed for 24 hours in warm water and sow in mid spring in situ[, ]. You may need to protect the seed from mice. Germination should take place within 2 weeks.
The seed can also be sown in situ as late as early summer as a green manure crop.