Culture
Winter hardy to USDA Zones 11-12 where it is best grown in organically rich, well-drained soils in full sun to part shade. Intolerant of frost.
Noteworthy Characteristics
Couroupita guianensis, commonly known as cannonball tree, is a soft-wooded, deciduous tropical tree of the Brazil nut family that typically matures to 50-75’ (infrequently to 100’) tall. It is primarily native to rainforests in the Guianas (French Guiana, Suriname and Guyana) in northeastern South America, but has been widely planted in a number of different tropical to semi-tropical areas around the world. The common name is in reference to the unusual, bordering-on-the bizarre, woody, globose, hard-shelled, reddish-brown fruits of this tree which mature to a cannonball size of 8-10” in diameter. On windy days, the fruits often bang against each other on the tree creating a sound reportedly resembling a cannonade. Each fruit contains 200-300 seeds which are embedded in an ill-smelling, soft red pulp which turns bluish-green when exposed to air. Each fruit typically takes 1 year or more to mature. When ripe, fruits drop from the tree, usually splitting open as they hit the ground with an explosive splat.
Large, pleasantly fragrant, rose-pink to red flowers (each to 4-5” across) bloom in racemes. Each flower has a 6-lobed calyx and 6 spreading petals which encircle two types of stamens (fertile stamens and sterile staminoides) which are borne on a cream-colored androphore. Each individual flower blooms for only one day. Flowers and subsequent fruits are located on drooping, naked, thick, tangled, vine-like stems (extrusions to 2-6’ long) which emerge directly from the trunk and large branches. Old trees often have the lower parts of their trunks completely covered with dangling flower racemes and fruits.
Simple, elliptic to ovate to oblong leaves (6-8” long) are primarily clustered near the branch ends. Leaves are alternate or in apical whorls. Leaf margins are entire or finely serrate. Veins on leaf undersides are pubescent. Leaves typically drop once, but sometimes twice, per year, usually in response to dry weather, hence the designation of deciduous for this tropical tree.
Genus name is a modification of the name of a native tree used in Tropical America.
Specific epithet is in reference to the Guianas where this tree is native.
Problems
No serious insect or disease problems. Mature fruits release a fetid aroma when they drop to the ground and break open. Foot traffic should not be permitted under the drip-line of this tree because falling fruit can seriously injure or kill human beings. Trees grown in public places often have warning signs about falling fruit.
Uses
Plant as a curiosity in tropical gardens in areas where there will be minimal foot traffic under the tree when the ripened fruits are dropping.