''Maerua angolensis'' is a 10m tall, occasionally deciduous tree of the

Capparaceae The Capparaceae (or Capparidaceae), commonly known as the caper family, are a family of plants in the order Brassicales. As currently circumscribed, the family contains 15 genera and about 430 species. The largest genera are ''Capparis'' (about 1 ...

caper ''Capparis spinosa'', the caper bush, also called Flinders rose, is a perennial plant that bears rounded, fleshy leaves and large white to pinkish-white flowers. The taxonomic status of the species is controversial and unsettled. Species with ...

family, often growing on

termitaria Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...

and in thickets fringing seasonal watercourses, up to 1800m. Though never common, it is widespread in tropical Africa and arid regions, being absent from high-rainfall regions.

Description

The tree has a rounded crown and smooth grey bark flaking to reveal yellowish-orange patches. As with most species in the family the twigs and branches display prominent

lenticels A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of gymnosperms and dicotyledonous flowering plants. It functions as a pore ...

. Leaves are soft and drooping, with petioles equal to the leaves in length, and visibly thicker or inspissate at their extremities. Leaves are alternate and broadly elliptic to ovate, with rounded or notched apex and a terminal bristle (mucronate). Leaf surfaces are often noticeably scratched by their rubbing against the bristles of surrounding leaves. The species is variable as regards pubescence, ranging from entirely glabrous to pubescent on stems and leaves. The fragrant, pincushion-like flowers are without petals and are produced in abundance at the beginning of the rainy season. Filaments are numerous (c.50) and long, initially pale yellow then turning darker with age. The 4 calyx segments recurve on opening, and the base is fringed with hairs. The distinctive torulose fruit is a

silique A silique or siliqua (plural ''siliques'' or ''siliquae'') is a type of fruit (seed capsule) having two fused carpels with the length being more than three times the width. When the length is less than three times the width of the dried fruit ...

and resembles a string of beads some 150mm in length. A slender, taller version of this species growing in the

Socotra Socotra, locally known as Saqatri, is a Yemeni island in the Indian Ocean. Situated between the Guardafui Channel and the Arabian Sea, it lies near major shipping routes. Socotra is the largest of the six islands in the Socotra archipelago as ...

archipelago,

Somalia Somalia, officially the Federal Republic of Somalia, is the easternmost country in continental Africa. The country is located in the Horn of Africa and is bordered by Ethiopia to the west, Djibouti to the northwest, Kenya to the southwest, th ...

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

and

Yemen Yemen, officially the Republic of Yemen, is a country in West Asia. Located in South Arabia, southern Arabia, it borders Saudi Arabia to Saudi Arabia–Yemen border, the north, Oman to Oman–Yemen border, the northeast, the south-eastern part ...

has been named ''Maerua angolensis subsp. socotrana'' (Schweinf. ex Balf. f.) Kers. ''M. angolensis'' is similar to ''M. schinzii'' Pax. from Namibia, which has thicker, almost fleshy leaves and other relatively trivial differences. The wood of this species is whitish-yellow, hard, dense and fine-grained, with a tendency to separate into concentric shells along the annual rings.

Distribution

It is found in

Burkina Faso Burkina Faso is a landlocked country in West Africa, bordered by Mali to the northwest, Niger to the northeast, Benin to the southeast, Togo and Ghana to the south, and Ivory Coast to the southwest. It covers an area of 274,223 km2 (105,87 ...

Burundi Burundi, officially the Republic of Burundi, is a landlocked country in East Africa. It is located in the Great Rift Valley at the junction between the African Great Lakes region and Southeast Africa, with a population of over 14 million peop ...

Cameroon Cameroon, officially the Republic of Cameroon, is a country in Central Africa. It shares boundaries with Nigeria to the west and north, Chad to the northeast, the Central African Republic to the east, and Equatorial Guinea, Gabon, and the R ...

Chad Chad, officially the Republic of Chad, is a landlocked country at the crossroads of North Africa, North and Central Africa. It is bordered by Libya to Chad–Libya border, the north, Sudan to Chad–Sudan border, the east, the Central Afric ...

Eritrea Eritrea, officially the State of Eritrea, is a country in the Horn of Africa region of East Africa, with its capital and largest city being Asmara. It is bordered by Ethiopia in the Eritrea–Ethiopia border, south, Sudan in the west, and Dj ...

The Gambia The Gambia, officially the Republic of The Gambia, is a country in West Africa. Geographically, The Gambia is the List of African countries by area, smallest country in continental Africa; it is surrounded by Senegal on all sides except for ...

Ghana Ghana, officially the Republic of Ghana, is a country in West Africa. It is situated along the Gulf of Guinea and the Atlantic Ocean to the south, and shares borders with Côte d’Ivoire to the west, Burkina Faso to the north, and Togo to t ...

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

Mali Mali, officially the Republic of Mali, is a landlocked country in West Africa. It is the List of African countries by area, eighth-largest country in Africa, with an area of over . The country is bordered to the north by Algeria, to the east b ...

Mauritania Mauritania, officially the Islamic Republic of Mauritania, is a sovereign country in Maghreb, Northwest Africa. It is bordered by the Atlantic Ocean to the west, Western Sahara to Mauritania–Western Sahara border, the north and northwest, ...

Niger Niger, officially the Republic of the Niger, is a landlocked country in West Africa. It is a unitary state Geography of Niger#Political geography, bordered by Libya to the Libya–Niger border, north-east, Chad to the Chad–Niger border, east ...

Nigeria Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea in the Atlantic Ocean to the south. It covers an area of . With Demographics of Nigeria, ...

Rwanda Rwanda, officially the Republic of Rwanda, is a landlocked country in the Great Rift Valley of East Africa, where the African Great Lakes region and Southeast Africa converge. Located a few degrees south of the Equator, Rwanda is bordered by ...

Senegal Senegal, officially the Republic of Senegal, is the westernmost country in West Africa, situated on the Atlantic Ocean coastline. It borders Mauritania to Mauritania–Senegal border, the north, Mali to Mali–Senegal border, the east, Guinea t ...

Sudan Sudan, officially the Republic of the Sudan, is a country in Northeast Africa. It borders the Central African Republic to the southwest, Chad to the west, Libya to the northwest, Egypt to the north, the Red Sea to the east, Eritrea and Ethiopi ...

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

Togo Togo, officially the Togolese Republic, is a country in West Africa. It is bordered by Ghana to Ghana–Togo border, the west, Benin to Benin–Togo border, the east and Burkina Faso to Burkina Faso–Togo border, the north. It is one of the le ...

Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...

, extending southwards into

Angola Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...

Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...

Caprivi Strip The Caprivi Strip, also known simply as Caprivi, is a geographic salient protruding from the northeastern corner of Namibia. It is bordered by Botswana to the south and Angola and Zambia to the north. Namibia, Botswana and Zambia meet at a sing ...

Eswatini Eswatini, formally the Kingdom of Eswatini, also known by its former official names Swaziland and the Kingdom of Swaziland, is a landlocked country in Southern Africa. It is bordered by South Africa on all sides except the northeast, where i ...

Malawi Malawi, officially the Republic of Malawi, is a landlocked country in Southeastern Africa. It is bordered by Zambia to the west, Tanzania to the north and northeast, and Mozambique to the east, south, and southwest. Malawi spans over and ...

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

Zambia Zambia, officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa. It is typically referred to being in South-Central Africa or Southern Africa. It is bor ...

and

Zimbabwe file:Zimbabwe, relief map.jpg, upright=1.22, Zimbabwe, relief map Zimbabwe, officially the Republic of Zimbabwe, is a landlocked country in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Bots ...

. The genus comprises some 57 species, mostly in tropical Africa, but also extending into the

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

and tropical Asia.

Subspecies and varieties

Four subspecies and varieties are accepted: *''Maerua angolensis'' var. ''africana'' – eastern Ethiopia, Somalia, and northern

*''Maerua angolensis'' subsp. ''angolensis'' – tropical and southern Africa from Senegal to Somalia and south to Angola and

Kwazulu-Natal KwaZulu-Natal (, also referred to as KZN) is a Provinces of South Africa, province of South Africa that was created in 1994 when the government merged the Zulu people, Zulu bantustan of KwaZulu ("Place of the Zulu" in Zulu language, Zulu) and ...

*''Maerua angolensis'' var. ''heterophylla'' – Angola *''Maerua angolensis'' subsp. ''socotrana'' –

Uses

Despite their unpleasant, bitter taste, the leaves are used by African rural tribes during famine periods as a

food supplement A dietary supplement is a manufactured product intended to supplement a person's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources, or that are synthetic ( ...

, and also used as a purgative. Powdered leaves are used as a fish poison and to treat anorexia and

asthenia Weakness is a symptom of many different medical conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, ...

, while bark extracts and pulped leaves are used to promote the healing of wounds. Decoctions of the leaves are given to children suffering

amoebic dysentery Amoebiasis, or amoebic dysentery, is an infection of the intestines caused by a parasitic amoeba '' Entamoeba histolytica''. Amoebiasis can be present with no, mild, or severe symptoms. Symptoms may include lethargy, loss of weight, coloni ...

jaundice Jaundice, also known as icterus, is a yellowish or, less frequently, greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving ...

, and to treat rheumatism, stomach-ache, epilepsy and diarrhoea, while decoctions of the bark are used to treat malaria and as an aphrodisiac. Game and livestock readily browse the foliage. This species, in common with other members of the family, is host to butterflies of the family

Pieridae The Pieridae are a large family (biology), family of butterflies with about 76 genera containing about 1,100 species, mostly from Afrotropical realm, tropical Africa and Indomalayan realm, tropical Asia with some varieties in the more northern ...

. Instar larvae may defoliate a tree completely, but leaves regrow readily. Phytochemical analysis of the bark revealed

glycosides In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

terpenes Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

saponin Saponins (Latin ''sapon'', 'soap' + ''-in'', 'one of') are bitter-tasting, usually toxic plant-derived secondary metabolites. They are organic chemicals that become foamy when agitated in water and have high molecular weight. They are present ...

s, carbohydrates, proteins, alkaloids and other constituents. Further studies suggested that the bark is non-toxic in anti-inflammatory doses, supporting ethnomedical use of the plant in managing inflammation.

References

Citations

Prodr. 1: 254 (1824) — Sim, For. Fl. Port. E. Afr.: 10 (1909). — Gilg & Bened. in Engl., Bot. Jahrb. 53: 257 (1915). — Burtt Davy, F.P.F.T. 1: 122 (1926). — Steedman, Trees etc. S. Rhod. 9 (1933). — Arwidss. in Bot. Notis. 1935: 360 (1936). — Exell & Mendonça, C.F.A. 1: 59 (1937). — Hauman & Wilczek, F.C.B. 2: 487 (1951). — O. B. Mill. in Journ. S. Afr. Bot. 18: 16 (1952). — Milne-Redh. in Mem. N.Y.Bot. Gard. 8 3: 217 (1953). TAB. 35 fig. F. Type from Angola.

External links

'Flora of Zambia' gallery

Slashed trunk

Longitudinal section of fruit
* {{Taxonbar, from=Q15127254

angolensis This list of Latin and Greek words commonly used in systematic names is intended to help those unfamiliar with classical languages to understand and remember the scientific names of organisms. The binomial nomenclature used for animals and plants ...

Flora of the Afrotropical realm Plants described in 1824 Taxa named by Augustin Pyramus de Candolle