Combretum is a genus of the plant family Combretaceae and contains approximately 250 species of trees and shrubs that are native to most tropical regions, except the continent of Australia. Often these plants are evergreen, though some are deciduous for a short time. Some species adapted to the areas where they grow. On rocky slopes, they may be shrubs; near the coastline, they may grow as thickets; and in woodlands, they often grow as trees. Many Combretum plants have medicinal uses, especially by native herbalists.
Most of the plants have oblong or elliptic shaped leaves that grow in pairs that are at right angles to the pair above and/or below. Some of the species have leaves that grow in whorls. Generally, the leaves are entire, meaning that they are not toothed or lobed at the edges.
The flowers are usually tubular with four or five lobes at the opening. These bell-like flowers grow in racemes or panicles on terminal stems or auxiliary stems. Many of these clusters are densely loaded with red flowers that may measure from 0.75 inch (about 2 cm) to more than 1.5 inch (about 4 cm) long. Growers often cultivate some of the Combretum species for their showy flowers.
The species C. grandiforum is an evergreen shrub or a semi-climber that responds well to having pergola or trellis support in the garden. Growers usually cultivate it for its bright red flowers that grow on a short, one-sided raceme. The shrub generally grows to a height of 12 to 20 feet (about 4 to 5 m) and 6 to 12 feet (about 2 to 4 m) across. This native of regions in west Africa, Gambia, and Ghana generally needs a warm climate with a minimum temperature of 60°F (about 16°C) to thrive.
The semi-evergreen shrub, C. paniculatum, has spiny stems and papery, broadly elliptic leaves that may measure up to 7 inches (about 18 cm) long. Its red flowers usually are 1.5 inches (4 cm) long and are grouped in a panicle. This plant from parts of tropical Africa may grow to heights of 30 feet (about 9 m) and spread to 10 to 15 feet (about 3 to 5 m) wide. Growers generally trellis the climbing varieties.
Leadwood, or C. imberbe, is a protected tree in Africa. In its native regions, it may grow to 66 feet (about 20 m) high with a canopy spread that is almost as wide. It is the largest tree in southern Africa and often grows in mixed forest and Bushveld areas, especially by waterways, lakes, and similar regions. The leadwood tree's trunk is typically pale gray to white with a snakeskin-textured bark, and the green leaves are leathery. The fragrant, creamy white to yellow flowers mature into a fruit that has four wings, which form a cross shape and change from yellowish green to red as they mature.
Some Bush tribes use the gum-like sap as a food staple. Various species of animals, including antelope, elephants, and other tree foragers, graze on mature Combretum plants. Many types of rodents eat the seeds, and livestock forage on the seedlings. Overgrazing has endangered some species, especially the leadwood tree.
Generally, people around the world use the Combretum plants. Some people use leadwood ashes for toothpaste. Most herbal remedies are used for cough and chest problems, stomach pains and diarrhea, and parasites. Pharmaceutical companies use some of the plants, called bush willows, for anti-cancer compounds, or combretastins. Most combretastins are made from the C. caffrum tree bark and reduce the blood flow to cancerous tumors.
Non-medical uses of the Combretum plants vary depending upon the region and the species. Some tribes weave immature branches and stems into the baskets, mats, and other items. Although the sawdust often is a skin irritant, people use the hard wood for furniture, walking sticks, and more. Some tribes use the root bark to tan leather.