Bitterwood Tree
Picrasma
A genus of deciduous trees and shrubs known for their extremely bitter bark and medicinal …
Hannoa ferruginea is a medium-sized deciduous tree native to the upland woodlands and rocky savannas of tropical Africa. Its specific epithet ferruginea means "rust-colored" in Latin, pointing directly to the dense, velvety coat of reddish-brown hairs that blankets its young branches, leaf stalks, and flower buds.
Originally described by the German botanist Adolf Engler in 1902, the genus Hannoa was named after Hanno the Navigator, the ancient Carthaginian explorer of the West African coast. In modern taxonomic databases such as Plants of the World Online (POWO), this taxon is treated as a heterotypic synonym of the widespread African species Quassia undulata (also widely recorded in regional floras as Pierreodendron or Hannoa undulata).
In its native savanna and woodland habitats, the tree typically grows between 6 and 15 meters tall, developing a rounded, somewhat open crown. The trunk is covered in thick, corky, greyish-brown bark marked by deep longitudinal fissures that insulate the living cambium from seasonal grass fires.
The foliage consists of large, imparipinnate leaves — compound blades arranged like a feather with a single terminal leaflet at the apex. Each leaf bears several pairs of leathery, oblong to elliptic leaflets with distinctly wavy margins and long petiolules (the slender stalks attaching individual leaflets to the main central axis, or rachis).
The tree produces broad, branched terminal panicles — loose, pyramid-shaped clusters of small, fragrant, yellowish-white to greenish-cream flowers. Following pollination, the fertilized carpels develop into oblong, plum-like fleshy drupes (stone fruits) that turn dark purplish-black at maturity, each enclosing a single hard, woody endocarp.
Dry season and early transitions into the wet season, typically from November to March depending on latitude
In West and Central African ethnomedicine, bitter decoctions prepared from the stem bark and roots of this tree (under the name Hannoa ferruginea or Quassia undulata) are traditionally used by local healers to treat malarial fevers and gastrointestinal ailments. Phytochemical researchers also study its wood and bark extracts in laboratory settings to isolate bioactive quassinoids — oxygenated triterpene lactones investigated for their antiprotozoal and cytotoxic properties.
Because the pale, yellowish-white timber is relatively soft, lightweight, and easy to carve without splitting, rural artisans occasionally harvest the wood to fashion household utensils, stools, and light construction poles.
Surviving in tropical African savannas requires a plant to solve two opposing environmental problems at once: intense dry-season solar radiation combined with seasonal bushfires, and heavy browsing pressure from insects and herbivores when fresh foliage flushes after the rains. Hannoa ferruginea addresses both challenges through a coordinated combination of physical micro-insulation and internal chemical deterrence.
Picrasma
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