Leucaena leucocephala is a small evergreen tree or shrub that grows 15 to 20m tall in favorable conditions. The trunk is woody, cylindrical, and branched with gray-brown to rusty-orange bark.
It is easily recognizable by its long linear-oblong flat seed pods that are initially green but turn brown when mature.
Leucaena leucocephala Classification
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Fabales
- Family: Fabaceae
- Genus: Leucaena
- Species: Leucaena leucocephala
- Varieties: Leucaena leucocephala var. leucocephala, Leucaena leucocephala var. glabrata, and Leucaena leucocephala var. ixtahuacana
- Common Names: Leucaena, Horse tamarind, White leadtree, Coffee bush, White popinac, White papinac, Jumbay, Jumpy bean, Hedge acacia, Ipel-ipel, Ipil, Tan-tan, False koa, and Subabul.
Nativity and Distribution
Leucaena leucocephala is native to Mexico while other sources cite its nativity to Guatemala and Belize. Today, the River tamarind tree can also be found in parts of:
- Africa
- Asia
- Oceania
- North America
- And throughout Central and Southern America
Physical Characteristics
- Leaves: Bipinnate, alternate with 4-10 pairs of pinnae per leaf.
- Fruits: Orange-brown flat pods.
- Stems: Woody trunk. It can grow between 5-20m tall.
- Flowers: Small, white to cream-colored flowerheads with hairy anthers.
- Roots: Deep and highly branched taproot.
Leucaena leucocephala is a small fast-growing tree or shrub that can grow up to 20m in favorable conditions. It is easily recognizable by its long straight green flat pods with papery walls that turn brown when mature.
The trunk is woody, upright, about 35-50 cm wide. It can grow as a shrub about 3-5m tall or grow into a small or medium-sized tree about 15m with older trees growing to a height of 20m tall. As a tree, it has a vertically-grooved bark with a short clear bole up to 5 m and then heavily branches upwards.
The leaves are bipinnate with 4-9 pairs of pinnae per leaf and numerous linear oblong leaflets 2-5 mm wide and 8-21 mm long. The leaflets are rounded at the base, glabrous except on the margins, and acute at the tip.
River tamarind produces small white to cream-colored flowers about 12-21 mm in diameter with hairy anthers that grow concurrently with the leaves. Flowering mostly occurs in the spring and summer. The flowers produce dehiscent papery pods that contain 15-30 seeds.
The seeds are ovoid, brown, and flat, about 4-6mm wide and 6-10mm long.
Reproduction, Dispersal, and Life Cycle
- Life Cycle: Perennial.
- Seeds: Produces 4,000-8,000 seeds per year.
- Climate: Tropical climate in hot and humid conditions.
- Dispersal: Water, wind, animals, and contaminated machinery.
Leucaena leucocephala behaves as a perennial and reproduces by seeds. A single plant produces 4,000-8,000 seeds in one year.
When mature, the seed pods open and release the seeds. They are mainly dispersed by wind, animals, and water. They can also be moved long distances by agricultural tools and machinery.
The seeds germinate quickly up to a depth of 1 cm below the surface. However, the majority of the seeds can remain viable for 1-20 years.
Similar Plants
- Acaciella glauca
- Acaciella angustissima
- Acacia frondosa
Uses
- Ipil-ipil is a valuable fodder crop for livestock because of its high crude protein and palatability.
- It is sold as leaf meal feed for poultry and pigs in Asia.
- The unripe pods and seeds are an important source of food throughout Mexico and parts of Asia.
- The leaves are used as green manure in cropping systems.
- It is used for soil improvement and soil erosion control.
- It is used in land rehabilitation and revegetation.
- It is used as support for passion, vanilla, and pepper vines.
- The dried seeds are worn as beads.
- The seed extracts are used to make traditional medicine to treat colds, fevers, back pain, and circulatory problems in Indonesia and the Lucayan Archipelago.
- The wood trunk is used to make furniture, parquet flooring, and small dimension poles.
- The wood is also used as domestic and industrial fuel.
- The pod, leaf, and bark extracts are used to make black, red, and brown dyes.
Impact of Farms and Environment
Leucaena provides many benefits for farmlands, including nitrogen fixation, soil conservation, and erosion control in agroforestry landscapes.
It’s also an important fodder crop for livestock and is often described as the “alfalfa of the tropics” for its high (70-100%) animal live weight gain compared to grass pastures.
Its leaf litter provides a quick nutrient fixation that improves soil fertility, leading to higher yields. It also provides shade and creates boundaries and windbreaks in horticultural farms for improved yields.
Despite these benefits, L. leucocephala can become toxic (due to its mimosine content) to livestock if added to more than 30% of the diet.
Additionally, it can become weedy in abandoned pasture lands, posing a costly eradication problem if it spreads to croplands.
Ipil-ipil is a known habitat transformer. If not managed, it can outcompete native species and colonize large areas by forming dense thickets, negatively impacting biodiversity. It has degraded local plant species in countries like Hawaii, Ghana, and Brazil, preventing native forest regeneration in Guam and Mauritius.
Control
- Mechanical control: Cutting, digging, and pulling.
- Cultural control: Grazing and solarization.
- Chemical control: Herbicides like triclopyr, 2,4-D, tebuthiuron, and trunk glyphosate injections.
Mechanical cutting and pulling out the entire root system are viable for small plants. The combination of cutting and herbicide application can help eradicate older trees. Cutting down the trees and covering the stumps with a thick black plastic sheet can kill seedlings and limit stump regrowth.
Since it’s a highly nutritive and palatable pasture, grazing cattle and goats can help prevent the weed from becoming invasive.
Chemical herbicides like triclopyr have been found effective if applied on active foliage. When combined with cutting, triclopyr ester and picloram can provide effective Ipil-ipil control. Additionally, glyphosate injections into the tree stump during the dry season have been shown to reduce resprouting.
Always read the herbicide label and follow the application instructions for the best results.
Lead Editor for Insight Weeds.