Streptocarpus montigena L.L.Britten
Common names: Cape primrose, wild gloxinia
An unusual small pot plant for indoors, with rough, hairy slightly sticky leaves. This is quite a difficult species to grow — providing the discerning home gardener with an interesting challenge.
A perennial herb with a tight flat rosette of glandular hairy, light green leaves. Unusually, no stems are present in this plant so the leaves grow continuously from their bases, all connected by a common rootstock. Each leaf is actually an individual plant with its own roots and flowering stems.
From January to March, long slender flowering stems arise from these same leaf bases and bear 2–6 wide tubular flowers at their ends, each with five broad, uneven petals. E ach flower typically has two lips; the upper is 2-lobed and pale violet, the lower is 3-lobed and creamy white. The lower lip has two pale yellow stripes that blend to a yellow patch deeper into the throat of the flower. The flower stems, petals and buds are all covered with long glandular hairs. The short fruit capsules, velvety to the touch when first formed, twist open in a spiral once dried, releasing numerous lightweight tiny seeds.
Many of the Streptocarpus species are very specific in their distribution and occur in very small populations, making them vulnerable to any disturbance. Streptocarpus montigena is Red Listed as Rare.
Distribution and habitat
Streptocarpus montigena occurs only in a limited area of the Western Cape, confined to the Winterberg and Elandsberg mountains. It grows rooted in soil as well as wedged in rock-cliff crevices above the forests, in quite dry shaded habitats.
Derivation of name and historical aspects
The name Streptocarpus is derived from the Greek word streptos meaning twisted and carpus meaning fruit, which is a perfect description of the plant's spirally twisted seed pods. In 1826 the collector James Bowie took the first plants of Streptocarpus rexii to the Royal Botanic Gardens, Kew in England.
Streptocarpus belongs to the same family, Gesneriaceae, as the well-known African violets (Saintpaulia ) and gloxinias (Sinningia) that are grown as pot plants all over the world. The Gesneriaceae — named after Swiss scholar, Konrad Gesner, in 1963, 30 years after his death — is a large family of mostly tropical and subtropical herbs, with ±139 genera, and ±2900 species worldwide. Of the eight genera in Africa, one genus, Streptocarpus, with ±45 species, is native to southern Africa, occuring mainly in the eastern half of the country, usually in cool, moist habitats.
Gesneriaceae are often epiphytic (growing on trees) or lithophytic (growing on rocks). The plants can cross-pollinate easily with other species but in many instances are self-pollinated. The very small seeds are wind-distributed.
There are a wonderful variety of easy-to-grow Streptocarpus hybrids in all shapes and sizes with really striking flower colours and forms which make very popular indoor plants. Today new hybrids are still being introduced to the huge and growing pot-plant market.
Some species of Streptocarpus are used in Zulu medicine where leaf infusions are drunk to ease labour pains.
Growing Streptocarpus montigena
Streptocarpus montigena is a plant that is seldom seen in gardens due to its unavailability in the trade and because it can be difficult to grow in home garden conditions. It does best as a pot plant indoors rather than planted out in the garden, as it does not like a lot of watering. Ensure a warm spot with good light but no direct sunlight. Windowsills often meet these requirements.
In general, Streptocarpus species are very sensitive to direct light, and are burned easily by the sun. However, they also flower poorly in deep shade. Light shade with good ventilation is best for growing healthy plants with plenty of flowers.
Watering Streptocarpus species should be done with care. It is very important that the plants should not be over-watered, to prevent rotting and fungal problems. They have shallow root systems as in nature they often thrive in very little soil. Therefore, allow them to dry well between waterings — they can in fact be allowed to wilt slightly between each watering since they have the ability to recover very well from this. Be aware that severe wilting can be a sign of root rot caused by over-watering so check the soil to see that this is not the case. Avoid wetting this plant's leaves by watering from the base — pour water into the pot tray, so that the plant and soil can absorb what is required from there. During the warm summers when they are actively growing, the plants need regular watering but note that most Streptocarpus species `rest' during winter and this slight dormancy will cause them to need very little water during this time, so be sure to reduce the amount given.
Regularly remove all dead, unhealthy, dying leaves and flowers as these encourage fungal growth, and to keep the plants looking attractive. Removing spent flowers can often stimulate a second flush of flowers.
The tips of the leaves often die off as they get older, or when stressed by drought or low temperature, or when overwintering. This unattractive tip can be cut off or removed without harming the growth of the leaf as it would naturally shed this through an abscission layer and continue with new growth from the base.
Regular feeding with liquid foliar feeds during the growing season is recommended. Repot once the plant's roots appear at the bottom of the pot.
All propagation is best done in spring which is the start of the growing season. Streptocarpus montigena can easily be grown from seed. Sow by mixing a pinch of the dust-like seeds with a small amount of sand to assist with spreading them evenly. Use a well-drained medium that is not too coarse. Cover with a very thin covering of sand, keep out of direct sun but in a waarm spot and water regularly with a fine spray. Germination usually takes 3-4 weeks; do not allow the seedlings to dry out. Plant the seedlings into small pots only once they are quite big and strong. Transplant the young plants again into bigger pots when the roots have filled the small pots.
Streptocarpus species can be propagated from a single leaf and the best results are from leaf cuttings taken in spring and early summer. A variety of mediums can be used as long as they are well-drained. Sand, bark, palm fibre and polystyrene or vermiculite in different ratios are all suitable. At Kirstenbosch National Botanical Garden, we use 40% bark, 40% polystyrene and20 % river sand. Water the medium well and treat with a suitable fungicide before using.
Select healthy youngish leaves from the centre of the plant and cut off using a sharp knife or blade. Remember that the most active region of the leaf is near the base where the growing region (meristem) is present and so this area will yield the best rooting results. If it is a small leaf, insert the cut end of the leaf into a rooting hormone and then into the medium. Larger leaves can be cut into 30mm strips. Always take note of which way the leaf cutting should be orientated before dipping into a rooting hormone, and place firmly into the medium, but not too deep as this will encourage rot. Alternatively, cut along either side of the midrib and treat in the same manner. Depending on the species, plantlets will form along the base of the cut in 1-3 months.
When the plantlets are well established, the old leaf can be teased out from the medium and the plantlets potted up into a rich well-drained soil mixture, usually between 6-12 months. Plants that have grown quite large can also be divided as a method of increasing them; do this in early spring and repot to grow on. Mature plants can lose their vigour after 3-5 years and propagation as described above can be used to replace them with younger plants.
Mealybug, aphids and caterpillars are the most troublesome pests of Streptocarpus species, though none severely. Caterpillars can either be collected by hand or sprayed with a suitable poison. Aphids can be sprayed or removed carefully by running a thumb and forefinger along the flower stem (where they usually occur). If mealy bug is found on any part of the plant, quickly remove the affected parts and treat with a suitable pesticide. Kirstenbosch has had great success in managing infestations by using biological control with the natural predators of mealy bug.
Fungal infections are also a cause for concern; if fungus is found on any part of the plant, remove the affected parts and treat with a suitable fungicide.
Streptocarpus species are usually prone to pests and diseases only when they are not treated or grown correctly — any plant that is stressed is more likely to come under attack. So, to reduce the occurrence of problems, avoid the following: overwatering, underfeeding, root-bound plants, lack of good air movement/circulation.
- Burtt, B.L. & Hilliard, O.M. 1971. Streptocarpus, an African plant study. University of Natal Press, Pietermaritzburg.
- Hutchings, A. 1996. Zulu medicinal plants. An inventory. University of Natal Press, Pietermaritzburg.
- Leistner, O.A. (ed.). 2000. Seeds plants of southern Africa: families and genera. Strelitzia 10. National Botanical Institute, Pretoria .
Plant Type: Perennial
SA Distribution: Eastern Cape
Soil type: Loam
Flowering season: Early Summer, Late Summer
Flower colour: White, Cream
Gardening skill: Challenging