Common Name: Subterranean Clover

General Information

Trifolium subterraneum is a prostrate annual plant with a relatively strong tap root. It usually grows 15 - 30cm tall, branching from the base, with prostrate stems 3 - 20cm long, occasionally to 60cm[, ].
The plant is harvested from the wild for local use as a food. It is often grown as a green manure and for soil stabilization.
Trifolium subterraneum has a large geographical distribution and is known to occur within the protected areas network. The taxon is not considered to be specifically threatened or in decline at present. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

Eating this plant can cause bloat, especially if larger quantities are consumed[].

Botanical References

Range

Europe - Britain to Portugal, east to Ukraine, Greece and Bulgaria; W. Asia - Turkey, Caucasia, Levant; N. Africa - Morocco to Tunisia

Habitat

Sandy and gravelly pastures, also on cliff tops, avoiding acid soils and shady positions[]. Humid soils of open plains and in mountains; at elevations from sea level to 1,800 metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Other Uses Rating
Habit	Annual
Height	0.20 m
Pollinators	Insects
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Trifolium subterraneum is a plant of the temperate to subtropical zone, especially in the Mediterranean, where it is found at elevations up to 1,300 metres. It grows best in areas where annual daytime temperatures are within the range 5 - 25°c, but can tolerate 3 - 30°c[]. When dormant, the plant can survive temperatures down to about -15°c, but young growth can be severely damaged at 0°c, though there are also reports that well-established seedlings can survive -15°c[]. It prefers a mean annual rainfall in the range 500 - 1,000mm, but tolerates 250 - 1,630mm[].
Succeeds in a moist, well-drained circum-neutral soil, preferring a position in full sun, but tolerating light shade[, ]. Succeeds in poor soils[]. Prefers a pH in the range 5.5 - 6.5, tolerating 4.5 - 8.2[].
Plants are partially winter hardy[].
Subterranean clover is indigenous to the Mediterranean region. It is best suited to regions with mild winters and warm, dry summers[].
Yields of green manure may be about 35 - 40 tonnes per hectare[].
Autumn sown in Brazil, the plant can provide groundcover in 90 - 115 days, flowers after 95 - 130 days, and mature in 140 - 190 days[].
It makes permanent pastures lasting up to 25 years. It propagates itself by seed[].
After flowering, the fruiting head grows into the ground, thereby planting the seed.
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[]. Buttercups growing nearby depress the growth of the nitrogen bacteria by means of a root exudate[]. When removing plant remains at the end of the growing season, it is best to only remove the aerial parts of the plant, leaving the roots in the ground to decay and release their nitrogen.

Edible Uses

Leaves - raw or cooked.

Medicinal

None known

Agroforestry Uses:

This plant can be grown as a ground cover green manure under tomatoes in the greenhouse. The seed should be sown before planting the tomatoes[]. It can also be sown under soft fruit and cut once or twice in the summer[].
It also provides good erosion control[].
This species grows well in an apple orchard, the trees will produce tastier fruit that stores better[]. It should not be grown with camellias or gooseberries, however, because it harbours a mite that can cause fruit drop in the gooseberries and premature budding in the camellias[].

Other Uses

None known

Propagation

Pre-soak the seed for 12 hours in warm water and then sow in spring in situ.
If the seed is in short supply it might be better to sow it in pots in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in late spring.