Pentaclethra macroloba - Oil Tree

Pentaclethra macroloba - Oil Tree - Fabaceae

Pentaclethra macroloba, or Oil Tree, is a large evergreen tree native occurring in nature from Nicaragua to Amazonia. In the rainforest, it is most often the dominant species of tree, where it will reach from 100-115 feet (30-35 m) tall. The biparipinnate leaves will reach up to 12 inches (30 cm) long and have a feathery appearance. The bark is smooth, grey-brown in color. The seeds of the tree have a very high oil content, which is used to make lubricants and soaps. Although they are very large trees, their size is easily controlled with container size and selective pruning. Our plants at 10 years old have only reached about 10 feet (3 m) tall in 5 gallon containers. They are easy to grow.

Blooming: In the greenhouse, plants bloom in April –May. The flowers are hermaphroditic, small in terminal racemes. The racemes will reach up to 8 inches (20 cm) long. Only 4-5 flowers will produce seeds. There are up to 200 flowers per raceme.

Culture: Pentaclethra macroloba need full sun to partial shade with a moist rich soil mix. In the greenhouse we use a soil mix consisting of 2 parts peat moss to 2 parts loam to 1 part sand or perlite. The trees are native to swamps and river banks. They take a lot of water all year long. When we where growing the plants for the nitrogen fixing nodules on the roots they where fertilized with a nitrogen free Hoagland’s solution. Now that they are not used for research they are fertilized weekly with a balanced fertilizer. The winter time temperatures are never allowed to drop below 55°F (13°C). The water and fertilizer regime is carried out the same as the rest of the year.

Propagation: Pentaclethra macroloba is propagated by seed. Fresh seed will germinate in 8-10 day at 70°F (22°C). Seeds have a very short shelf life. Most seed will not germinate if over a week old.

Pentaclethra macroloba was featured as Plant of the Week August 17-23, 2007.

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Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically the late Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2017 All rights reserved.