''Portulacaria afra'' (known as elephant bush, porkbush, purslane tree and ' in
Afrikaans
Afrikaans (, ) is a West Germanic language that evolved in the Dutch Cape Colony from the Dutch vernacular of Holland proper (i.e., the Hollandic dialect) used by Dutch, French, and German settlers and their enslaved people. Afrikaans gra ...
) is a small-leaved
succulent plant
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...
found in
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
. These succulents commonly have a reddish stem and
leaves
A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
that are green, but also a variegated
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
is often seen in cultivation. They are simple to care for and make easy houseplants for a sunny location. In frost-free regions they may be used in outdoor landscaping.
Description
It is a soft-wooded, semi-evergreen upright shrub or small tree, usually tall. It is sometimes confused with ''
Crassula ovata
''Crassula ovata'', commonly known as jade plant, lucky plant, money plant or money tree, is a succulent plant with small pink or white flowers that is native to the KwaZulu-Natal and Eastern Cape provinces of South Africa, and Mozambique; i ...
'' (Jade plant), which it is not closely related to. ''P. afra'' has smaller and rounder pads and more compact growth (shorter internodal spaces, down to ). It is much hardier, faster growing, more loosely branched, and has more limber tapering branches than ''Crassula'' once established.
The genus ''
Portulacaria
''Portulacaria'' is a genus of succulent plant, classified in its own subfamily Portulacarioideae in the family Didiereaceae. It is indigenous to southern Africa.
Taxonomy
The genus was previously placed in the family Portulacaceae, but accordi ...
'' has been shown to be an outlier, relatively unrelated to the other genera in the family, which are all restricted to small ranges in the arid far west of
Southern Africa
Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of ...
.
Distribution and habitat
It is very widespread in the east of
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
(as well as
Eswatini
Eswatini ( ; ss, eSwatini ), officially the Kingdom of Eswatini and formerly named Swaziland ( ; officially renamed in 2018), is a landlocked country in Southern Africa. It is bordered by Mozambique to its northeast and South Africa to its no ...
). In this moist climate, it is relatively rare, and tends to favour dryer rocky outcrops and slopes.
It is also found in much denser numbers in the dryer southern Cape. Here it occurs from the
Little Karoo
The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe !Orakobab or Khoemana word ''ǃ’Aukarob'' "Hard veld") is a semi- desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its ...
of the
Western Cape
The Western Cape is a province of South Africa, situated on the south-western coast of the country. It is the fourth largest of the nine provinces with an area of , and the third most populous, with an estimated 7 million inhabitants in 2020 ...
, eastwards up until the
thicket
A thicket is a very dense stand of trees or tall shrubs, often dominated by only one or a few species, to the exclusion of all others. They may be formed by species that shed large numbers of highly viable seeds that are able to germinate in t ...
vegetation of the
Eastern Cape
The Eastern Cape is one of the provinces of South Africa. Its capital is Bhisho, but its two largest cities are East London and Gqeberha.
The second largest province in the country (at 168,966 km2) after Northern Cape, it was formed in ...
.
Spekboom is found most prolifically in the
Albany thickets, a woodland
ecoregion
An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
, which locally is often called ', after the high number of succulent ''
Euphorbia
''Euphorbia'' is a very large and diverse genus of flowering plants, commonly called spurge, in the family Euphorbiaceae. "Euphorbia" is sometimes used in ordinary English to collectively refer to all members of Euphorbiaceae (in deference to t ...
'' species, which are often called ' plants. In these environments, ''P. afra'' is a source of food for multiple large herbivores, such as the
Black rhinoceros
The black rhinoceros, black rhino or hook-lipped rhinoceros (''Diceros bicornis'') is a species of rhinoceros, native to eastern and southern Africa including Angola, Botswana, Kenya, Malawi, Mozambique, Namibia, South Africa, Eswatini, Tanzania ...
and the
African elephant.
Although it is not the primary food source for these animals, it still makes up a significant portion of their diet.
Cultivation and uses
In the wilds of South Africa, large plants do survive the winter frosts by growing dense enough to provide their own natural cover. Drought-tolerant and fire-resistant, it will endure desert sun and heat once established, which the jade plant will not. ''P. afra'' is a common landscape plant in Phoenix, Arizona, and southern California, growing i
USDA plant hardiness zones9-11.
Cuttings root very easily in most potting media.
Ornamental
It is popular as a specimen for bonsai,
and as a hardy
xeriscaping
Xeriscaping is the process of Garden design, landscaping, or gardening, that reduces or eliminates the need for irrigation. It is promoted in regions that do not have accessible, plentiful, or reliable supplies of fresh water and has gained accep ...
plant.
Several varieties exist - some bred in cultivation, others naturally occurring:
* "Limpopo": A variety with much larger leaves. It is the natural form from the far north of the species' range.
* "Prostrata": A low-lying, decumbent form that is frequently used as a ground-cover.
* "Aurea": A compact, upright form with rounded leaves that go bright yellow in the sun.
* "Foliis variegatus": A variegated form.
* "Medio-picta": Variegated with a lighter centre.
Food source
In Southern Africa it is commonly eaten, usually as one component of a salad or a soup. It should not be confused with the
jade plant
''Crassula ovata'', commonly known as jade plant, lucky plant, money plant or money tree, is a succulent plant with small pink or white flowers that is native to the KwaZulu-Natal and Eastern Cape provinces of South Africa, and Mozambique; i ...
, which is mildly toxic.
''P. afra'' is also used to feed livestock during periods of drought due to its
succulent
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...
nature.
Most commonly used for cattle and goats, these plants also act as a supplemental source of water on top of their nutritional benefits for livestock.
Medicinal
This is one of the many plants used as a traditional treatment for skin conditions used by people in rural areas that do not have easy access to more modern medicine.
Carbon sequestration and ecological impact
''P. afra'' is capable of either
or
CAM
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...
carbon fixation
Biological carbon fixation or сarbon assimilation is the process by which inorganic carbon (particularly in the form of carbon dioxide) is converted to organic compounds by living organisms. The compounds are then used to store energy and as ...
, depending on factors such as the season and the age of the leaves.
In the dry season, it relies on the
CAM
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...
pathway due to the lack of water, but when water is reintroduced, the plant quickly reverts to the
C3 pathway in order to conserve energy. The maturity of the leaf tissue also matters because younger tissue is unable to completely seal the stomata, making
CAM
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...
impossible. So while the older leaves are able to switch pathways based on the season and conditions, the younger leaves have to rely solely on the
C3 pathway. It can sequester a maximum of 15.4 t CO
2 ha
−1yr
−1.
The South African government's Working for Ecosystems programme proposes restoring a million hectares (2.5 million acres) of ''P. afra'' thicket.
The addition of more spekboom into the environment can also help restore native species to areas where they no longer can grow.
P. afra has been shown to help create shade and add organic material into sandy soil, which allows for an environment more hospitable to young plants, thus helping restore populations of native species that were reduced by
overgrazing
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature res ...
and
desertification
Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid. It is the spread of arid areas caused by ...
.
References
Further reading
*
{{Taxonbar, from=Q2481534
afra
Endemic flora of South Africa
Garden plants of Africa
Drought-tolerant plants
House plants
Plants used in bonsai
Albany thickets