Trifolium ambiguum M. Bieb.

Kura (Caucasian) Clover field - Hollander
Soil Improvement (Green manure)
Soil Protection (Cover Crop)

Long-lived, rhizomatous perennial legume also called Caucasian clover. Prostrate to erect stems, 1.5 feet (46 cm) in length, branching from the crown. Strong rhizomes form a dense mat of roots and daughter plants. Hairless oblong leaves with serrated margins, often with white V-shaped markings. Inflorescence is a head with mostly white to pink flowers. Used primarily for grazing, but first spring growth cycle can be harvested for hay or haylage. A valuable source of nectar for honey production. Tolerates close grazing due to extensive rhizomes and deep-seated crowns, which can be 2 inches (5 cm) below the soil surface. Kura tolerates stresses including cold, drought, low-fertility acid soils, and hard grazing. Poor seedling vigor, but persists once established. Production areas similar to white clover athough it is most productive in the northern US with available summer moisture.



Life cycle: 
Long-lived perennial
Growth Season: 
Identification Characteristics: 

Inflorescence is a large pink head. Flowers are white, turning pink-purple after anthesis. Stems are solid, oval in cross-section with few or no hairs. Leaves are palmately trifoliate. Leaflets are soft, smooth, with a variable pale green leaf marking, numerous branched veins and toothed margins. Stipules are broad at the base and gradually tapering to a point. Roots are highly branched with extensive rhizomes.

Kura requires cross-pollination by bees (honey, bumble, leafcutter, alkali) to produce seeds. Seed pods are brown and oval-shaped with one or two seeds. Seeds are yellow or red-brown, about 1.2 mm long and average about 670/g, roughly the same size as red clover (T. pretense) and larger than white clover (T. repens), varying from 450,000 to 880,000/kg depending on cultivar.

Growth Habit and Production

Growth Habit and Persistence: 

Low growing, spreading perennial.

Production Profile: 

First growth in spring contains an elongated stem that can be harvested for hay or silage. Subsequent growth is prostrate and leafy, with petioles supporting leaves originating from crowns and rhizomes. Greatest yields in spring, less in summer and fall.


Climate and Soil Suitability Zones

Climate Tolerances: 

Very winter-hardy, surviving extreme winter conditions in Minnesota and Wisconsin; suited to plant hardiness zones 3a-8. Greatest productivity with 25-40 inches (635-1000 mm) of precipitation or irrigation. Excellent drought tolerance, becomes dormant and regrows when soil moisture is replenished.

Soil Tolerances: 

Persists well on poorly drained to well-drained soils and tolerates strongly acid pH (5.1-7.3) and somewhat tolerant of aluminum (persists at 1-2 ppm Al3+). Tolerates long spring flooding periods (7-30 days, depending on temperature); is moderately sensitive to salinity (1.5-3 dS/m).

Quantitative Tolerances: 

Kura (Caucasian) Clover Suitability Tolerance Values

Suitability Class

Ave Annual Extreme Min (°C)*

July Max


Annual Precip (mm)**

Soil pH***

Soil Drainage 

Soil Salinity (dS/m)#








Moderately suited







Marginally suited







*Tolerates extreme winter conditions of MN and WI. USDA Plant Hardiness Zones 3a-8.

**Precipitation requirement: 25 inches (650 mm).

Rooting: extensively rhizomatous; depth to two feet (75 cm).

*** Soil pH tolerance: NRCS Range and Pasture Handbook, Chapter 3 classification is Strongly Acid: 5.1-7.3. . Y=101.8*EXP{-0.5*[(x -6.52)/0.885]2};R2=0.98; Optimum is 6.5. Minimum is 2.72 , Maximum is 10.32.

† Soil drainage: NRCS Range and Pasture Handbook, Chapter 3 classification for alsike clover is WD-PD. Soil drainage class abbreviations: 1=VPD, very poorly drained; 2=PD, poorly drained; 3=SPD, somewhat poorly drained; 4=MWD, moderately well drained, 5=WD, well drained; 6=SED, somewhat excessively drained; 7=ED, excessively drained. Class values relative yield for kura clover: 5, 20, 55, 100, 100, 55, 20. Y = 106.5*EXP{-0.5*[(x - 4.499)/1.336] 2}; R2 = 0.99.

#Soil salinity tolerance: NRCS Range and Pasture Handbook, Chapter 3 classification for clovers (alsike, Berseem, white, red, strawberry) is moderately sensitive (1.5-3 DS/m). Kura is not listed. MN Forage legumes table lists tolerance as Fair.  Y=100.23 - 7.61 x - 2.84 x2 (R2 = 0.99). Y=0, X=4.75.


Quality and Antiquality Factors

Quality Factors: 

Very leafy and high in feed value. Provides high quality summer forage with white clover, alfalfa, and fescue or phalaris grass species.

Anti-quality Factors: 

Low seedling vigor, often taking several years to establish. Similar bloat hazard as white clover and alfalfa.


‘Rhizo’ was released in 1990 by the NRCS and University of Kentucky. Improved cultivars with greater seedling vigor and forage potential include ‘Endura,’ ‘Cossack,’ and ‘NF-93.’ All cultivars are free of estrogenic compounds.


Image Gallery



Books and Book Chapters

  • Forages: An Introduction to Grassland Agriculture (7th Edition, 2018)
    • Sheaffer, Craig C., M. Scott Wells, and Jerry Nelson. 2018. Legumes for Northern Areas. Chapter 8 In: Forages: An Introduction to Grassland Agriculture. Seventh Edition. John Wiley & Sons, Inc.
  • Clover Science &Technology (Agronomy Monograph No. 25, 1985)

Journal Articles

Extension Fact Sheets and Circulars

  • Oregon State University 
  • University of Minnesota: Forage Legumes - Clovers, Birdsfoot Trefoil, Cicer Milkvetch, Crownvetch and Alfalfa. Station Bulletin 608-2003. (Out of print)
  • Purdue University: Kura Clover - New Crop FactSheet

USDA NRCS Plant Guide and Plant Profile