‘Efor’ as the Ewes of the Volta Region of Ghana call it, African black plum is the fruit produced by a tree botanically named Vitex doniana. Names of the fruit among other ethnic groups in Ghana include ‘sho’ (Ga people in Greater Accra), ‘efuaa’ (Fantes), ‘ngmariba’ (Dagombas in Northern Region), ‘apusibi’ (Gonjas in Northern Region) and ‘haraa’ (Waala people of the Upper West Region). You may indicate the name of the fruit in your language at the Comments column.

This write-up briefly explains the nomenclature and taxonomy (how both the common and the botanical names were derived). Further, it provides some botanical, agronomic and ecological information on the species. The African black plum is one of the trees/fruits that are misnamed black berry in Ghana. Because plums /plams/ are drupes, and not berries, the term black berry is absolutely erroneous when used to name the fruit of Vitex doniana.

Typical of most common or trivial names, ‘African black plum’ is merely descriptive with all the words needing to be present to identify the plant uniquely. In the name, the word ‘African’ tells the origin of the tree, ‘black’ describes the colour of the ripe fruit and ‘plum’ shows the type of fruit. Some sources precede the toponym ‘African’ with ‘wild’ or ‘West’: ‘wild’ shows that the plant is undomesticated, while ‘West’ refers to the predominance of the trees in West Africa. Adding or dropping either of these words still leaves the name correct.

Both the immature and mature but unripe fruits are green; they turn completely black when ripe. The black colour is confined to only the first two layers of the fruit—the epicarp (outermost layer) and mesocarp (the inner or second layer). The epicarp is a shiny, thin skinny layer that is easily peeled off to expose the mesocarp—the edible part. The mesocarp contains a completely black non-juicy pulp (See photo. In case Ghanaweb does not publish the photo, you may logon to http://www.spyghana.com/efor-west-african-black-plum/ where the photo is clearly displayed.)

When eaten, the mesocarp temporarily blackens the teeth. The black colour of the epicarp and mesocarp and their subsequent blackening of the mouth led many people to mistakenly call the fruit black berry. When extracted and washed thoroughly, the seed is seen surrounded by a tough, thick woody endocarp that is light brown to grey in colour (see photo attached). This thick woody endocarp or shell is the innermost layer of the fruit.

The presence of the hard endocarp/shell enclosing the seed is the distinctive feature showing that the plums are drupes and not berries (see the next write-up: Drupes and berries differentiated). African black plums are clingstones (drupes whose seeds or pits or stones are strongly attached to the flesh). The black mesocarp strongly adheres to the endocarp surrounding the seed. Being drupes, African black plums should never be confused with black berries (Rubus spp.) which are true berries that are also coloured black.

Taxonomically, the genus name Vitex /vaiteks/ was coined by Linnaeus in 1753. Seeing the flexible twigs of another species (called Vitex agnus-castus) used to weave baskets, the Swedish naturalist coined the term ‘vitex’ from the Latin word ‘vieo’ meaning to weave or to tie up. Formerly placed in the family Verbanaceae, Vitex was transferred to Lamiaceae in the 1990s when phylogenetic studies on its DNA sequences reveal its close relationship with other lamiaceous species (Bramley et al., 2009).

The genus Vitex comprises several species of trees and shrubs. The specific tree called African black plum was named botanically and described validly by the English botanist Robert Sweet in 1826. Technically, the scientist who validly describes and/or names a species usually has his or her name (or recognized author abbreviation) attached to the scientific name of the said organism. This author citation is usually done only once in any given write-up at the first mention of the scientific name. Hence, the full botanical name of African black plum is Vitex doniana Sweet, with ‘Sweet’ honouring the aforementioned English botanist. (Notice that the author’s name or abbreviation is never italicized or underlined.)

Ecologically, Vitex doniana is a medium-sized deciduous tree up to 8–20 m growing wild in coastal woodlands and savannahs including most wet (secondary) forests. In the dry savannah regions, African black plum trees grow in places where the water table is high. Older leaves abscise during the dry season and new leaves are produced just before the onset of rains.

The fresh or immature leaves serve as an important leafy vegetable; they are used as thickeners in soup. More importantly, they are boiled and rolled into balls which are salted and eaten as whole meal or mixed with ‘koose’ (bean cake). Among the Waala people, the boiled leaves are termed ‘jenjega’. The availability of the leaves during the beginning of the farming season—lean season—makes V. doniana one of the major life-sustaining species in the savannah regions of sub-Saharan Africa. More research is therefore required to domesticate the tree.

Using its preference for areas with high water table, indigenous people sunk shallow wells easily in such areas. V. doniana also produces large quantities of nectar; hence, apiarists (beekeepers) often site beehives under them. The ellipsoid to oblong fruit measuring 2–3 cm long are edible. V. doniana is one of the few non-leguminous nitrogen-fixing plants enriching the soil through annual leaf fall.

Agronomically, Vitex doniana seeds like other drupes such as oil palm are exogenously dormant. The exogenous dormancy is imposed on the embryo by the surrounding thick endocarp. (The endocarp and seed measures 1–1.4 cm, while the enclosed seed measures from 0.3–0.4 cm. Thus, much of the dispersed unit is the thick, woody endocarp). To hasten germination, you may scarify seeds by soaking in concentrated sulfuric acid (95 %) or by rubbing the endocarp with a file or sandpaper. Acid scarified seeds may germinate in a month (Ky, 2008). Alternatively, freshly extracted seeds are sown after overnight soaking in water.

Comparing African black plum to other plums such as the European plum (Prunus spp.), Ashanti plum (Spondias mombin), blood plum (Haemostaphis barteri) and monkey plum (Ximenia spp.); we notice that the only similarity among them is their production of drupaceous fruits termed plums. Botanically, all these plums are unrelated. Therefore, common or English names of plants were mostly coined based on their culinary (food) uses and these names often provide little agronomic or botanical info about the plants. Hence, African black plums are not black berries.

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