An ideal water wise ground cover plant for dry gardens, Aptosimum procumbens is one of the treasures of the arid and semi-arid parts of South Africa.
Description
These perennial plants form 'carpets' of up to 1 m in diameter. When in full bloom it is covered with dark blue or violet, trumpet-shaped flowers that can appear at any time of the year but mostly during spring to summer. Leaves are alternate, usually densely crowded on long or short shoots, linear, lanceolate, elongated or spathulate entire. The fruit is a thick-walled capsule opening at the top and often persists after seeds are dispersed.
Distribution
A. procumbens, and other species of Aptosimum, have a wide distribution range from parts of Namaqualand, Bushmanland, the Great Escarpment, the Northern, Upper, Great and Little Karoo, Northern Cape and Namibia. It often occurs in abundance on floodplains, flats, ridges, crowns, disturbed ground and mountain plains.
Derivation of name and historical aspects
The name Aptosimum is Greek in derivation, a meaning not and ptosimos meaning deciduous (which in turn comes from ptosis meaning 'fall') and refers to the fruit, a capsule which is retained on the plant even after the seeds have been released.
Ecology
The trumpet-shaped flowers are clearly designed for insect pollination and the flower petals acts as ideal landing pads. Their shape and colour lead to the assumption that bees are their pollinators. They are 'gullet flowers' which means that the corolla is tubular over the greater part of its length and very narrow in the basal region, protecting the nectaries from all but long tongues or minute visitors. Although bees visit flowers from time to time, it appears that the primary pollinators are pollen wasps (Vespidae, Masarinae), particularly from the genus Celonites. Even more peculiar is that Karoo violets receive more frequent visits from specific species of Celonites in specific distribution localities, C. clypeatus and C. andreis for example, throughout the Karoo. These little wasps, on average about 10 mm long, are blackish and have red or red and white markings. They have long retractable tongues with which they collect the nectar.
Uses and cultural aspects
It is quite surprising that Karoo violets with their striking beauty have received very little horticultural research, as they really show great potential as garden plants especially in the dry parts of the country. With specific selection and mass cultivation there should be no reason why they can't be used in flower boxes, hanging baskets or ground covers and become just as popular as our pelargoniums, senecios, etc. It is recorded that Aptosimum was cultivated as an ornamental in England from seed sent there by Burchell and Ecklon from as early as 1815 to in about 1828. The plants are said to be of medicinal value and are used to treat krimpsiekte in sheep, an acute and serious sickness that affects the joints, muscles and stomach, often resulting in starvation and ultimately death.
