Trifolium fragiferum L.

Strawberry clover field - www.florevirtuelle.free_.fr_0.jpg
Symbol: 
TRFR2
Group: 
Dicot
Family: 
Fabaceae
Uses: 
Pasture
Hay
Silage
Soil Improvement (Green manure)
Soil Protection (Cover Crop)
Pollinators
Wildlife
Description: 

Herbaceous low-growing perennial with deep taproot and creeping stolons that root at nodes. Growth habit similar to white clover. Used for pasture and in mixtures with grass for hay and silage. Noted for its ability to establish and persist on wet, saline and alkaline soils. Often replaces white clover in sandy, coastal or river estuaries. A groundcover or green manure in orchards and vineyards. Forage and seeds of strawberry clover are also used by big and small game and upland birds.

Identification

Type: 
Legume
Life cycle: 
Long-lived perennial
Growth Season: 
Cool
Identification Characteristics: 

Inflorescence is sphere-shaped, borne on long peduncles (stalks). Flower head is 0.03-0.04 inch (10-12 mm) in diameter, slightly smaller than white clover with many small white or pink flowers whose base is covered with shining white hairs. Fertilized flowers inflate to enclose the ripening seed, turning paper-like in color and texture. When mature, the inflorescence looks more like a dried raspberry than the strawberry after which it is named. Stems are semi-erect, glabrous (not hairy), long (8-14 inches, 20-35 cm), and thin. Palmately trifoliolate leaves with equal-length petiolules. Leaflets are slender, spear-shaped, and closely veined; veining highly branched. Hairs on petioles and underside of leaflets. Stipules are glabrous, not toothed, with prominent veins. Deep taproot system. Seed pods are small, egg-shaped and contain 1 to 2 seeds. Seeds are heart-shaped (oval but slightly notched), light yellow to light brown with dark brown flecks. Seed count varies from 350,000-400,000 seeds/lb (770,000 to 880,000/kg).

Growth Habit and Stand Life

Growth Habit and Persistence: 

Prostrate growth habit similar to white clover. Deep taproot and stolons that root at the nodes. Greater persistence than white clover in hot, dry conditions.

Production Profile: 

Cool-season forage legume with the majority of production in late spring and early summer.

Climate and Soil Suitability Zones

Climate Tolerances: 

Strawberry clover survives a wide range of temperatures during the growing season, < 32 °F (0 °C) to > 95 °F, 35 °C); USDA Plant Hardiness zones 4a-9b. It is grown in the western and northern Great Plains states with mean minimum temperatures of -30 °F (-35 °C). Best production requires 25-40 inches (635-1000 mm) of precipitation or irrigation, but can survive in 18 inch (460 mm) rainfall zones.

Soil Tolerances: 

Grows in waterlogged, poorly drained, saline and alkaline soils; well-drained through poorly drained soil. Flooding tolerance is high (7-30 days); can survive up to 3 months of moving water immersion. Tolerates strongly acid to moderately alkaline soils (pH 5.1-8.4) and high salinity (6-10 dS/m).

Quantitative Tolerances: 

Strawberry Clover Suitability Tolerance Values

Suitability Class

Ave Ann Extreme Min (°C/°F)*

July Max

C/°F)

Annual Precip (mm/in)**

Soil pH***

Soil Drainage 

Soil Salinity (dS/m)#

Well-suited

-37/-35

30/86

1016/40

5.8-7.5

MWD-WD

<5

Moderately suited

-40/-40

31/88

815/32

5.5-8.0

SPD-SED

5-6

Marginally suited

-43/-45

32/90

610/24

5.0-8.5

PD-SED

7-8

* USDA Plant Hardiness Zones 4a-9b.

**Precipitation requirements: 25-40 inches (635-1000 mm) to thrive, can survive in 18 inch (460 mm) rainfall zones. Heat zones 32-34 °C; 88-92 °F

 Rooting: deep tap root and stolons – to > 3 feet (1 m)

*** Soil pH: NRCS Range and Pasture Handbook, Chapter 3 classification for Strawberry Clover is Strongly Acid to Moderately Alkaline (5.1-8.4).

Classifications – tolerant of soils that are: (1) Very strongly acid to strongly alkaline, 4.5–9.0; (2) Very strongly acid, 4.5–7.3; (3) Strongly acid, 5.1–7.3; (4) Moderately acid, 5.6–7.3; (5) Moderately acid to moderately alkaline, 5.6–8.4; (6) Slightly acid to moderately alkaline, 6.1–8.4; (7) Near neutral, 6.1–7.3; (8) Alkaline, 6.7–9.0.

Soil drainage: NRCS Range and Pasture Handbook, Chapter 3, Table 3-4; Classification for Strawberry Clover is Tolerant of PD to WD 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 Strawberry Clover for the classes 1-7: 25, 50, 75, 100, 100, 55, 30.

Flooding tolerance: (1) Very long (>30 days); (2) Long (7-30 days); (3) Brief (3-6 days)

# Soil salinity: NRCS Range and Pasture Handbook, Chapter 3, Table 3- classification for Strawberry Clover (and Alsike, Berseem, White, Red) clover is Moderately Sensitive (1.5-3 DS/m); however NRCS Species Guide indicates Strawberry Clover is the most saline tolerant legume and Australian Pasture Fact Sheet lists it as tolerant of Moderately Saline Soils (8-16 dS/m); thus herein classified as Moderately Tolerant.

Classifications are: (1) Tolerant, 6–10 dS/m; (2) Moderately Tolerant, 3–6 dS/m; (3) Moderately Sensitive, 1.5–3 dS/m.

Suitability Maps

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

 

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

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.

GIS-based quantitative tolerances maps

Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 

Quality and Antiquality Factors

Quality Factors: 

With adequate moisture, produces high quality summer forage.

Anti-quality Factors: 

Can cause bloat in ruminants and increase urinary calculi in sheep.  Manage these problems with a significant grass component in the pasture.

Cultivars

‘Salina’ released by the California Agricultural Experiment Station in 1962. ‘Fresa’ developed and released by New Mexico State University in 1982. The original collection was from Turkey and was selected for its low growing habit in southern New Mexico. ‘Palestine’, ‘Prinsep Park’, ‘O’ Connors’, ‘Grasslands Onward’ and ‘Grasslands Upward’ are strawberry clover releases developed and used in Australia and New Zealand. No serious disease or insect pests affect strawberry clover.

Species Selection Characteristics

Plant Hardiness Zones (cold tolerance): 
4a
4b
5a
5b
6a
6b
7a
7b
8a
8b
9a
9b
Soil pH Tolerance: 
Strongly acid, 5.1–7.3
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
Soil Drainage Tolerance: 
poorly drained
somewhat poorly drained
moderately well drained
well drained
somewhat excessively drained
excessively drained
Flooding Tolerance: 
7-30 days
Soil Salinity Tolerance: 
Moderately tolerant, 3–6 dS/m
Suitable Management Level: 
High
Medium
Low
Annual Precipitation (inches): 
24 to 28
28 to 32
32 to 36
36 to 40
40 to 50
50 to 60
60 to 70
70 to 80
80 to 100
100 to 120
120 to 140
140 to 160
> 160
Heat Zone (July Mean Max Temperature): 
< 14 °F
14 to 18 °F
18 to 22 °F
22 to 26 °F
26 to 30 °F
30 to 34 °F
34 to 38 °F
38 to 42 °F
42 to 46 °F
46 to 50 °F
50 to 53 °F
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
84 to 88 °F
88 to 92 °F

Image Gallery

Resources

Publications: 

Books and Book Chapters

  • Clover Science &Technology (Agronomy Monograph No. 25, 1985)

Extension Fact Sheets and Circulars

USDA NRCS Plant Guide and Plant Profile

Organizations

Vendors