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
This Streptocarpus occurs only in a limited area of Western Cape, confined to the Winterberg and Elandsberg mountains. This species grows rooted in soil as well as wedged in rock cliff crevices above the forests. It is found in quite dry shaded habitats.
Derivation of name and historical aspects
The name Streptocarpus is derived from the Greek words, streptos, meaning twisted, and carpus meaning fruit, which is a perfect description of the plant's spirally twisted seed pods.
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. This is a large family of mostly tropical and subtropical herbs, with ± 139 genera, and ± 2 900 species world-wide. There are eight genera in Africa, with the one genus, Streptocarpus in South Africa. Streptocarpus has ± 45 species in South Africa, occuring mainly in the eastern half of the country, usually in cool, moist habitats.
The family is named after Swiss scholar, Konrad Gesner. In 1963, 30 years after his death, his name was given to this family. In 1826 the collector James Bowie took the first plants of Streptocarpus rexii to the Royal Botanic Gardens, Kew in England.
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.
Uses and cultural aspects
Some species of Streptocarpus are used in Zulu medicine where leaf infusions are drunk to ease labour pains.
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.
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 overwatered 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 to wilt slightly between each watering and they have the ability to recover very well from this. Be aware that severe wilting can be a sign of root rot caused by overwatering 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 during growing season with liquid foliar feeds 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 warmth 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 30 mm 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 mealybug 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 mealybug.
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 only prone to pests and diseases when they are not being treated or grown correctly, as any plant that is stressed is more likely to come under attack. So avoid the following to reduce the occurrence of problems: overwatering, underfeeding, rootbound plants, lack of good air movement/circulation.
References and further reading
- 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 .