Mima
Mounds Natural Area Preserve, Thurston Co., WA, 28.6.2000, Photo © Markku Savela
Prairie lupine (Lupinus lepidus var.lepidus)
Prairie lupine is a small
perennial lupine of diverse form and habitat in the
There are five known
varieties of Lupinus lepidus.
Variety lepidus is best described by it’s extended racemes
growing above the longest leaves and the length of it’s flowers between 11-13mm
long.1
Range
Prairie lupine (var. lepidus)
is distributed in the lowlands west of the
Climate, elevation
Prairie lupine may be found
in lowland areas growing in arid climates (40-65 inches of annual
precipitation) at elevations below 600 feet.[4]
Local occurrence
Habitat preferences
Prairie lupine occurs in lowlands
on gravelly to sandy soils, often on flat or mounded plains of recessional
glacial outwash.4
Plant strategy
Lupinus lepidus var.
lobbii was
the first plant to colonize the devastated slopes of Mount St. Helens[5] Seeds are probably dispersed by explosive
dehiscence (bursting of the seed pods) and rolling, or by erosion and
deposition.[6]
Associated species
Species associated with
Prairie lupine include houndstongue hawkweed (Hieracium cynoglossoides), cutleaf microseris (Microseris laciniata), spike
goldenrod (Solidago spathulata),
white-top aster (Aster curtus), and slender
cinquefoil (Potentilla gracilis).
Long-stolon sedge (Carex pensylvania), field woodruch (Luzula campestris),
Collect as seed
Hairy pods range from 10-20 cm long with 2-12
seeds.2
Collection guidelines
Seed can be hand collected from
June to August, but collecting is slow due to the small size of the plant. Seeds
should be dried in the pods in paper bags. Remove the seeds from the pods by hand
thresh and screen.7
Cuttings can also be taken
from the side shoots of hardened stems in the spring[7]
Seed germination
Seed requires scarification.
Shake in jar half-filled with coarse sand, scarify with sand paper7,
or rock tumbler for two hours.
After scarification, soak in
hot water until the water has cooled (approximately 3 hours). Seeds that sink
have absorbed enough water to be sown. Those that do not sink should be dried,
scarified and soaked in water again.
Seed life
Lupine seeds have a hard
seed coat, and because related lupine species are known to have long-lived
dormant seed banks (e.g. L. arboreus was germinated in a seed bank study after
45 years), it is likely that prairie lupine seeds are also long-lived
and can be stored at low moisture and temperature levels for several years.
Seed storage
Store air-dried seed under
cool, dry conditions. Protect from small mammals and rodents.
Propagation
Plant seeds singularly in
long narrow pots (at least 3”) and transplant from pots into the field within
the same year (about 8 months).
Lupine seedlings have very
sensitive roots and suffer from root damage when handled excessively.
Sensitivity to the root system is especially needed when transplanting from
nursery containers into the field.
Soil requirements
Sow lupine seeds in potting
soil mixture of coarse and fine particles. Like other legumes prairie lupine
has root nodules which house bacteria which fix nitrogen, providing fertilizer
for the plant. Potting soil can be inoculated by mixing a small amount of soil
from the seed collection site in the potting mix. Use low nitrogen fertilizer
and no humus.
Planting density
1-2 foot centers
Care requirements
Seedlings develop very long
roots and should be transplanted with sensitivity restricting damage during
transplanting.
Mist lightly, daily with
restricted water.
Rate of growth
Rate of growth is variable.
First year growth is limited due to resources needed to develop large root
systems, particularly in rocky soils.
Data compiled by Amy Lambert,