Burclover (Polymorpha)

The Burclover (Polymorpha) is generally described as a perennial forb/herb. This is not native to the U.S. (United States) and has its most active growth period in the fall and winter and spring . The greatest bloom is usually observed in the winter, with fruit and seed production starting in the spring and continuing until summer. Leaves are not retained year to year. The Burclover (Polymorpha) has a short life span relative to most other plant species and a moderate growth rate. At maturity, the typical Burclover (Polymorpha) will reach up to 1.3 foot high, with a maximum height at 20 years of 0 inches.

The Burclover (Polymorpha) is easily found in nurseries, garden stores and other plant dealers and distributors. It can be propagated by seed. It has a moderate ability to spread through seed production and the seedlings have medium vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below 32°F. has none tolerance to drought and restricted water conditions.

Uses of : Landscaping, Medicinal, Culinary, etc.

Livestock: All classes of livestock except horses and mules will eat burclover readily, especially when the plant is maturing. Mature stands are highly nutritious and, when abundant, may serve as a finishing feed for lambs. Where growth is lush, the herbage has been known to cause bloat in livestock, particularly those unaccustomed to grazing it. Heavy use of the pods is most noticeable after the spiny burs have been softened by fall rains. While summer grazing burclover, sheep often accumulate numerous burs in the wool, lessening the value of the clip.

Cropland: Burclover is commonly used as a cover crop in orchards. Its rapid, dense growth characteristics and its ability as a legume to fix nitrogen and thus increase the available soil nitrogen supply add to its value for such use. Burclover is particularly useful in orchards and vineyards as a reseeding annual used in association with strip cover management. It can be mowed to control excessive growth, which will not hinder its ability to produce a seed crop for the next year. After seed maturity it can be mowed or disked.

Wildlife: Quail and deer make extensive use of the dry burs.

General Characteristics

Medicago polymorpha L., burclover, is a shallow-rooted annual legume. The characteristic growth habit of burclover is one of numerous prostrate stems branching from the crown and spreading outward 6 to 30 inches. Where thick stands develop stems may become erect, obtaining heights of 18 to 24 inches in more favorable years. The leaves are subglabrous and clover-like in appearance, with leaflets normally wedge-shaped and toothed toward the top. The inflorescence is usually quite limited, presenting only a few small, yellow, pea-like flowers. The several-seeded fruit is a flattened, coiled pod, commonly up to 1/4 inch in width and fringed with a double row of conspicuous, hooked spines. Well developed plants may produce more than 1,000 pods. The seed is rather large for a legume of this type, usually developing to over 3/32 inch in length.

Although often considered an indigenous California plant, burclover was introduced from southern Europe. Burclover has become extensively naturalized in the United States from cultivation as a hay or cover crop. It is one of the more widely recognized Medicago species, especially west of the Sierra Nevada and Cascade Mountains, where it is most abundant.

Required Growing Conditions

Burclover may occur in pure stands, but most often it is associated with other winter annuals, such as soft chess, wild oats, and filaree species. As a winter annual, burclover germinates in autumn following the first rains of the season and matures early in the summer. It is particularly adapted to mild, moist winters and hot, dry summers. Optimal annual rainfall for burclover is 10 to 25 inches.Although burclover will succeed in many soil types, heavy loams are most suitable and valleys and low foothills are generally the preferred sites of natural plant development. This species inhabits all exposures and grows well under light conditions varying from full sunlight to heavy shade. It is tolerant of slightly alkaline conditions and is less acid tolerant than subterranean clover. Favorable growth is usually restricted to a soil pH range of 4.7 to 8.0. Flowering period for burclover commonly begins in February. On very moist soils, the plants are later maturing than on well-drained lands.

Cultivation and Care

Burclover does poorly on soils of low fertility. In establishing stands, except on very fertile soils, the use of fertilizer is routinely recommended. Growth is especially poor on droughty, sulfur deficient, granite soils and fertilization with sulfur and phosphorous is required.Seedings of burclover are made in late summer or early fall. Later seeding provides little time for fall and winter growth and plants are more susceptible to cold temperatures and frost-heaving. The recommended seeding rate is 9 pounds per acre. In dry areas, one irrigation period just before seeding is ordinarily required. Earlier seeding or unusually dry falls may necessitate a second irrigation to keep seedlings from being lost to drought.Naturalized stands of burclover usually have adequate seed inoculation. For added success in developing new stands, inoculation of the seed with commercial inoculate is recommended. Scarification of the seed may also be necessary to ensure proper establishment.

General Upkeep and Control

Where burclover is adapted on rangeland, seeding is usually not necessary as the seed is already present. Production can be enhanced with cultivation, fertilization and proper grazing management. Existing stands in orchards and vineyards will continue to re-seed indefinitely under proper management. Wait for seed to mature before spring tillage. Don't apply herbicide to strips intended for cover crop. Use phosphorous and sulfur to encourage burclover in mixed grass-clover stands.

Cultivars, Improved, and Selected Materials (and area of origin) No cultivars are specifically recommended. Other species of burclover include Medicago rigidula (L.) All. and Medicago hispida Gaertn. Seeds are available at commercial seed stores in the west.

Plant Basics
Growth Rate Moderate
General Type Forb/herb
Growth Period Fall, Winter, Spring
Growth Duration Annual, Perennial
Lifespan Short
Plant Nativity Introduced to U.S.
Commercial Availability Routinely Available
Physical Characteristics
Bloom Period Winter
Displays Fall Colors No
Shape/Growth Form Single Crown
Drought Tolerance None
Shade Tolerance Intolerant
Height When Mature 1.3
Vegetative Spread None
Flower Color Yellow
Flower Conspicuousness No
Fruit/Seed Abundance High
Fruit/Seed Seasonality Spring Summer
Seed Spread Rate Moderate
Gardening Characteristics
Propagations (Ways to Grow) Seed
Moisture Requirements Medium
Cold Stratification Required Yes
Minimum Temperature 32
Soil Depth for Roots 12
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Regrowth Rate Slow
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 5.9–8.2 pH
Precipitation Range 12–12 inches/yr
Planting Density 0–0 indiv./acre
Soil Textures Fine, Medium
Soil Depth for Roots 12
Minimum Frost-Free Days 100 day(s)
Salinity Tolerance None
CaCO3 Tolerance None
Sustainability & Use
Leaf Retention No
Palatability Medium
Fire Resistant No
Causes Livestock Bloating Low

Source: USDA, NRCS, PLANTS Database, plants.usda.gov.
National Plant Data Center, Baton Rouge, LA 70874-4490 USA