Natural forests combat non-native tree invasions

The native biodiversity of natural forest patches like this one in the foreground play a crucial role in buffering against invasions by non-native plants and trees, while the non-native eucalypt plantation in the background provides the timber resource for countless products. Good land management is required to ensure that the non-native eucalypts fulfil their function, while the natural forest, which harbours the biodiversity that underpins a healthy landscape, needs to be carefully protected.

A new study, published recently in Nature, has found that the native biodiversity of natural forests largely buffers the severity of non-native tree invasions.

The bad news, however, is that humans remain mostly responsible for introducing non-native tree species to an area in the first place – either intentionally or accidentally.

These are two of the key findings from a global study to determine the relative importance of human activity, environmental conditions, and biological diversity as drivers of tree invasions worldwide. The study, titled “Native diversity buffers against severity of non-native tree invasions” was published in the journal Nature on Wednesday, 23 August 2023.

Prof. Cang Hui, holder of the South African research chair in mathematical and theoretical physical biosciences at Stellenbosch University (SU), and one of the co-authors of the study as part of the Global Forest Biodiversity Initiative (GFBI), says trees are exposed to a wide range of ecological and human factors, and tree invasions are both drivers and passengers of global environmental changes.

This is because of their size, long life span and important role in forestry, foraging, city landscaping and reforestation, as well as carbon sequestration and climate regulation. Yet invasion biologists have long been struggling to identify the ecological mechanisms driving the invasion success of a small portion of non-native tree species.

Their findings support the biotic resistance hypothesis, which holds that greater diversity in the native community will fill the ecological niches and reduce available resources, thereby limiting non-native species to take up niche spaces.

The prominent role of human activities, however, came as a surprise: “Our findings suggest that human activity may overwhelm ecological drivers of invasions and even reduce the influence of ecological processes,” he warns.

Three of the most frequent non-native trees in the GFBI database (left to right) Black Locust; Osage orange; Tree of Heaven (Photos courtesy iNaturalist, Dave Richardson, Rosario, and Gehardt).

Repeated human introductions of plant species, especially close to ports and airports, play an important role in the initial introduction process. The severity of the invasion, however, is predominantly a result of the intrinsic diversity of the native community.

It is therefore important to conserve natural forests to maintain high native tree diversity, they write in the paper.

Furthermore, because many tree species are introduced purposefully for forestry or to support local livelihoods, they recommend that local stakeholders are included when making decisions about how best to benefit from these managed forests.

Some of the other findings include:

Read the full article here: Delavaux et al. (2023) Native diversity buffers against severity of non-native tree invasions

New protected trees in SA

Four new species have been added to the list of trees that are protected under the National Forests Act in South Africa - the Red Ivory, Jackal Berry, Manketti and Umtiza.

The four trees were added to the Protected Trees list by the Minister of Environment, Forestry and Fisheries Barbara Creecy and published in the Government Gazette on 25th March 2022.

The list of Protected Trees includes a broad range of important indigenous trees found in diverse habitats from dense natural forests of the Cape, to woodlands and semi-arid Karoo and Namaqualand. It also includes threatened species such as the Clanwilliam Cedar, the Umtiza and the Pepper Bark tree which has been heavily harvested for muti and is now being propagated and planted out in an effort to increase its numbers in the wild.

In terms of the law anyone who cuts, disturbs, damages, destroys or interferes with any of the 53 protected trees could be convicted and sentenced to three years imprisonment, or fined or both.

"No person may cut, disturb, damage or destroy any protected tree or possess, collect, remove, transport, export, purchase, sell, donate or in any other manner acquire or dispose of any protected tree except under a license granted by the Minister," notes the gazette.

Exceptions to this law are only applicable to those who have been granted a special license or exemption by the Department.

The four new protected trees are:-

Berchemia zeyheri  aka Red Ivory or Rooihout

Red Ivory is an evergreen to semi-deciduous tree. It is drought-resistant but not frost-resistant, and usually grows in dense groups, reaching 15 metres in height. It is evergreen to semi-deciduous and is commonly found in Limpopo, where its fruit is picked and sold on the street.

Wood from the tree is used to make durable furniture, while its leaves and fruit are favoured by birds and bushbuck.

It has yellow-ish sapwood and hard, heavy heartwood. Leaves are blue-green with reddish stalks. Flowers are yellow or green-white and grow in clusters. The fruit is yellow to brown-red.

Red ivory trees occur naturally from Zimbabwe to the Eastern Cape in South Africa, and are common in Limpopo. It grows in woodland, bushveld, rocky areas, along rivers, streams and on old termite mounds. It is also found on south and east-facing mountain slopes.

The fruit of red ivory is delicious and can be eaten fresh or stored in containers, and is sold by hawkers in northern Limpopo. It is also a source of food for many birds and wild animals including baboons, vervet monkeys and bushbabies.

The wood is good for making strong and durable furniture, also wooden bows, walking sticks, small boxes, curios and fencing poles. In KwaZulu-Natal it was known as the ‘royal tree’ because only chiefs were allowed to carry knob-kerries made from Red ivory. The wood is also highly regarded in Mozambique.

Diospyros mespiliformis aka African ebony or Jackal-berry

Jackal-berry trees are found throughout Africa as well as in South Africa, where they are common in savannas or savanna woodlands like the Kruger National Park. It is one of the savanna giants that can live for over 200 years.

This tree has a dense, evergreen canopy and can grow up to 25 metres high, with a trunk circumference of five metres. It can often be found growing on termite mounds, and produces a fleshy oval, yellow-green fruit which is sought after by nyala, impala, warthog, baboons and hornbills.

The tree is widely distributed throughout the eastern part of the African continent, from Ethiopia to the south of Swaziland. It grows well in areas with plenty of water and little or no frost.

The tree is not threatened in South Africa, but because of its important role in the ecosystem and the food web, it is listed as a protected tree.

Many insects such as bees and wasps play a role in pollinating the flowers, while seeds are dispersed either through wash-off by rain or in the droppings of animals that feed on the fruits. Termites often build their nests around the tree and feed on the roots. The tree benefits from moisture and aeration as a result of termites burrowing in the soil beneath it. Snakes are often found around these trees as they prey on the rodents and birds that feed on the fruits.

Fallen fruit is eaten by kudu, impala, nyala and jackal, while the leaves are eaten by elephant, kudu and eland. The larvae of the emperor butterfly also feed on the leaves.

The fruit is popular with local people who eat it fresh or dried. The wood is tough and used to make spoons and canoes, while different parts of the tree are used for muti.

It is a good shade tree and makes an excellent screen or windbreak.

Schinziophyton rautanenii aka False balsa, Manketti tree or Mongongo nut

This tree can be found across Africa in southern Tanzania, southern DRC, Angola, Namibia, Botswana, Zambia, Malawi, Zimbabwe, Mozambique and in Limpopo province in South Africa.

It is a large spreading tree which usually grows to between 15 to 20 metres tall, with grey to pale golden-brown bark. Leaves are dark green above, pale grey below, turning bright yellow before falling.

The light grey-green fruit is covered in velvety hairs, while its hard seeds produce an edible oil.

It grows well on sandy soils in deciduous woodland, along rivers, on wooded hillsides, often on Kalahari sand and sometimes forming large stands.

Cuttings have been used in Angola for live fences and the tree has potential in desert encroachment prevention. A number of cases have been reported where fence posts made from freshly cut posts grew into large trees. The fibrous inner bark is used to make strings for nets and the seeds are used in board games.

The heartwood is straw-coloured and the grain is straight or wavy. The wood is very soft and light, but comparatively strong in relation to its weight, though not very durable. The wood is used for diverse purposes, including floats, canoes, notice boards, boxes, tools, musical instruments and carvings. It can be used as a substitute for balsa wood, hence the common name.

Umtiza listeriana aka Umtiza  

Umtiza is a localised tree, part of the legume family, that is found only in Southern Coastal Forest and Scarp Forest in the East London, Kentani and King William’s Town Districts of the Eastern Cape. This rare evergreen tree grows up to 12 metres in height and produces oblong leaves 20 to 60 mm long. Its dark green foliage make it ideal for small gardens or for use as a shade tree or screen. It is a slow grower, has rough dark brown bark and is covered in thorns.

Umtiza also produces fruit which matures into brown and woody pods.

Rapid human expansion in these areas threatens Umtiza which are becoming increasingly rare. It has been Red Listed as a Vulnerable Species. Umtiza trees are being restored in the Umtiza Nature Reserve near East London where it is reported to be doing well.

Umtiza has hard, oily wood and has been used to make propellor shafts for small boats. It is revered by Xhosa people who use it to ward off lightning and evil spirits.

For more info on these and other protected trees, visit

Below is a full list of the Protected Trees in South Africa.

Afrikaans (A), Northern Sotho (NS), Southern Sotho (S), Tswana (T), Venda (V), Xhosa (X), Zulu (Z)
Acacia eriolobaCamelthornKameeldoring(A), Mogohlo (NS)
Acacia haematoxylonGrey camel thornVaalkameeldoring (A) / Mokholo (T)
Adansonia digitataBaobabKremetart (A), Seboi (NS), Mowana (T)
Afzelia quanzensisPod mahoganyPeulmahonie (A), Mutokota (V), Inkehli (Z)
Balanites subsp. maughamiiTorchwoodGroendoring (A), Ugobandlovu (Z)
Barringtonia racemosaPowder-puff treePoeierkwasboom (A), Iboqo (Z)
Berchemia zeyheriRed IvoryRooihout (A), Munia-niane (V)
Boscia albitruncaShepherd’s treeWitgat (A), Mohlôpi (NS), Motlhôpi (T), Muvhombwe (V), Umgqomogqomo (X), Umvithi (Z)
Brachystegia spiciformisMsasaMsasa (A)
Breonadia salicinaMatumiMingerhout (A), Mohlomê (S), Mutulume (V), Umfomfo (Z)
Bruguiera gymnorrhizaBlack mangroveSwart-wortelboom (A), Isikhangati (X), Isihlobane (Z)
Cassipourea swaziensisSwazi onionwoodSwazi-uiehout (A)
Catha edulisBushman’s teaBoesmanstee (A), Mohlatse (NS), Igqwaka (X), Umhlwazi (Z)
Ceriops tagalIndian mangroveIndiese wortelboom (A), Isinkaha (Z)
Cleistanthus schlechteri var. schlechteriFalse tambotiVals-tambotie (A), Umzithi (Z)
Colubrina nicholsoniiPondo weeping thornPondo-treurdoring (A)
Combretum imberbeLeadwoodHardekool (A), Mohwelere-tšhipi (NS), Motswiri (T), Impondondlovu (Z)
Curtisia dentataAssegaiAssegaai (A), Umgxina (X), Umagunda (Z)
Diospyros mespiliformisAfrican ebony, jackal-berryJakkalsbessie (A), Musuma (V), Mgula (Tsonga)
Elaeodendron transvaalensisBushveld saffronBosveld-saffraan (A), Monomane (T), Ingwavuma (Z)
Erythrophysa transvaalensisBushveld red balloonBosveld-rooiklapperbos (A), Mofalatsane (T)
Euclea pseudebenusEbony guarriEbbehout-ghwarrie (A
Ficus trichopodaSwamp figMoerasvy (A), Umvubu (Z)
Leucadendron argenteumSilver treeSilwerboom (A)
Lumnitzera racemosa var. racemosaTonga mangroveTonga-wortelboom (A), Isikhaha-esibomvu (Z)
Lydenburgia abottiiPondo bushman’s teaPondo-boesmanstee (A)
Lydenburgia cassinoidesSekhukhuni bushman’s teaSekhukhuni-boesmanstee (A)
Mimusops caffraCoastal red milkwoodKusrooimelkhout (A), Umthunzi (X), Umkhakhayi (Z )
Newtonia hildebrandtii var. hildebrandtiiLebombo wattleLebombo-wattel (A), Umfomothi (Z)
Ocotea bullataStinkwoodStinkhout (A), Umhlungulu (X), Umnukane (Z)
Ozoroa namaquensisGariep resin treeGariep-harpuisboom (A)
Philenoptera violaceaApple-leafAppelblaar (A), Mphata (NS), Mohata (T), Isihomohomo (Z)
Pittosporum viridiflorumCheesewoodKasuur (A), Kgalagangwe (NS), Umkhwenkwe (X), Umfusamvu (Z)
Podocarpus elongatusBreede River yellowwoodBreederivier-geelhout (A)
Podocarpus falcatusOuteniqua yellowwoodOutniekwa-geelhout (A), Mogôbagôba (NS), Umkhoba (X), Umsonti (Z)
Podocarpus henkeliiHenkel’s yellowwoodHenkel-se-geelhout (A), Umsonti (X), Umsonti (Z)
Podocarpus latifoliusReal yellowwoodOpregte-geelhout (A), Mogôbagôba (NS), Umcheya (X), Umkhoba (Z)
Protea comptoniiSaddleback sugarbush
Protea curvataSerpentine sugarbushSerpentynsuikerbos (A)
Prunus africanaRed stinkwoodRooi-stinkhout (A), Umkhakhase (X), Umdumezulu (Z)
Pterocarpus angolensisWild teak KiaatKiaat (A), Morôtô (NS), Mokwa (T), Mutondo (V), Umvangazi (Z)
Rhizophora mucronataRed mangroveRooi-wortelboom (A), Isikhangathi (X), Umhlume (Z)
Schinziophyton rautaneniiManketti tree/Mongongo nut
Sclerocarya birrea subsp. caffraMarulaMaroela (A), Morula (NS), Morula (T), Umganu (Z)
Securidaca longependunculataViolet treeKrinkhout (A), Mmaba (T)
Sideroxylon inerme subsp. inermeWhite milkwoodWit-melkhout (A), Ximafana (X), Umakhwelafingqane (Z)
Tephrosia pondoensisPondo poison peaPondo-gifertjie (A)
Umtiza listerianaUmtiza
Warburgia salutarisPepper-bark treePeperbasboom (A), Molaka (NS), Mulanga (V), Isibaha (Z)
Widdringtonia cedarbergensisClanwilliam cedarClanwilliam-seder (A)
Widdringtonia schwarziiWillowmore cedarBaviaanskloof-seder (A)

Vergelegen wine estate plants trees for posterity

South Africa celebrated Arbor Week during the first week of September, and Vergelegen wine estate in Somerset West – a provincial heritage site renowned for its historic trees – marked the occasion in appropriate arboreal style.

A distinguished guest planted an oak tree sapling with a fascinating history, and garden staff revived the tradition of gathering seeds from an ancient yellowwood and distributing these to visitors.

Royal connections
It is a Vergelegen custom to invite visiting dignitaries to plant a commemorative oak, and the estate has a fine collection planted by members of Britain’s royal family and other visitors. The oak tree planting on this occasion was undertaken by Mary Carlisle, renowned for her work with under-privileged communities in KwaZulu-Natal, on a visit to the estate on 2 September.

This oak sapling has a fascinating lineage, says Vergelegen Gardens Manager Richard Arm. It originates from an acorn from a famous tree at Vergelegen known as the Royal Oak. That Royal Oak, in turn, grew from an acorn planted decades ago when Vergelegen was owned by Sir Lionel and Lady Florence Phillips, from 1917-1940.

“Lord and Lady Phillips were friends of the Duchess of Marlborough, who had given Sir Lionel this acorn. It came from one of the last of King Alfred's mediaeval oaks at Blenheim Palace in Oxfordshire, England. This acorn survived the sea trip from England to the Cape in the 1920s and duly grew into the giant oak known as the Royal Oak.”

Since then, acorns from the Royal Oak have been taken back to England for planting in Blenheim Palace and Windsor Great Park.

“We planted the sapling close to the existing Royal Oak so that in a couple of hundred years, oaks can still be enjoyed as part of the heritage of the Cape,” says Arm.

Seed distribution
Vergelegen is also home to a vast yellowwood (Podocarpaceae, a protected national tree) estimated to be 150-400 years old.

This venerable old specimen is the source of hundreds of seeds which the horticultural team traditionally gather every year. They skipped this custom in 2020 due to the Covid-19 lockdown, but revived it this year.

“The seed handout at the gate was extremely well received by all our guests,” says Arm, who adds that the seed collection and germination are made easier by resident fruit bats.

The bats not only drop the seeds in certain areas of the garden, so that the team know where to find them, but they also nibble at the skin and fleshy part of the fruit to expose the seed, which helps germination.

Tree viewing
Vergelegen visitors can walk the Yellowwood Trail to the site of this magnificent old yellowwood. Other outstanding trees include five enormous camphor trees (Cinnamomum camphora) outside the homestead, which were declared national monuments in 1942. These are the oldest introduced cultivated trees in southern Africa, and were also the favourite trees of President Nelson Mandela on his visits to Vergelegen.

The collection also includes a hollow old English oak, believed to be the oldest living oak in Africa, and an oak arboretum. The arboretum is home to about 15 varieties of oak and helps to increase awareness of the history of oaks in the Cape, and the conservation and propagation of these trees.

Members of the public are welcome to visit he estate which is open Monday-Sunday 09h00-17h00.

For more info visit and social media.

Tree experts rally to save iconic Cape trees

Tree health experts from around the country are collaborating in efforts to save four iconic native tree species found in the Cape that are under threat: the Silver trees of Table Mountain, southern Cape tree ferns, milkwoods and the Clanwilliam cedar.

Silver trees
Kirstenbosch National Botanical Garden, in collaboration with the Botanical Society of South Africa, Table Mountain National Park (TMNP), FABI (Forestry and Agricultural Biotechnology Institute) and the South African National Biodiversity Institute (SANBI), has launched an innovative project to save the endangered Silver tree (Leucodendron argenteum) which only occurs naturally in a tiny area of the Cape Peninsula.

The Silver tree, also known as the Silver Leaf Tree, Witteboom, or Silwerboom, is a protected evergreen tree which is part of the Protea family. This enormous silver Protea is naturally confined to a tiny area in and around the city of Cape Town – with its main population growing on the slopes of Table Mountain, notably the Lion's Head area, above Rhodes Memorial and the mountain slopes above Kirstenbosch National Botanical Garden.

Historically, the Silver tree was widespread on Table Mountain, covering much of its slopes in shimmering silver forests. However, early demand for timber led to much of these forests being felled and now the Silver tree is a rare and threatened species - in danger of becoming extinct in the wild in the next 50 years.

Unfortunately the Silver tree is susceptible to infection from the fungus Phytophthora cinnamomi, a soil borne pathogen that causes root and collar rot. Phytophthora feeds on living plant roots and stems, reducing the plants’ ability to transport water and nutrients – often leading to the death of the host.

This introduced pathogen is present in wild Silver trees as well as in the population found in Kirstenbosch National Botanical Garden, where it is causing the death of many of these iconic trees.

In a bid to save the Silver trees, Kirstenbosch staff, in collaboration with FABI, have launched an innovative treatment trial.

“We are testing the application of phosphite, a biodegradable fungicide which can protect plants against Phytophthora die-back. Phosphite will not eradicate Phytophthora from the soil, but it can protect plants from infection, and can help them recover if they are already infected,” explained Dr Trudy Paap of FABI.

“We have sprayed some of the Silver tree seedlings and injected bigger trees with phosphite. We have also left other plants untreated, as controls, and are monitoring the survival rates of the treated and non-treated trees.”

Phosphite is used in South African agriculture and horticulture settings to guard against Phytophthora root and crown rot of several important commercial crops. However, it has never been applied to indigenous South African flora before.

When the FABI research team re-visited Kirstenbosch in May they found good evidence that the spray applications that were done in 2020 have been effective in reducing the impact of the disease on young plants.

A number of bigger silver trees were also treated with phosphite during this visit and the results will be evaluated later this year.

Milkwood trees
Another natural tree on the radar of the FABI team is the milkwood tree (Sideroxylon inerme) that has been dying in the Hermanus area. The problem was reported to the FABI team by well-known tree surgeon, Leon Visser.

A tree health survey in May enabled the team, including Prof. Mike Wingfield, Prof. Brenda Wingfield, Prof. Francois Roets (Stellenbosch University) and Dr Trudy Paap, together with ecologist Dr Casper Crous to join Leon to inspect the trees. These trees had symptoms of various stages of decline with many having already died.

Roots and above ground parts of the trees were inspected and samples were collected for further study. Although opportunistic pathogens may be involved in the problem, the group was generally of the opinion that an environmental factor is likely to be the initial cause. Mike Wingfield says the team suspects water issues, which could have resulted from the opening up of the land for housing construction. He says that the trees that are dying appear to be close to the houses, and there is no obvious indication of a pathogen problem.

Tree ferns
Iconic tree ferns Alsophila (Cyathea) dregii have been observed dying in southern Cape forests for some years. These plants appear to die very rapidly and populations of these tree ferns - such as those found in the Knysna forests - have collapsed dramatically.

A recent inspection of the trees by the research team noted that tree ferns that were only slightly affected during a previous visit have now died, with some areas having almost no living plants left. The team took samples of these trees and it is hoped that laboratory research will lead to a better understanding of this dramatic decline.

Clanwilliam cedar
FABI initiated a research project in 2020 focused on the fungi associated with bark beetles infesting the Clanwilliam Cedar Widdringtonia (cedarbergensis) wallichii. This work stemmed from earlier research during the 1980s, to consider the possible role of insects and fungal pathogens in the demise of these iconic trees.

The project is being led by Prof. Mike Wingfield, Prof. Brenda Wingfield and Prof. Francois Roets (Stellenbosch University) and supported by MSc student Handré Basson.

During their recent Cape visit the research team undertook a survey of beetles infesting Widdringtonia nodiflora, a species that is more widespread than W. wallichii. Beetles infesting these trees were found and collected for further laboratory work. This will make possible a comparison of the beetles and their fungal associates on the two tree species and provide further insight into their role in tree decline.

The Clanwilliam cedar, which is endemic to the Cederberg and is protected within the Cederberg wilderness area, is considered critically endangered. This species, which once grew in abundance in the Cederberg, was heavily logged for timber by the early European settlers who arrived there in the late 18th century, as there were few other trees growing naturally in these mountains.

In 1879 alone more than 7 000 trees were cut down for use as telephone poles. This overexploitation caused a significant reduction in the Clanwilliam cedar, and the species never properly recovered.

Researchers have suggested that the ongoing decline over the past century could be due to a harmful fire regime. Monitoring of permanent plots set up 29 to 35 years ago distributed across this species range indicates that a 94% decline of mature individuals has taken place in less than one generation (66 - 200 years).

Champion tree
Fabi tree health researchers were recently alerted to a concerning die-back affecting introduced Araucaria trees in Stellenbosch. Dr Trudy Paap joined the well-known arborist and tree climber Leon Visser, who assisted her in climbing some of these trees to sample their dying tops. This included a 200 year-old ‘Champion Tree’ Araucaria heterophylla (Norfolk Island pine). At 45m, this is the tallest tree in town.

The trees had symptoms of a top-down die-back, and with Leon’s help, Trudy was able to sample the trunks at the disease interface. It is suspected that the extreme drought that occurred from 2015-2017 played a significant role in the die-back, and that opportunistic pathogens may also be involved. Being able to collect samples right at the point of interest in the canopy, however, presented an opportunity to confirm the identity of biotic agents. It is hoped that the knowledge gained from this unique sampling effort will help guide a strategy to limit the decline and restore tree vigour.

Related article: Indigenous trees of Southern Africa (Part 3) – Cape Ash

Indigenous trees of Southern Africa (Part 3) – Cape Ash

By Gareth Coombs

Cape Ash (Ekebergia capensis) is a large semi-deciduous tree that naturally occurs along the entire coast from Cape Town and surrounds, eastward to Mozambique, and into areas along the north and South East of Zimbabwe. It has a disjunct distribution, and is also found in Northern Botswana. Owing to its lush canopy and attractive branching pattern it makes an excellent garden and street tree. Large trees can reach up to 30 metres in height but are usually smaller, ranging from 7-15 metres. Mature trees can have different branching patterns but the branching is usually upright and spreading widening from the base to the top of the canopy. The growth form can be different depending on its environment. It can also spread laterally and form a rounded, lush green canopy that makes and excellent shade tree for gardens and public spaces.

No discussion on the Cape Ash or Cape plum is complete without that of distinguishing between the appearance of the two. Due to the similarities of Cape Ash and Wild Plum, there has always been some debate on how to readily distinguish these. The easiest distinguishing feature are the fruits which will allow you to instantly distinguish the round, berry shaped fruits of the Cape Ash from the much larger oblong, bright red coloured plums of the Wild plum. When these are not fruiting, the difference can be told apart by the leaves that are distinctively more sickle shaped in the Cape plum and straighter in the Cape Ash.

Collecting fruits and seeds

This species produces distinctive large berries, each usually containing 1- 4, kidney shaped seeds. The fruit color varies from a lightly streaked red and cream colour to a darker uniform crimson red. Green fruits are borne for 2-3 months on the tree before ripening when they are often distinctively seen on the tree and can form a dense litter on the ground where they drop. This is however seldom a nuisance to traffic or pedestrians. Fruiting trees are commonly found throughout cities, towns or gardens and the fruits can either be picked directly from the tree or picked up from the ground. Once fruits have been collected they can be stored for several days with the pulp still present, however, the pulp invariably begins to decay and attracts small fruit flies. It is therefore advisable to first remove the pulp from the seeds and store seeds after the fruit pulp has been cleaned off. Seeds can be washed with a diluted solution of household bleach (sodium hypochlorite) which inhibits fungal decay during storage. Despite the soft fleshed fruits, the seeds can be stored for at least one season, and will survive longer than this in optimal conditions.

Planting seeds and propagation

Seeds should be planted from late august to March and germinate well in mixture of 1-2:1 compost: field soil. Seeds can be sown in bags or seed trays at a depth of 3 cm. Once planted the soil must be kept moist, in a shaded area. Personal Nursery data indicates median germination period of around 47 days. Newly germinated seedlings bare two cotyledons that remain close to the soil and as the newly developing stem grows from these. This is different Cape plum where the cotyledons are kept closer to the leaf petals as the seedling stem develops. As the seedlings develop, the cotyledons shrink and become wrinkled as seedling ages. Seeds can be stored dry for some time, but there is some reduction in their viability. When the growth tip is removed, new meristems sprout from the base of the cotyledons, same in some other species.

Germinated seedling can be pricked out from planting trays very carefully and transplanted at any time from 3-5 days after germinating, however very young seedlings can be prone to damping off fungi and allowing seedlings to reach larger sizes before transplanting is advisable.

Seedling care and planting out

Seedlings can be grown for several months within the original planting container and do not compete aggressively. Once seedlings reach about 25cm they are ready for transplanting. Larger seedlings will usually transplant better and are less susceptible to fungal infection. Seedlings are not very drought tolerant and need to be watered regularly, as water stress is often followed by the development of wilting diseases in this (and other) tree species. Plants should be kept in shaded or at least partial shade for the first year until they are large enough to harden off and plant in full sun. This is a relatively fast growing species and can reach over 1m in 3 years when grown from seed. Growth rate of seedlings is variable and up to appr. 30 cm per year for the first two years, but this could be faster under optimal irrigation and fertilizing schedules.

Natural history notes
Cape ash is a valuable fruit tree that provides both habitat and a food source for birds and mammals. including baboon, vervet monkey, bushbuck, nyala, red winged starlings, Knysna turaco, black collared barbets and crowned hornbills.

Selected references and further reading
Dlamini, M.D. 2004. Ekebergia capensis Sparmm. SANBI. Available online at:
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of southern Africa, 3rd Ed. Struik, Cape Town.

*Related article: Indigenous Trees of Southern Africa (Part Two) – Cape Plum