Yes, those white spots in the forest are too big to be bird splats. They are actually flowering trees of Combretum woodii, and what you see from across the valley is a whole tree full of the white leaves that surround the flowers.
Description: Tree up to 6 (rarely 10) m tall; young stems do not give as much the impression of trying to climb as in C. kraussii. Bark grey, smooth at first, later peeling in large sheets or splitting into small rectangular blocks. Leaves alternate to opposite, without stipules, apple green, younger leaves around flower spikes white, elliptical to obovate, 65-150 x 25-75 mm, dull, hairless, margins wavy and not rolled under, blade often curved upwards. Flowers typical of the genus, in short spikes surrounded by white leaves (October to November in KwaZulu-Natal ). Fruits 4-winged, relatively narrowly ellipsoidal, the wings also quite narrow, the whole yellowish green with a pink (not dark red) tinge. Trees grow slowly and the rarity of this species is debatable, as plants are inconspicuous in the forest except when in flower, and more than a few almost inaccessible populations are not yet recorded.
Distribution and Habitat: This bushwillow occurs sporadically in KwaZulu-Natal (KZN), Swaziland and Mpumalanga. In KZN its western limit is near Underberg (Carr 1988), but it is more characteristically seen in the Umgeni River Valley near Inanda Dam (below the Durban suburbs of Waterfall and Crestholme), in the Tugela Valley below Kranskop, and sporadically northwards to the Lebombo Mountains and the Mozambique border. The solitary record of C. kraussii from southern Mozambique may in fact be this species. It is characteristic of open forest below cliffs in warm, well-watered places.
Derivation of name and historical aspects: The Roman naturalist Pliny (the Elder), who died observing the eruption of Vesuvius in AD 79, wrote about a plant called Combretum. There seems to be scope for considerable doubt as to what he meant by this name, as Smith & Stearn (1963) indicate a climber of unspecified identity, and Lewis & Short (1879) suggest a rush, possibly Juncus maximus. It seems that the best one can say of this generic name is that it is of classical origin, and its present meaning is completely different to the original one. The specific qualifier woodii is more certain: it refers to the fact that John Medley Wood (founder of KwaZulu-Natal Herbarium) collected one of the earliest specimens of this tree at or near his home at Inanda, near Durban. The exact site of his home has been lost, but is probably just across the Inanda Valley from where the pictures illustrating this article were taken.
The genus Combretum is widespread in the tropics and subtropics, and one or more of its 250 species may be found on every warm continent (and many islands) except Australia. Some 30 species of the genus make their home in southern Africa. C. woodii is one of these, and belongs to a group of closely-related and sometimes indistinguishable species including C. kraussii and C. erythrophyllum.
Ecology: Nothing is known for certain about the pollination of this species, and this may be an area where an interested amateur with plenty of time and patience could make a worthwhile addition to the sum of human knowledge, by observing and identifying visitors to the flowers of this tree, and too many others. The flowers secrete some nectar, and the white, new leaves surrounding them are conspicuous even to human eyes. One can only wonder how they appear to insects, which see in the ultra-violet as well. One may guess that this bushwillow is insect pollinated, but no further details are known. The four wings that are characteristic of Combretum fruits may be assumed to play a role in the dispersal of seeds. How effective this role is, may be open to question, as the vast majority of Combretum fruits I have seen in the field, have fallen within a very small distance-scarcely out of the canopy-of their parent trees.
Uses and cultural aspects: As this tree is so closely similar to C. kraussii, the uses are very much the same, if only due to the users confusing the taxa when seeking material to use. Pooley (1993) informs us that flexible young stems may be used for basket-making, and that the wood is tough and yellowish. There is a report from Mozambique that the sawdust (thought to be of C. kraussii ) is an irritant, and it would seem prudent to assume the same of the wood of C. woodii. Tree enthusiasts in the Durban area propagate this species from seed for horticultural purposes.
Growing Combretum woodii
As trees of this species are not inordinately large, they are desirable features of gardens of almost any size. Not only do they yield good shade in summer, but the new leaves and fruits are very attractive, the latter serving equally well in dried-flower arrangements.
Probably the best detailed account of the propagation of this and indeed almost any other southern African Combretum is to be found in Carr (1988). He reports that the seeds of most species of this genus will survive for at least a few years between ripening and planting. Fruits of many species of Combretum are heavily parasitized in the field, but the present species seems to be less susceptible to this than most. Fruits oozing gum, or with a small round hole near one end, should be avoided; of the rest, those which float in water are also beyond hope of germination. Seed should be taken out of the fruits and soaked for a few hours before planting; Carr says that they take one to three weeks to do so, and he recorded a roughly 50% germination rate. His experiments suggest that young plants are not drought-tolerant, but they are capable of withstanding remarkable levels of cold, considering that they occur naturally in frost-free places. He reports problems with aphids, but elsewhere recommends any proprietary systemic insecticide as a remedy for this. Trees grow quite slowly at first, especially when water is a limiting factor.
References and further reading
- Carr, J.D. 1988. Combretaceae in southern Africa. Tree Society, Johannesburg.
- Lewis, C.T. & Short, C. 1879. A Latin dictionary. Oxford University Press, Oxford. [This has been reprinted many times in the century following publication.]
- Pooley, E. 1993. The complete field guide to trees of Natal, Zululand and Transkei. Natal Flora Publications Trust, Durban.
- Smith, A.W. & Stearn, W.T. 1963. A gardener's dictionary of plant names. Cassell, London.