Quiver Trees, Part 2
Willem says: 'The Phyto-Philes are for plant lovers of every size and shape, colour and flavour. As with my Colours of Wildlife column, I'll be featuring one species per article, illustrated with sketches, paintings, and/or photos. Over time I hope to be showcasing the amazing diversity of weird and wonderful plants that occur in South Africa, while also from time to time looking at the flora of other countries. While featuring many spectacular species, I'll not be neglecting the smaller, more humble kinds that are nevertheless fascinating in their own right.'
Quiver trees grow in semi-desert regions. They grow slowly and large specimens can be very old, perhaps a century or more. Being some of the largest trees in their native regions they are used by one of the most interesting of birds, the Sociable Weaver, Philetairus socius. These little birds construct huge nests that look like haystacks flung intact into the trees. The vast mass of grass shades and shelters the ‘living rooms’, individual nest cavities, the entrances to which which are found at the nest’s bottom. These are difficult to reach by predators. Interestingly a small type of predatory bird, the Pygmy Falcon, Polyhierax semitorquatus, (which is only slightly larger than the weavers themselves) often nests amidst them, apparently without causing a bother. Also, the lovely local lovebirds, Agapornis roseicollis, often move into a nest after a pair of weavers have moved out. So, by supporting these huge nests the quiver trees are actually sustaining large communities of multiple bird species. Unfortunately the nests can sometimes become so big that they cause branches to break or even the tree to topple!
The first record of this tree was made by governor Simon van der Stel of the Cape Colony, in 1685, on a northward trip. This makes this one of the earliest recorded indigenous aloe species; most of the European colonists back then did not care much to record the flora, but this species is so conspicuous that the governor had to mention it. He also noted its use by local peoples as quivers. The branches have a tough exterior, the bark being quite hard, but the interior is soft and pulpy, easy to hollow out. A section of hollowed-out branch can then be closed off with a patch of leather at one end, and then serve as a suitable quiver for the poison arrows of the San and Khoi peoples.
What is less well known is that entire trees can be used as refrigerators of sorts! If a good section of the trunk of a standing tree is hollowed out, food and drink can be stored inside. The air circulating through the cavity and the fibrous trunk tissue has a cooling effect. Of course it’s not nice to the trees to do that to them!
Quiver trees still occur in substantial numbers in South Africa and Namibia. There are some threats to them, such as people removing wild plants for their gardens, or habitat destruction from farming, overgrazing and mining. Local changes in the water table due to human activities or climate change can also eradicate quiver tree communities. Because these trees are so unique and striking I feel they should be cultivated and planted as much as possible here in Southern Africa. We can plant them back into their natural habitat and also plant them in our gardens. I have several in my own garden, even though they are still small – and likely to remain so for a few decades at least! Quiver trees can tolerate heat and drought but only light frost and don’t like wet soil, which may cause them to rot. But if you cut off the rotten part and let them dry for a few weeks or months you can replant them and they might reroot. Quiver trees can probably be grown outside in much of the Middle East and the arid southwestern USA such as southern Arizona and California. In colder, wetter climates they can be grown in hothouses. They can even be grown in pots on sunny windowsills; they will remain small and grow into unusual little specimens.
The Giant Quiver Tree, Aloe pillansii which I illustrate in the pencil sketches, grows somewhat taller, reaching 10 m/33 ft, but is more sparsely branched. It also carries its inflorescences hanging down rather than erect. It is much more threatened, only growing in the harsh Richtersveld , a desert region in South Africa and Namibia around the mouth of the Orange or Gariep River. It is also much harder to cultivate and depends on being protected in its native habitat.