Red Disa
Created | Updated Feb 17, 2013
Red Disa
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.'
Having featured a beautiful flowering plant in the last installment, I decided to do it again. This is the Red Disa Orchid, Disa uniflora, which occurs in the Western Cape Province. It is in fact the emblem of the Western Cape also known as ‘Pride of Table Mountain’; it is also the emblem of the South African Mountain Club and the Western Province Rugby Union. It is named Disa in honour of a legendary Swedish heroine who saved many people from an intended ‘cull’ by meeting a seemingly impossible challenge: she had to meet the king neither on foot nor on horseback, not in a wagon or boat, not dressed or undressed, not within a month or within a year, not by day or by night, not while the moon was waxing or waning. She came to the king on a sled drawn by men, with one leg in the sled and another over the back of a goat running beside the sled; she was wearing a fishing-net; she came at dusk on the third day before Yule which by the traditions then was counted as an ‘extra’ day falling between two years. The Disa orchids were named after her for the net-like pattern of veins in their upper sepals.
While the Impala Lily of the previous installment belongs to the Dicotyledons, the orchids are members of the other big branch of flowering plants, the Monocotyledons, like the true lilies. The Orchid family is perhaps the most species rich and diverse of all plant families. Many beautiful species occur in South Africa. The Red Disa is one of the most striking of all. It bears large red flowers on long stalks; the species name uniflora means ‘single flower’, even though more than one flower might sometimes be found on a plant. Other (but not all) species of Disa bear inflorescences containing many flowers. The Red Disa’s flower stalk can reach 60 cm/2’ in height, while the flower reaches 12 cm/about 5” in diameter. Today about a hundred and seventy different species of Disa are known, most from South Africa, a few reaching tropical Africa.
Although called ‘red Disa’, the flower is not always red, but sometimes pink or even yellow. Although it looks simple it is, like all orchid flowers, highly modified from the general simple, radially symmetric flower shape. The upper sepal is formed into a ‘hood’ standing over the two lower sepals. The actual petals are small, and the male and female reproductive parts are fused together into a single column or gynandrium. This releases the pollen, which come in packages or pollinia which contain many pollen grains bound together by a sticky substance; when a butterfly comes to drink nectar, these pollen packets stick to it and are carried to a different flower where, if all goes well, it will get stuck in the right place, thus pollinating it. The Red Disa is pollinated by the beautiful Mountain Pride butterfly. This butterfly is unusual in insects for being able to distinguish the colour red, to which it is drawn whether in flowers or in the clothes of hikers and mountaineers. A consequence of this colour attraction is that the occasional mutant yellow flower form of this Disa does not get pollinated and is therefore very rare.
These exquisite plants only grow in very moist places such as next to waterfalls or streams where there is a constant spray or seeping water. They also typically grow in shade, although some light is good to stimulate flowering. Their natural distribution is restricted to the moister parts of the Western Cape, and in the Winter rainfall region. They also like a cool environment, frequently growing high up in the mountains. The plant itself consists of a simple tuft of leaves growing from a small underground tuber. The flowers emerge in Summer, with a peak during February, which is the dry season in its native habitat. They are fairly long-lasting, in order to give them the best chance of getting pollinated. After flowering, the plant dies back and underground runners or stolons form new tubers from which new tufts grow.
Disas like all orchids are protected by law in South Africa and may not be grown without a permit. I don’t have any of them in cultivation at the moment, but there are people in South Africa (and elsewhere) who do grow them. They can be multiplied by division of the underground tubers, something that happens naturally as mentioned above. A more sophisticated method is growing them from the seeds, which are fairly large compared to those of other orchids, and perhaps adapted for dispersal by water. The seeds should be sown on peat or sphagnum moss placed over coarse river sand. The seeds should initially be moistened with a fungicide. The pot in which the seeds are sown should then be covered with glass or plastic and left in a shady position until germination starts. Then the medium is best moistened by standing the pot in shallow water. When the seedlings are a suitable size the plastic or glass cover can be removed and they can be picked out and planted individually. For this species a slightly acidic soil is best. They flower at around three years and from then on should be repotted after each flowering, the stolons and roots being carefully washed before being placed in the new medium. Plants must be watched for signs of fungal infection or rot, and treated with fungicide when necessary. They respond well to feeding with liquid fertilizer. All in all, not an easy plant to grow, but very rewarding if this is successful. More detailed advice on cultivating this species can be found here.
But in the end, these plants are best enjoyed in Nature. They add to the beauty of the lovely Cape Mountains, growing in these beautiful sheltered places that are little gardens of mosses, ferns and flowers. Coming across just a single one in flower is a delightful experience, and sometimes they are found in large clumps bearing dozens of flowers. Thankfully these mountains are today mostly declared nature reserves and conservation areas; the only significant threats to them, and other indigenous flora, is the encroachment of alien plants that may take over parts of their habitat. But presently there are considerable efforts made to curb the spread of these.
