The ecological and cultural aspects of this tree, its lovely aesthetic
qualities and its relatively widespread distribution in southern
Africa, make this species perhaps the best known Canthium
in the region.
to the wide range of habitats in which it occurs and the diverse
environmental conditions associated with this, the species exhibits
much variability in terms of growth form and size. Under forest
conditions, where strong competition for light necessitates upward-reaching
growth, heights of up to 14 m may be attained. In contrast, those
in more exposed conditions grow notably shorter in height, commonly
between 3 m and 7 m, and assume a more spreading habit and rounded
crown. Trees may be single or multistemmed, with main stems achieving
diameters of up to 360 mm.
young, the stems are smooth and pale grey, becoming rougher and
darker with age, and forest specimens often exhibit impressive twisted
and fluted stems with rough, flaking bark. The smooth, light-coloured
stems are a very attractive feature of the species, allowing the
tree to stand out visually against its surrounds.
The branches are borne in opposite pairs with each pair at right
angles to the next, this being a very distinctive character of the
species and indeed other members of the genus also.Branches, and
sucker shoots in particular, are often armed with strong, stout
spines up to 70 or 80 mm long, produced just above the nodes in
opposite pairs. Leafy spine-like branches are occasionally encountered.
leaves are a lovely ornamental feature and are light green, glossy
and hairless with a soft, leathery texture. They are simple and
opposite, are elliptic in shape and range from 25-100 x 10-45 mm.
The leaf margins, which are entire (untoothed) and often undulate,
are slightly rolled under and domatia (small pockets), often containing
hairs, are present in the axils of the veins on the leaf undersurface.
The petioles (leaf stalks) are up to 15 mm long, between which stipules
up to 4 mm in length are produced, these interpetiolar stipules
being characteristic of the family as a whole.
to green-yellow flowers are produced from August to February. They
are small in size and usually in dense axillary clusters up to 30
The 2-lobed, 2-seeded, oval-shaped fruits are produced from October
to April. They are glossy green when young but, in ripening, become
dark brown and wrinkled and may remain on the tree for many months.
far as canthiums are concerned, this species is not likely to be
confused with others in the genus with the exception perhaps of
C. suberosum which it superficially resembles. The latter
however lacks spines or spine-like branchlets and young branches
are somewhat powdery becoming noticeably corky on older stems, unlike
in C. inerme. C. suberosum is also less extensive
in its distribution.
Canthium inerme is a relatively common species with a wide
distribution range in southern Africa. Palmer & Pitman (1972)
note this range as extending from the Cape Peninsula in the Western
Cape, into Eastern Cape, through KwaZulu-Natal, Swaziland, Mpumalanga,
and Limpopo, Mozambique and Zimbabwe. It is found in a variety of
habitats from coastal and montane forest, dune forest and forest
margins, to bushveld and rocky grasslands. The altitudinal range
is quite impressive, stretching from coastal areas to around 1 700
m above sea level. According to Von Breitenbach (1965), the species
is frequent in coastal scrub and drier forest types, becoming less
so in the medium-moist forests and near absent from the moist and
wet forests. It is not a species of very arid conditions.
Derivation of name and historical aspects
The plant family to which the Canthium genus belongs is the
renowned and much-admired gardenia family, the Rubiaceae. The Rubiaceae
holds the distinction of being the largest family of trees in southern
Africa comprising roughly 160 indigenous to the region. It is among
the world's largest families of flowering plants with approximately
637 genera and some 10 700 species, most strongly represented in
the tropics but cosmopolitan on the whole (Allaby 1998).
Most members of the Rubiaceae, which include herbs, shrubs, trees
and climbers, share some common features which quickly indicate
their belonging to the family, namely leaves which are opposite
and entire with interpetiolar stipules. Much taxonomic work however
still remains to be done on the family. It is probably most famous,
not only for its numerous horticulturally valuable members, which
include the all-popular genera Gardenia, Ixora, Pavetta,
Pentas and Rothmannia, but for quinine, from the South
American Cinchona species, and coffee, mainly Coffea arabica
and C. canephora. The extent of the latter's fame is apparent
when one considers that it is the world's second largest revenue
generator for a natural product after petroleum (Van Wyk & Van
The Canthium genus is comprised of trees and shrubs totalling
roughly 50 species, occurring in Africa, the Indian Ocean islands
and Asia. Of these, around 15 species in southern Africa are listed
as trees, these being concentrated mainly in the eastern parts of
generic name Canthium is derived from the word canti,
the Malabar (Indian) name for a member of this genus (Palmer &
Pitman 1972). The specific epithet inerme is intriguing as
it literally means unarmed or without spines. This is not always
the case, however, as spines are clearly evident on some specimens.
As for the vernacular names, the English name turkey-berry is believed
to refer to the fact that turkeys take a particular liking to the
fruit. The very descriptive bokdrol, Afrikaans for antelope
droppings, in reference to the resemblance of these to the fallen
fruit, is also fitting.
The common turkey-berry clearly is a species with much ecological
value and interest. A large proportion of the trees are known to
bear fruit annually, although some not so regularly. Pollination
is effected by bees in search of pollen and nectar, and self-pollination
is also seen to take place (Von Breitenbach 1965). In commenting
on other ecological aspects of this species, Von Breitenbach (1965)
states that 'Fruits mature and fall after 3-4 months, and are eaten
and dispersed by various birds and wild pigs. The larger proportion
of the fruit crop falls prematurely. Many seeds are destroyed by
doves and wild pigs, and by Dipterous larvae'.
Birds indeed play an important role in seed dispersal, carrying
seed from the plant to often distant and scattered localities. Success
in germination at these new localities is determined largely by
the environmental conditions present as well as seed viability.
In addition, the fruits are eaten by people and the tree serves
as one of the host plants of the Natal Barred Blue butterfly (Spindasis
natalensis). With regard to disease, species of Capnodium
attack and prove fatal to some seedlings, while a species of leaf
mould (Meliola woodiana) is known to attack more mature plants
(Von Breitenbach 1965).
Uses and cultural aspects
Canthium inerme, like so many tree species in southern Africa,
is utilized for medicinal purposes, the leaves being used in the
treatment of stomach ailments (Coates Palgrave 2002) As mentioned
previously, the fruits are eaten by people. The tree has been much
used as shelter for stock, while the wood, which is hard, heavy
and tough, is handsome and has been used in wagon-making and for
furniture (Palmer & Pitman 1972). The species, with its horticultural
potential becoming increasingly recognized, is now commonly encountered
in the South African nursery trade.
Growing Canthium inerme
inerme is relatively easy in terms of propagation and is best
grown from seed. Seeds should be collected when ripe and cleaning
of these is recommended prior to sowing. Sowing can be done in trays
or seed beds in a rich, well-drained medium, with equal parts of
sand and compost.Place in a warm, brightly-lit area and keep moist
but not wet. Germination times may vary, depending on the time of
year, from under a month to up to 2-3 months and growth is rapid
once germinated. Following germination, allow the seedlings at least
2-3 weeks of growth before transplanting into bags or other suitable
containers for further growing.
It is a beautiful and charming tree and greatly recommended for
the garden setting where its low-growing and compact habit makes
it ideal where space is slightly limited. Its evergreen nature ensures
that its attractive foliage is present throughout the year and its
presence is bound to attract numerous fruit-eating and insectivorous
birds. The thorns, though stout and strong and worthy of respect,
are generally not as menacing as some gardeners are led to believe
and in fact give the tree a lovely visual quality. Plant in a large
hole with plenty of compost and ensure watering is carried out until
established. It is fairly hardy and because of its ability to tolerate
a range of conditions, can be used in a variety of garden habitats
to great effect.
References and further reading
- Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of
southern Africa, edn 3. Struik, Cape Town.
- Lotter, M., McCleland, W. & Schmidt, E. 2002. Trees and
shrubs of Mpumalanga and Kruger National Park. Jacana, Johannesburg.
- Palmer, E. 1977. A field guide to the trees of southern Africa.
- Palmer, E. & Pitman, N. 1972. Trees of southern Africa,
3 vols. Balkema, Cape Town.
- Pooley, E. 1993. The complete field guide to trees of Natal,
Zululand and Transkei. Natal Flora Publications Trust, Durban.
- Tilney, P. 2003. Canthium, Keetia and Psydrax (Rubiaceae) in
South Africa, Part 2 : how to recognize the South African species
of Canthium. Plantlife 28: 19-25.
- Van Wyk, B. & Van Wyk, P. 1997. Field guide to trees
of southern Africa. Struik, Cape Town.
- Von Breitenbach, F. 1965. The indigenous trees of southern
Africa. Department of Forestry, Pretoria.
Kirstenbosch National Botanical Garden