Iconic trees of Kloof

Text Richard Boon Photographs Richard Boon, Sharon Louw, Hugh Chittenden

About Richard Boon

My interest in nature started when I was about 18 and began with the common garden birds. A friend suggested I visit Pigeon Valley Nature Reserve to see more species and I fell in love with the place (I estimate I have visited over 1 000 times). On my first visit, I was trailed by Geoff Nichols who managed the reserve at the time and watched over it like a hawk. When he realised I was there for legitimate reasons, we got talking. It didn’t take me long to realise that I had just met the best naturalist in Durban. This was the start of a new journey for me as my interest in birds diversified to an interest in nature and with Geoff’s help I started learning plants.

In the final year of my degree, I did a project at Twinstreams near Mtunzini and met Ian Garland on a day that we separately found a Pied Wheatear on his farm. I remember us poring over books in Ian’s study and we then called renowned ornithologist Ian Sinclair to tell him that we thought we had found a new species of bird for South Africa. We were thrilled when Ian Sinclair confirmed our sighting! During this period Ian Garland introduced me to his good friend Hamish Campbell who became my next mentor. Hamish was the most exceptional person I have met. He had a great love for Vernon Crookes Nature Reserve, birds and people. Travelling with Hamish, we would visit Vernon Crookes nearly every Sunday to arrive before dawn to watch stars and listen to the dawn chorus further nurturing my interest in nature.

With my interest fully stoked, I decided to do my MSc. on small urban nature reserves and used Pigeon Valley and Natal Robins (or Red-capped Robin-chats, a name I can’t get used to because ours is not Red-capped) and other birds to investigate various island biogeography questions. My supervisor was Professor J.C. Poynton, a top African amphibian taxonomist who was internationally renowned for his interest and knowledge about the philosophy of science. Whilst still completing my studies, Prof Poynton emigrated to the United Kingdom and Debra Roberts, a previous student of Prof. Poynton, kindly agreed to take over as my supervisor and was later to have a major influence on my career.

In the 1990’s I joined WESSA as a Conservation Biologist where Keith Cooper was my boss. Keith had an excellent knowledge of trees having published on Natal and Transkei forests and this further developed my interest in trees so much so that in 2002 whilst working for eThekwini Municipality I was asked by the Flora and Fauna Publications Trust to join a project team to revise The Trees of Natal, Zululand and the Transkei by Elsa Pooley, which was first published in 1993.

It was a fantastic opportunity, which I naturally accepted. In time, other team members found they had less time to devote to the project than they originally thought and I ended up being responsible for the revision, a job which was only completed in 2010 when the field guide was finally published.

I am always keen to share my knowledge and promote information on trees so gladly accepted Kloof Conservancy’s request to write a two part article on the trees of Kloof. In this first part I cover some of the more frequently seen and recognised trees and in the next edition I will cover some of the rare trees of Kloof.

EUPHORBIACEAE – Euphorbia family

Macaranga capensis River Macaranga

The River Macaranga is a deciduous, fast-growing, medium to tall tree reaching a respectable 25 m in height. Macaranga is an Old World genus of about 300 species, with only two species occurring in southern Africa. The River Macaranga mostly grows in wet areas, often in forest and forest margins, from the northern Eastern Cape to Ethiopia and Sudan. The trunk is straight and usually buttressed. Buttress roots are a common feature of our scarp forest trees as they help prevent toppling, which is useful where trees grow on shallow soils and experience strong winds. The leaves are large, poplar-like and often egg-shaped and the base is frequently more or less square. The apex has a short, but distinct drip tip. Drip tips may help to remove water from leaf surfaces and prevent the build of fungi and bacteria. The leaves have three distinct main veins and the stalk is long and often tinged pink. Unusually for local trees, the stalk is attached to the lower s urface of the leaf near the margin rather than at the margin (peltate). The tiny flowers are presented in long sprays and trees are either male or female. The fruit is a capsule and contains one seed with a soft, pinkish aril. River Macarangas can be used to secure stream banks. The wood is useful for construction and furniture and the bark is much sought after for medicinal uses.

CELTIDACEAE – White-stinkwood family

Celtis africana White-stinkwood

White-stinkwoods are fast growing, deciduous trees, which under certain conditions reach sizeable proportions. The hyphenated common name is an attempt to distinguish the three South African Celtis species or White-stinkwoods from the true Stinkwood (Ocotea bullata), an unrelated tree. Celtis species were previously included in the Elm family Ulmaceae, were moved to the Celtidaceae and have more recently been included in an enlarged Cannabaceae family. Take your pick! The combination of buttressed stem, pale bark and bare branches in winter is very attractive. The inconspicuous flowers open in early spring and appear with the fresh-green growth. This is an easy tree to identify. Celtis africana leaves have asymmetrical bases and there are three main veins. The leaf margin is serrated in the upper two-thirds. The yellow fruit ripens in late summer to autumn and is relished by birds and monkeys. They make great garden and landscape trees where space allows. If you grow a White-stinkwood, make sure your plant is from a local source. Upcountry ecotypes differ and have hairy leaves. You also need to watch out for the similar alien species, referred to elsewhere in the world as hackberries or nettle trees that have naturalised, especially on the Highveld. In some summers White-stinkwoods and the Pigeonwood (Trema orientalis) can be completely defoliated by the slimy grub of a beetle called Galerucella trilobata. The beetles cause no serious harm to the trees and the infestation soon passes, sometimes assisted by cuckoos.

MELIACEAE – Mahogany family

Trichilia dregeana Forest Natal-mahogany

Forest Natal-mahogany, photo by Richard Boon

Forest Natal-mahogany in Glenwood, photo by Richard Boon

This large, evergreen tree easily reaches 20 m and more in its coastal and scarp forest habitats. The crown is dark and rounded and casts good shade, which makes it an excellent street tree for Durban’s long, hot summers. In the central suburbs it’s cover makes it a favourite for roosting Common Mynas, Ring-necked Parakeets and Hadedas. A well-known specimen in the Kloof Gorge has provided a home for breeding Crowned Eagles for many years. The dark green, compound leaves have 3–5 pairs of leaflets plus a terminal one. The cream-coloured, scented flowers appear in spring to summer, male and female on separate trees. Flowering is followed by abundant, large, round fruits which split into three when ripe releasing the big black seeds partially covered by a fleshy, scarlet aril. Arils are fleshy appendages found on some seeds. The seeds are eaten by birds, bats and people. The leaves are the food of White-barred Charaxes caterpillars. Forest Natal-mahoganys make hardy indoor plants.

APOCYNACEAE – Amatungulu or Oleander family

Rauvolfia caffra Quinine-tree

Quinine tree in Oribi Gorge, photo by Richard Boon

This is another big tree, which is usually deciduous in winter. It prefers moist habitats, but given its large, soft leaves, it is remarkably tough and does well as a landscape tree in drier places, even when exposed to strong wind. Don’t plant Quinine-trees where the roots will cause problems. The fresh-green new growth is very attractive as is the chunky, corky, pale yellow-brown bark. The large leaves are unusual in being arranged in whorls of up to six at branchlet ends. The veins are pale and evenly spaced. Break off a leaf and a copious, milky sap will ooze from the wound. The small, white flowers are inconspicuous and presented in large clusters in spring. They are attractive to various insects. The fruits are often paired, ripen black and are eaten by birds. The bark was reputed to be effective against malaria parasites, but failed clinical testing. The tree is rich in alkaloids and is widely used in traditional medicine in Africa. Scientific tests have shown that under certain circumstances the compounds found in our Quinine-tree show anti-oxidant properties comparable with that of commercial drugs. An Asian relative R. serpentina Indian Snake-root contains many alkaloids and has been used with varying success to treat venomous stings and bites, high blood pressure and mental diseases.

BURSERACEAE – Corkwood family

Commiphora harveyi Copper-stem Corkwood

Copper-stem Corkwood, photo by Richard Boon

Copper-stem Corkwood, photo by Sharon Louw

Corkwoods are part of a large genus whose members are usually easily recognised as related by their peeling or flaking bark, milky or cloudy sap and aromatic resin – frankincense and myrrh come from the latex of members of the family. They are generally found in hot, dry savanna and thicket. Durban lies south of the range of most Corkwoods, but three species are found in our dry forest and valley bushveld. The stand out feature of the Copper-stem Corkwood is the bark which peels or flakes in coppery-bronze strips or discs. They are deciduous, medium-sized trees and are popular landscape and bonsai subjects. As they transplant easily, gardeners should take care not to buy ‘instant’ trees, which may have been plundered from nearby bush. Commiphora plants are dioecious, which means the inconspicuous male and female flowers are found on separate trees. The fruit is about olive-sized and splits into two to reveal a stone, which is partially enveloped in red, fleshy fingers. They are attractive to birds and monkeys. Photo of Corkwood fruit: Sharon Louw

PHYLLANTHACEAE – Potato-bush family

Anitdesma venosum Tassel-berry

Tassel-berry tree, photo by Richard Boon

Tassel-berrys are common, small trees that grow on forest margins and in wooded grassland. Although part of a large genus, only four tassel-berry species are found in southern Africa. They were formerly included in a large family including the succulent euphorbias, but taxonomists now understand the heterogeneous Euphorbiaceae to be an artificial group and the family has been split to better match molecular evidence. A. venosum has a wide distribution in Africa and is a small tree with a round to spreading crown. The individual flowers are small and lack petals, but the inflorescences are eye-catching, pendent, tassel-like catkins. The flowers have a somewhat unpleasant scent, especially on warm, still summer evenings, and are very popular with insects, which themselves attract insectivorous birds. Male and female flowers occur on separate trees and the female flowers develop into attractive tassels bearing small, sweet fruits. Ripening is staggered and each tassel simultaneously bears cream, pink, red and deep purple fruits, which are enjoyed by birds, monkeys and people. They are attractive and productive garden trees.

ARALIACEAE – Cabbage-tree family

Cussonia sphaerocephala Forest Cabbage-tree

The Forest Cabbage-tree is an emergent forest tree with large, dark green, complex compound leaves clustered in distinct round heads, hence the Latin name sphaerocephala or round head. C. sphaerocephala is a regional endemic confined mostly to KwaZulu-Natal where it grows at low to medium altitudes. Large specimens have minor buttressing at the base and corky stems. The flowers are arranged at the end of the long stems in dense spikes clustered in umbels, which are in turn arranged in a larger umbel, thus forming a twice-compound inflorescence. The inflorescences take two seasons to develop. The greenish-yellow flowers are very attractive to insects, especially flies. The fleshy, cone-shaped, purple fruits are eaten by birds and monkeys. Cabbage-trees make excellent landscape feature plants, but they shouldn’t be grown where their roots can damage built structures. Some of the other local species are slighter and better suited to small gardens.

Photo of Knysna Turaco: Hugh Chittenden

FABACEAE – Pea family

Erythrina lysistemon Coral-tree

Coral tree in Oribi Gorge, photo by Richard Boon.

Coral tree in Shongweni, photo by Richard Boon.

The Coral-tree is a small to medium-sized tree and in KwaZulu-Natal grows in low altitude bushveld, coastal bush and wooded grassland. The leaves are compound, each with three leaflets. Scattered, hooked prickles are found on the trunk and young stems. The soft wood is often used by woodpeckers and barbets to make nesting holes. E. lysistemon is winter deciduous and the bare trees covered in bright red flowers add interest to the otherwise muted colours of our winter landscapes. Curiously Coral-trees grow fairly sparsely in natural areas relative to their widespread and frequent use in cultivation. The similar Coast Coral-tree is also frequently cultivated and has more orange flowers with the standard petal (the largest one) short and broad and exposes the stamens versus the narrow and red standard of E. lysistemon, which encloses the stamens. The Coast Coral-tree doesn’t occur naturally at Durban. The flowers of all Coral-trees attract nectivorous birds, and monkeys which eat the buds. The sickle-shaped pods contain red and black seeds, which are used as lucky charms. The seeds are poisonous if eaten in quantity. Coral-trees can be grown easily from seed or truncheons and are planted on the graves of chiefs and as living fences around homesteads.

PROTEACEAE – Protea family

Protea roupelliae Silver Protea

Silver Protea in Lotheni, photo by Richard Boon.

This small tree is the largest of the four summer rainfall proteas found in Durban, growing to around 8 m tall. It grows over a wide range of altitudes and locally it is found from about Pinetown to near the tree line in the Drakensberg Mountains. The bark is thick, grey to black and fissured. Mature plants can withstand most fires, but too frequent or hot fires kill the seedlings. The leaves are clustered in rosettes and are silvery or dark bluish-green and the silvery colour and hairs distinguish it from the paler blue-green, hairless leaves of P caffra. There is a dense stand of P. caffra just south of the Kloof Falls Road view site, while a grove of P. roupelliae occurs not far north of the view site. Protea flowers are clustered in large flowerheads surrounded by showy bracts, the innermost of which in P. roupelliae are spoon-shaped and fringed with hairs. P. roupelliae has a goblet-shaped flowerhead. Protea inflorescences are visited by sunbirds, beetles and bees. The seeds are small nuts.

SCROPHULARIACEAE – Snapdragon family

Halleria lucida Tree-fuchsia or Halleria

Tree-fuchsia in Krantzkloof Nature Reserve. Photo by Richard Boon.

The Tree-fuchsia or simply Halleria is usually a small, multi-stemmed tree found from South Africa to Yemen in forest margins, bushclumps near forest and as stunted plants on exposed rock outcrops. In temperate forests this species can grow much taller. The foliage droops giving the tree an attractive willowy appearance. The leaves are opposite, have more or less square bases and margins are serrate or scalloped. The tubular, orange, hanging flowers are produced in profusion on old wood (this is called cauliflory) and in smaller clusters on new growth. They appear in winter and are highly attractive to sunbirds and bees. The round fruit is crowned by a wispy thread and ripens to blackish-purple, although ripe fruit is not often seen because birds love them. The combination of nectar-rich abundant flowers and palatable fruit and the generally small size of this tree make this one of the best garden plants. It is easily grown from seed and does better in the more temperate Highway area than on the coast.

About the Author

Richard Boon is well known not only for his outstanding book Trees of Eastern South Africa – A Complete Guide but also for his environmental work at WESSA in the 90’s and since 2000 as part of the Environmental Planning and Climate Protection Department at eThekwini where he heads up the Biodiversity Planning Branch. Richard is a practical botanist with over 20 years’ field experience. He also enjoys photographing plants and other natural subjects.