The Victoria Falls is a Natural Wonder of the World, not just because of its unique geology and location within the wildlife-rich Zambezi Valley. The “Smoke that Thunders” provides a unique environment for plants. There are nearly 150 tree/tall shrub species occurring in the area, plus over 50 shrub and 150 field/herb species. Together with grasses, sedges, ferns and other groups the total is over 400 plant species.
Although in ecological terms, the Victoria Falls rainforest is not strictly speaking a rainforest, the persistent spray from the waterfall, particularly on the Zimbabwean side, has resulted in a unique micro-climate in which has evolved an interesting and unique floral ecosystem.
Some of the tree specimens in the spray-soaked forests along the lip of the falls , within the Victoria Falls National Park , are identified with small metallic name plates, visible from the paths. The most significant tree species here are the large and striking African Ebony (Diospyros mespiliformis) with its straight trunk and dark bark, the Natal Mahogony (Trichilia emetica) and the smaller African Olive (Olea africana).
There are two types of Waterberry (above) - (Syzygium guineense and Syzygium cordatum), a tree typical of the seasonally-flooded margins of the Zambezi river above the Falls, and the Red Milkwood (Mimusops zeyheri).
Other tree species include the Wild Date Palm (Phoenix reclinata), the hairy leaved Cape Fig (Ficus capensis) and the strangling creeper (Ficus ingens) which eventually kills the tree on which it grows.
Hanging vines, thick shrubs, creepers and a rich variety of flowers and ferns are to be found.
The spray from the falls particularly favours smaller moisture-loving plants, especially the herbaceous ground flora which contains some rare and unique species, adapted to the almost constantly saturated conditions, which are of greatest interest to botanists.
The early rains in November bring the spectacular ‘fireball lilies’ (Scadoxus multiflorus), with their large round globes of red slender flowers also known as ‘red hot pin cushion’.
There is also the national flower of Zimbabwe, the Flame Lily (Gloriosa superba) (left), a shrub layer creeper with red and yellow flowers.
Ferns, notably the maidenhair (Adiantum capillus-veneris) and the near endemic Cheilanthes farinose (pictured below), with its striking sulphur yellow under-surface to the fronds, can be found throughout the rainforest area at any time of year.
The latter species is known only from the vicinity of the Victoria Falls and a couple of nearby sites upstream.
The shrub layer includes Feretia aeruginescens, a straggling shrub producing clusters of delicate white-pink flowers and spherical red fruit.
Pavetta cataractarum produces masses of tubular white fragrant flowers, and
Hibiscus calyphyllus produces a large yellow flower typical of the Hibiscus family (below).
Throughout the year, it is possible to find flowering examples of the bright yellow flowered little Gentian (Sebaea barbeyana), the blue flowered Lobelia spp and the bright mauve flowers of Nesaea floribunda.
In December the ground orchid Calanthe corymbosa develops its large white flowers, the wild gentian (Chironia palustris) adds its pink flowers.
A problem for both the Zambian and Zimbabwean authorities in the World Heritage Site is the ‘alien’ (non-natural to the area) species, the Lantana camara.
The plant was introduced from South America as an ornamental garden creeper, and is a highly aggressive species which out-competes the local indigenous flora. Without active management, it is overtaking large areas of the Victoria Falls park to the exclusion of the natural species. Another alien invader, the Sword Fern (Nerphrolepis cordifolia) is also of increasing concern
Away from the river
Near the David Livingstone statue, and upstream from the Falls, basaltic soils tend to support either Mopane woodland (Colophospermum mopane) or mixed Mopane scrub. These tree species are under constant attack by elephants and only a few specimens of mature Mopane trees can be seen.
Along the Zambezi River above the Falls, riparian woodland species (such as the Waterberry and tall Wild Date Palms are found.
There are also Sausage Trees (Kigelia africana), with large, pendulous, sausage- shaped seed pods, and flood-tolerant river-margin plant species such as reeds (Phragmities mauritianus) and papyrus (Cyperus papyrus).
The famous Victoria Falls 'Big Tree' is a Baobab (Adansonia digitata).
It is not the largest of its kind at all, although it is an old and impressive specimen, measuring just under 17metres in diameter. It has been suggested that this tree could be between 1500 to 2000 years old. It has seen a great deal of history, and attracts many African myths. This venerable botanical specimen should be treated with the respect it deserves.
Downstream of the falls, where the steep rock walls of the gorges can support growth, there is mixed deciduous woodland with plenty of Paper Bark trees, whose smooth papery bark peels off in thin layers. The Paperbark Corkwood (Commiphora marlothii) is the most common.
On the drier, more exposed, rock faces, only aloe species can grow, notably Aloe chabaudii and Aloe cryptopoda.
The rugged slopes of the Batoka Gorge are favourable habitats for two rare and localised tree species - Entandrophragma caudatum (The Wooden Banana – so called because its seed pod, a woody capsule which splits into five valves curving backwards, resembles a peeled banana) and the Propeller Tree - Gryocarpus americanus .
Of the shrub species found in the gorge, Balaria matopensis is locally abundant on the upper slopes and is identified by its attractive blue flowers.
With acknowledgements to Pete Roberts and his fascinating website www.tothevictoriafalls.com