Gliricidia sepium

Description

Gliricidia sepium is a medium-sized tree that grows 10 to 12 meters high. The bark is smooth, and its color can range from a whitish gray to deep red-brown.

It has composite leaves that can be 30 cm long. Each leaf is composed of leaflets that are about 2 to 7 cm long and 1 to 3 cm wide.

The flowers are located on the end of branches that have no leaves. These flowers have a bright pink to lilac color that is tinged with white. A pale yellow spot is usually at the flower's base.

The tree's fruit is a pod about 10 to 15 cm long. It is green when unripe and becomes yellow-brown when it reaches maturity. The pod produces 4 to 10 round brown seeds.

G. sepium is native to tropical dry forests in Mexico and Central America. In addition to its native range it is cultivated in many tropical and subtropical regions, including the Caribbean, northern parts of South America, central Africa, parts of India, and Southeast Asia.

The tree grows well in acidic soils with a pH of 4.5-6.2. The tree is found on volcanic soils in its native range in Central America and Mexico. However, it can also grow on sandy, clay, and limestone soils.

Uses

G. sepium was spread from its native range throughout the tropics to shade plantation crops such as coffee. Today it is used for many other purposes including live fencing, fodder, firewood, green manure, intercropping, and rat poison. Its use expanded following the widespread defoliation of Leucaena by psyllid in the 1980s.

Fodder

G. sepium is used as cut and carry forage for cattle, sheep, and goats. Its high protein content allows it to complement low-quality tropical forages. G. Sepium can tolerate repeated cutting, every 2 to 4 months depending on the climate. Cutting G. Sepium causes it to retain its leaves during the dry season when many forage crops have lost their leaves. In some cases it is the only source of feed during the dry season.

Intercropping

G. sepium trees are used for intercropping in part because they fix nitrogen in the soil and tolerate low soil fertility, so when they are interplanted with crops they can boost crop yields significantly, without the need of chemical fertilizers.

G. Sepium tolerates being cut back to crop height, and can even be coppiced, year after year. When the trees are cut back, they enter a temporary dormant state during which their root systems do not compete for nutrients needed by the crops, so the crops can establish themselves.

These properties also enable G. Sepium to be used as green manure.

Soil Stabilization

G. sepium is a fast-growing ruderal species that takes advantage of slash and burn practices in its native range. Because it is easily propagated and grows quickly, it is also planted to prevent topsoil erosion in the initial stages of reforesting denuded areas, and as an intermediate step to be taken before introducing species that take longer to grow.

Other

G. sepium is also used for its medicinal and insect repellent properties. Farmers in Latin America often wash their livestock with a paste made of crushed G. sepium leaves to ward off torsalos (botflies). In the Philippines, the extract obtained from its leaves is used to remove external parasites.

Limitations

G. sepium seems to be toxic to non-ruminants.

Some palatability challenges have been reported; animals seem to refuse the leaves on the basis of smell, but this depends on management and geography.

Another limitation is frost intolerance and the lack of adaptation to a cool season: it is a tropical plant.

In terms of cultivation, it requires the presence of pollinators, and it needs a dry season to germinate.

Further, it has invasive potential: its swift propagation has caused it to be considered a weed in Jamaica.

Until now G. sepium has remained free of serious diseases; only a number of insect problems are reported in exotic environments, but there are issues with defoliation under humid conditions.