Trifolium resupinatum L.

Persian Clover field flowering - Hollena Nori

Persian clover (Trifolium resupinatum L.) is an annual, herbaceous legume with prostrate or semi-erect growth habit to 4 feet (1.2 m). It forms dense swards and has a rosette growth habit under grazing.

It is mostly used for pasture and hay, producing highly palatable and nutritious forage. Its high protein and moisture content make it difficult to ensile. Soft-seeded cultivars are used for hay and silage, while hard-seeded varieties are used on dryland pastures. Soft-seeded cultivars are not well suited for dryland pastures, as the seeds germinate quickly during summer and young plants often die during dry periods. 

It has high forage yield and excellent regrowth following grazing or cutting.

Soil Improvement (Green manure)
Soil Protection (Cover Crop)

Species Selection Characteristics

Annual Precipitation (inches): 
16 to 20
20 to 24
24 to 28
28 to 32
32 to 36
36 to 40
Plant Hardiness Zones (cold tolerance): 
Heat Zone (July Mean Max Temperature): 
53 to 56 °F
56 to 59 °F
59 to 62 °F
62 to 65 °F
65 to 68 °F
68 to 71 °F
71 to 74 °F
74 to 77 °F
77 to 80 °F
80 to 84 °F
Soil pH Tolerance: 
Moderately acid, 5.6–7.3
Moderately acid to moderately alkaline, 5.6–8.4
Slightly acid to moderately alkaline, 6.1–8.4
Near neutral, 6.1–7.3
Alkaline, 6.7–9.0
Soil Drainage Tolerance: 
poorly drained
somewhat poorly drained
moderately well drained
well drained
Flooding Tolerance: 
7-30 days
Soil Salinity Tolerance: 
Moderately tolerant, 3–6 dS/m

Identification Characteristics

Growth Season: 
Identification Characteristics: 

Inflorescence is a flattened head with highly fragrant, pink to purple flower petals having a resupinate (inverted or upside down) corolla, hence the name resupinatum.

Single-seeded pods split open at maturity. Seeds are tan to reddish-brown and very small (364,000-900,000/lb; 800,000–2,000,000/kg).

Stems are hollow, branching from the base.

Leaves are trifoliolate with 0.4 to 1.2 inch (1-3 cm) long oval to oblong serrated leaflets. Stipules pointed with red veination.

Roots: tap rooted.        

Growth Habit and Stand Life

Prostrate or semi-erect growth habit to 2 feet (60 cm). Forms dense swards and has a rosette growth habit under grazing.

Life Cycle: 
Winter annual

Climate and Soil Suitability Zones

Climate Tolerances: 

Originating in central Asia and the Mediterranean area, Persian clover is traditionally cultivated in cold areas in the Middle-East and central Asia (Iran, Afghanistan, and northern Pakistan). In the USA, Australia, and France, it is a minor fodder crop which is well suited to areas with a summer dry, Mediterranean type climate. 

Suited to USDA Plant Hardiness Zones 7b-9b. It can survive cold winter temperatures (to 10°F, -12 °C) and frost, but develops slowly at low temperatures. Moderate heat tolerance, suited to July mean maximum temperatures of 79-82 °F (26-28 °C). Requires at least 18 inches (450 mm) of annual precipitation.

Soil Tolerances: 

Suited to sandy to loam to clay-loam soils with a pH between 5.5 and 9, with optimum growth in neutral to slightly alkaline soils (pH 7-8). It tolerates waterlogging, mild salinity (3-5 dS/m).

Quantitative Tolerances: 

Persian Clover Suitability Tolerance Values

Suitability Class

Jan Min (°C)*

July Max


Annual Precip (mm)**

Soil pH***

Soil Drainage 

Soil Salinity (dS/m)#








Moderately suited







Marginally suited







*Low temperature: USDA Plant Hardiness Zones: 7b-9b

   Rooting: taproot to 3 feet (90 cm).

*** Soil pH: Strongly Acid to Moderately Alkaline: 5.5-9.0. 

† Soil drainage: Tolerates water-logged soils. 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. Percent relative yield for balansa clover for the classes 1-7: 15, 40, 75, 100, 100, 55, 20, respectively.

# Soil salinity: Mildly saline soils (3-5 dS/m)

Suitability Maps

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database. The procedure used to produce these suitability maps is described below.

Suitability curves were developed for each clover species for three climate variables (average annual precipitation, average July maximum temperature, and average annual extreme low temperature) and three soil variables (drainage class, pH, and salinity). For each variable and each species, the curves were fit using estimated yield data across the full range of values for the given variable.  

The coefficients for the model equations were applied to spatial data layers representing each climate and soil variable, resulting in spatial outputs of percent yield for each of the clover species and each climate and soil variable. The percent yield layers were then classified into four suitability classes, as follows: 

100%-75% - Suitable
75%-50%  - Moderately suitable
50%-25%  - Marginally suitable
25-0%    - Not suitable

Finally, three "hybrid" suitability layers were produced for each clover species based on combinations of 1) the three climate variables, 2) the three soil variables, and 3) all six climate and soil variables together.  These combined suitability layers were created by selecting for each location the lowest suitability value of the included variables, with the idea that the overall suitability for a species will be limited by the most restrictive factor. 


The contiguous USA

Climate Factors

Soil Factors

Combined Factors

Minimum Temperature


All climate and soil factors (most limiting)



Maximum Temperature


All soil factors (most limiting)




All climate factors (Most limiting)

Yield Potential and Production Profile

In moderately cold areas, it can be sown in autumn to be used during spring. In extremely cold areas it is often sown in the late spring in combination with wheat, so that it is available for grazing or hay once the cereal crop has been harvested. In warmer regions, Persian clover is fall-sown, harvested in early spring and followed by a cereal grain crop.

Persian clover can be cut 2 or 3 times, but not closer than 4 inches (10 cm) to allow for vigorous regrowth. In irrigated fields the optimum cutting interval is approximately 6-9 weeks in the growing season, allowing dry matter yields of 5-6.5 tons/ac (12-15 t/ha). Planting rate is 6 to 8 lb/acre (5-10 kg/ha).


There are two main subspecies of Trifolium resupinatum: majus and resupinatum. Trifolium resupinatum var. majus has an erect habit, thick hollow stems and large leaflets. Hard seed level is very low (1-2%). Flowering and maturity is mostly late. The cultivars Maral, Morbulk, Laser, and Lightning belong to this subspecies. They are typically planted alone or in combination with oats or annual ryegrass in regions with >600 mm per year or in irrigated systems.

Trifolium resupinatum var. resupinatum has a more prostrate habit, thinner stems, and smaller leaflets. Hard seed and seed yields are higher than majus. Flowering and maturity are mostly earlier than majus. The cultivars Kyambro, Nitro, and Prolific belong to this subspecies. Subspecies resupinatum is sown in dryland systems in regions with >450 mm per year as a winter forage crop in warmer areas or as a summer annual in more northern or higher elevation areas.

Management Level Required

Suitable Management Level: 

Quality and Antiquality Factors

Quality Factors: 

Forage is palatable with high digestibility and crude protein (16-28%).

Anti-quality Factors: 

It can produce bloat in cattle and photosensitization may occur on pure stands grazed by sheep.

Image Gallery



Department of Primmary Industries, New South Wales. 2018. Persian Clover.

Heuzé V., Tran G., Giger-Reverdin S., Lebas F. 2015. Persian clover (Trifolium resupinatum). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO.      Last updated on September 30, 2015.

McCaskill M., Borg, D. 2006. Managing pastures in saline areas.

Moot, Derick and Dick Lucas. 2012. Legumes for Hill Country.

New England Wild Flower Society - Go Botany.

Onal O., Kask Y., Nalbanto F., Deveci M., Acar Z. 2016. The nutritive value of Persian clover (Trifolium resupinatum) herbage grown under irrigation in northern Victoria.  Options Mediterranéenes 14: 201-204.