The Phyto-Philes: Mountain Aloes
Created | Updated Apr 16, 2013
Mountain Aloes
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.'
Today I bring you a plant I know very well. The Mountain Aloe, Aloe marlothii (named for botanist H. W. Rudolph Marloth), is a species that is superabundant where I live. It forms stands of thousands of individuals in some places. One notable stand is on a hill to the east of the suburb where I live; another is in the Polokwane Municipal Game Reserve, another still at the Bakoni Malapa Northern Sotho Museum, and there are many others more. This aloe can indeed be found over most of northern South Africa; the southernmost ones occur in central Kwazulu-Natal and differ a bit from the ones we have up here. Mountain Aloes generally occur in hilly or rocky terrain, but not always – the stand in the game reserve, for instance, is on level terrain in savannah. These stands actually seem to exist because of Ndebele settlements dating to the nineteenth century … the people planted aloes for various uses. The Boers ‘conquered' the Ndebele leading to the abandonment of the settlement in 1855, and so the really big ones are over a century old! This aloe is one of the largest species, qualifying as a tree: it can reach 6 m/20 ft in height. The first photo shows me between two large specimens in the game reserve; I've seen ones even taller.
The Aloe genus includes hundreds of species and contains an amazing diversity of kinds. Most are small … some of the smallest reach only about 5 cm/2” in height. At the other extreme is the Tree Aloe, Aloe barberae, which reaches 18 m/60 ft in height with a trunk 3m/10 ft in diameter. Compared to that one the mountain aloe is not very big, and has a rather thin trunk, although in old specimens it thickens into a wide kind of buttress just above ground level. The very thick and spiny leaves reach a length of about a metre/yard, and in the dense stands plants can be very close to each other, sometimes squashed together. The fresh, living leaves are at the top of the stem, while old, hard, dry leaves are retained below it in most specimens, forming a ‘beard' covering the trunk. This ‘beard' of dry leaves can protect the trunk against frost and also against fire. Nevertheless it is not essential. In many places in South Africa people gather these dry leaves from the aloes, using them as kindling for fire, and the trees show none the worse for wear. The second photo shows an aloe with a ‘trimmed' trunk, on another group of hills not far from my home town. This also allows you to see the thickening of the lowermost portion of the trunk. This was taken in late winter; the leaves turn reddish-brown at this stage, and the orange flowers are produced in branched inflorescences above the leaf rosettes.
These aloe flowers are perhaps the greatest contribution this species makes to the local ecology. In winter in the South Africa savannah there's not much to eat, especially towards the end when there has been no rain for several months. It is precisely at this time that the mountain aloe produces its flowers. During the rainy months it has been storing water in its succulent leaves and producing nutrients by photosynthesis, so that at this time it has enough reserves not only to produce the flowers but also to supply them with rich stores of nectar and pollen. And because these aloes grow in such large groups, they constitute a major food source. When the flowers emerge, they will be visited not only by dedicated nectar-drinking birds such as sunbirds, but by almost all other kinds of birds: weavers, bulbuls, orioles and more. At this time you might find birds sporting coloration they lack at other times. As a beginning bird watcher I can remember being puzzled by seeing weaver birds in winter with bright orange on their faces; at this time they usually lose their bright yellow and orange colours, going into their cryptic brownish winter feather coats. Only later did I realize I was seeing weavers with their faces stained by the orange aloe nectar and pollen!
This aloe species can in fact be recognized by its flowers. There are other aloes that are similar in size and shape, but the mountain aloe is the only one producing orange flowers in branched flower heads where the flower ‘spikes' stand sideways at an oblique angle. They're also slightly curved. You can see that in the second aloe photo and also in my painting showing the flowers up close. The individual flowers are tubular, with the tips of the anthers (the male parts producing the pollen) sticking out. Some mountain aloes vary from this typical form, having flowers that are yellow or deep red, but still the same flowerhead shape. But the Kwazulu-Natal form differs, having more upright flower spikes. But they can be recognized by still being less upright than those of Aloe ferox which occurs in the same region, and by having spinier leaves.
Animals and birds appreciate more than just the flowers of this aloe. The tough, thorny leaves are eaten in times of food scarcity by animals like the Kudu antelope. Although the old, dead leaves may appear untidy, they offer excellent protection to small birds like warblers, cisticolas and prinias that make their nests amidst them. The trunk itself is not made of real wood, but woody fibers, and can be excavated with fair ease by birds such as woodpeckers or barbets. These nest holes can later be taken over by other cavity-nesters such as kingfishers or hoopoes.
This aloe can easily be grown from seed, which can be obtained from the dry seed capsules in spring. Fortunately these aloes already flower when still smallish, because on a tall one the capsules at the top of the inflorescence would be very hard to reach! The seeds are flat and papery, adapted to be distributed by the wind. They should be sown on river sand, and a thin layer of sand sprinkled over them. Keep them moist and in light shade in a warm environment. When the tiny seedlings emerge you might treat them with a fungicide to prevent them damping off; continue keeping them moist but not wet. When the small rosettes form, taper off the watering; young plants could be watered lightly once a week. Mature plants don't need much water and prefer loose, well-draining soil with a bit of compost in it. When established in the garden they will thrive on moderate summer rainfall and entirely dry winters – they can survive six months or more of drought in the wild. Indeed they prefer dry winters and shouldn't be overwatered in spring and summer either. Mountain aloes prefer sunny positions, and can tolerate moderate frost.
