Idaho Plant Materials Technical Note No. 24

Sweetclover, Yellow Melilotus officinalis Sweetclover, White M. alba
Sweetclover is an introduced, tall, stemmy, deep rooted, biennial legume. It produces an abundance of forage the first
two years and is commonly utilized as a cover crop for perennial seedings. It reseeds and maintains good stands where
perennials do not crowd it out and in years of above normal precipitation. It is poor quality forage at mid to later
growth stages. It is adapted to many sites including sagebrush-grass to subalpine areas, moist salty lowlands, road cuts
and roadsides but does not tolerate acid soils. It maintains stands in grass where ample moisture is available. It is
suited for green manure or green-chop haylage under irrigation or on dryland where the effective annual precipitation is
15 inches or more. Sweetclover is the most drought tolerant commercially available legume and has been used
successfully in plantings that receive as little as 9 inches effective precipitation. It is a good pollinator species and
blooms in spring into early summer. Sweetclover contains Coumadin, a derivative of dicoumarol, a blood anticoagulant.
Death may occur in animals foraging on pure stands or from spoiled hay or silage. Sweetclover is
sometimes considered to be a weedy or invasive species, particularly in years with very wet late winters and springs.
The planting depth is 1/8 to 1/2 inch. Adapted varieties are ‘Norgold’, 'Madrid', ‘Polara’ and “Yukon’. Average
seeds/ft 2 at 1 lb. rate is 6. Pure stand seeding rate is 4 lb/ac. Do not exceed 1 lb/ac of seed in conservation, rangeland
and pollinator seed mixtures.
Sweetvetch, Northern or Utah
Hedysarum boreale
Northern or Utah sweetvetch is a native perennial legume. This species occurs in foothills and upland areas that
receive 10 or more inches of annual precipitation. Sweetvetch prefers well-drained soils ranging from rocky, gravelly,
and sandy to heavy clay. Its deep taproot enables it to take advantage of deep soil moisture that results in considerable
drought resistance and winter hardiness. Seed should be fall seeded at 1/8 inch to 3/4 inch deep. It is very slow to
establish in mixed stands and requires alternate row planting to provide optimum establishment. Livestock and big
game graze this species when available. It is considered a good pollinator species with red to purple flowers that bloom
in May-June. Spring green up occurs early, and basal leaves remain green throughout the winter. 'Timp' is a release
from Meeker PMC. Average seeds/ft 2 at 1 lb. rate is 1. Pure stand seeding rate is 24 lb/ac. Not recommended for pure
stands.
Tansyaster, Hoary
Machaeranthera canescens
Hoary tansyaster is a short-lived perennial native forb with a moderate growth rate and erect stature 6-30 inches tall. It
is common in plant communities including shadscale and Wyoming big sagebrush on valley floors to mountain big
sagebrush, aspen and limber pine on mountain slopes. It is common in low seral degraded to disturbed sites and is
sometimes considered to be a weedy species on rangelands. It is considered an excellent wildlife forage and a good
insect producing species. It is an excellent pollinator species with blue to purple flowers that bloom from late July into
October. It attracts bees, butterflies and moths. Average seeds/ft 2 at 1 lb. rate is 30. Pure stand seeding rate is 1 lb/ac.
It is recommended as component in rangeland, pollinator and sage grouse seed mixtures. It is normally less than 10%
of the seed mixture.
Trefoil, Birdsfoot
Lotus corniculatus
A short-lived, deep-rooted, non-bloat introduced legume suited for use as pasture or hay. It can be grown under
irrigation or on dryland where the effective annual precipitation is 18 inches or more. It is very winter hardy (where
protected by snow cover), resistant to water logged soils, and useful at high elevations. It is better than alfalfa for
retaining high quality forage on mature growth. The decumbent types are more tolerant to close grazing than erect
types. Tolerant of poor drainage, this legume is quite vigorous and an excellent plant for erosion control, big game
forage, pollinator plantings and beautification. The yellow flowers attract bees from June-August. If plants are allowed
to go to seed, stands will persist for many years. It is short lived (2-4 years), making reseeding necessary. It is a
nuisance in subsequent crops because of its ability to recruit from the seedbank. It may invade adjacent areas that have
similar growing conditions. Planting depth is 1/4 to 1/2 inch. Recommend alternate row plantings to allow birdsfoot
trefoil to establish when planted as part of a seeding mixture that includes grasses. Adapted varieties are 'Empire'
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