Iroko (Milicia excelsa) is a hardwood tree native to the west coast of tropical Africa. This tree is long-lived, it can live up to 500 years.
Iroko is the common name for the genus Milicia, in which there are two well-known and closely related species, namely Milicia excelsa and Milicia regia.
This tree is known as ìrókò, logo, or loko by the Yoruba people and is believed to have healing properties. Igbo people call iroko oji. This tree is also known as uloho by the Urhobo people of Nigeria and odum by the Kwa people of Ghana.
Iroko is a wood-producing tree that is sometimes referred to as African Teak. The color of the wood is initially yellow but over time it becomes darker and eventually becomes copper brown.
Iroko is mostly produced from the species Milicia excelsa. In the literature on wood, the names of the trees that produce it are given as Chlorophora excelsa syn Milicia excelsa and Chlorophora regia syn Milicia regia.
The large number of iroko trees that are felled each year means that the future trade in this wood is considered highly endangered. Currently, the IUCN Redlist has classified the Milicia excelsa or Iroko tree as Near Threatened (NT).
Yoruba people, even if they need to cut down an iroko tree, can pray afterward to protect themselves.
Characteristics of Iroko Leaf
The leaves have visible rectangular veins on the underside. The branches are thick in the crown, all horizontal to form an umbrella. Smaller branches hang down on female trees and curve upward on male trees. The bark of the branches is pale or dark grey, thick but slightly fissured, and if damaged will ooze a milky fluid.
Characteristics of the Iroko Flower
Female trees have catkins-sized flower spikes. Male trees are dioecious, 5 to 10 cm long, oval or elliptical with finely serrated edges, green and smooth on the top and slightly hairy on the bottom.
Flowering occurs at different timescales but often occurs in January and February immediately after most of the leaves have fallen or just before new leaves appear.
Characteristics of Iroko Fruit
The fruit is long, wrinkled, and fleshy with small seeds embedded in the flesh.
The fruit takes about a month to ripen and is favored by squirrels, bats, and birds, who then spread the seeds in their droppings. These seeds also germinate better than uneaten seeds and last longer.
Characteristics of Iroko Tree
Iroko is a large tree that can grow 30-40 meters high. This tree can be found in many countries in central and eastern Africa, especially Angola, Benin, Burundi, Cameroon, Central African Republic, Congo, Ivory Coast, Equatorial Guinea, Ethiopia, Gabon, Ghana, Kenya, Malawi, Mozambique, Nigeria, Rwanda, Sierra Leone, Sudan, Tanzania, Togo, Uganda and Zimbabwe.
The trunk is bare at the bottom with the first branch usually at least 20 meters above the ground. Often has several short supporting roots at the base.
The original habitat of the iroko tree is in wet savannas, rainforests, river banks, and green forests in the lowlands. This tree is drought tolerant for six months as long as there is a river or groundwater source nearby.
Many studies link this growth variation to climate differences between regions. In particular, soil characteristics and rainfall play a major role in the variation in the growth morphology of Milicia excelsa.
Benefits of Iroko Tree
The bark powder is used to treat coughs, heart problems, and lethargy. Latex is used as an anti-tumor agent and to clear gastric and throat obstructions. The leaves and ash also have medicinal uses.
The wood is excellent for interior and exterior decks. Iroko wood is selected and used for making djembe musical instruments, shipbuilding, flooring, furniture, and outdoor gates.
Iroko wood is very durable, hard, stable, and highly resistant to rot and insect attacks. This wood does not require regular maintenance with oil or varnish when used outdoors. However, it is very difficult to work with tools because the tools become dull very quickly.
Like ojoche (Brosimum alicastrum), iroko belongs to a group of 200 species of oxalogenic trees, known for their storage capacity for atmospheric CO2 in the form of oxalate which is converted to calcium carbonate. This fixation of mineral salts may explain the hardness of the wood and the difficulty of cutting it. Iroko is the object of study of the European Biomimicry program which plants oxalogenic vegetation in Haiti, India, and Colombia.