This lovely, delicate plant is a jewel in the garden for it flowers abundantly throughout the summer. In the wild it is found throughout the mountainous areas of the northeastern and eastern Free State, Lesotho, the northeastern Cape and the southern KwaZulu-Natal Drakensberg. Above ground the thin stems may look soft and the pink flowers dainty, but they root firmly into rock crevices and gritty soil on the slopes. Finding diascias on these high mountains flowering with geraniums, kniphofias, suteras and dieramas is a magnificent sight.

Diascia integerrima is one of the most widespread, toughest and floriferous of the all the Diascia species. It grows in clumps branching from the ground into many wiry, but rigid stems. Sometimes the square stems can get a bit woody at the base, but they are usually soft and blue-green. The stems are 30-40 cm tall, but grow longer if they have to climb through surrounding bushes. The narrow leaves are mostly at the bottom of the stems, with a few smaller ones towards the top where the fat flower buds hang like little bells. While the bottom flowers open, new buds are continually forming at the tip of the stems and flowers are produced throughout the summer. Close-up these bright pink flowers are very interesting.Typical of Diascia, the flowers have two long horns or spurs at the back of the flower, which has given this genus the common name of twinspurs. The flower is shaped with a large drooping lower lip and four smaller curly petals at the top. At the centre of the flower there is a bright yellow and maroon concave patch called a "window". The pollination of diascias by special oil collecting bees in the wild, is fascinating. These specialized bees have modified forelegs with which they collect oil from inside the two spurs. Once cross-pollinated, little round seeds are formed in capsules. Within a few weeks the seed capsules turn brown and dry, split open and release the ripe seeds that are black and hard.

The genus Diascia contains about 70 species, and is found only in southern Africa. The summer rainfall area of the KwaZulu-Natal Drakensberg is rich in perennial species like Diascia integerrima while about 50, mostly annual species are found in the winter rainfall area of the Western Cape and Namaqualand. The genus name Diascia is derived from Greek meaning di = two and askos = sac, referring to the two oil containing spurs.

Growing Diascia integerrima

At Kirstenbosch, Diascia integerrima has been a firm favourite for summer colour for many years. A delightful evergreen perennial, it is used in pots, rockeries, hanging baskets, to fill little pockets between other plants and in large sweeps in the garden beds. The possibilities for mixing Diascia intergerrima with other summer flowers are endless, whether it is with other perennials like blue Wahlenbergia undulata or mauve Monopsis unidentata; or for a spectacular sight with bulbs like the tall graceful bells of Dierama pendulina or the blue spikes of Scilla natalensis. The bright pink flowers also make a wonderful contrast with the grey foliage of Cotyledon orbiculata (plakkie) or Stoebe plumosa (slangbos). A large pot filled only with a mass of flowering Diascia intergerrima, is also an unforgettable sight.

Diascia integerrima requires a sunny position and well-drained, good garden soil prepared with plenty of compost. Although Diascia integerrima is more tolerant of dry conditions than most twinspurs, it still requires regular watering throughout the year. By the end of summer the plants usually look untidy and they go slightly dormant during winter. Diascia integerrima is quite hardy and will survive low temperatures and heavy frost. If established plants are cut back they will shoot out afresh the next summer, but for the best display they should be propagated and replanted every year. A white flowering form of Diascia integerrima is also available,but unfortunately it is not as tough as the pink.

The easiest way to propagate Diascia integerrima is by cuttings. Select non-flowering growth 5 to 6 cm long, semi-ripe, softwood or young shoots from the base. The best time to propagate is when the plants shoot in spring or cuttings can be taken throughout the summer and autumn. At Kirstenbosch the cuttings are treated with a rooting hormone, placed in a tray filled with a mix of bark and polystyrene and watered with a fungicide. The tray is placed in a mist unit with bottom heat. The cuttings root easily within 10 days.

Diascia species are self-incompatible and, therefore, do not set seed easily in the garden.

Liesl van der Walt
Kirstenbosch NBG
November 2001