Pelargonium alternans J.C.Wendl.
Common names: Blomkoolmalva, koolmalva (Afr.)
The compact growth of the blomkoolmalva makes it an ideal specimen for a bonsai.
The blomkoolmalva is a summer deciduous shrublet with dense succulent branches. It grows up to 400mm with pinnate leaves which are covered with white hairs.
The white to very light pink flowers appear from late April to January and in cultivation it can flower throughout the year, peaking in autumn and early summer. The typical geranium flowers that are 15mm in diameter have fine pinkish purple lines on the petals and orange stamen. The single branch of the inflorescence bears one to four flowers each. Pelargonium alternans has a long flowering period and it is therefore difficult to predict when the seeds will be ripe. The blomkoolmalva also has a well-developed root system adapted for growing between rocks.
Pelargonium alternans is Red-Listed as Least Concern since the populations are stable and occur over a large area.
Distribution and habitat
Pelargonium alternans is found in the dry areas of the southwestern Cape, occurring from the Bokkeveld Mountains to Prince Albert. It grows in the Succulent Karoo with its hot summers and an average annual rainfall of 100-200mm, mainly in winter.
In the Karoo Desert National Botanical Garden it grows in the rocky scale, but it also grows on quartzite, dolerite, granite and tillite.
Derivation of name and historical aspects
The generic name Pelargonium is derived from the Greek word pelargos , which means stork. The name refers to the shape of the seeds that looks similar to the bill of a bird. The species name alternans is Latin for alternating, referring to the alternately arranged leaflets of the leaves.
It is not known exactly when this species was first discovered, but has been known since the 1790s. This genus contains about 270 species, of which 219 occur in southern Africa. The genus is widespread in southern Africa, occurring south of the Sahara and mostly in the winter rainfall region of the Western Cape. The genus includes well-known species such as the lemon-scented pelargonium, Pelargonium citronellum.
The blomkoolmalva occurs in the hot and dry Succulent Karoo. The seeds of pelargoniums have adapted to these environmental conditions by germinating over long periods of time, ensuring that some seeds germinate in favourable conditions. Animals are fond of the leaves and when the area is dry they will eat the stems as well.
Pelargonium alternans is suitable for bonsai culture.
Growing Pelargonium alternans
Pelargonium alternans is easily cultivated from seed or leaf cuttings. The best time to take the cuttings is in autumn or spring. Take 50mm cuttings from new growth, place in sandy soil and keep moist. It should be planted in well-drained soil in a sunny spot. Little watering is required in the growth period from autumn to spring - in summer rainfall areas it will do fine if planted in sandy soil, but the plant will not go dormant. Harvest the seed when ripe and sow in autumn.
Sow the seeds in sandy soil mixture and cover the seeds with 3mm of sand. Germination takes place within 6-8 days. Keep the soil moist, but care must be taken not to overwater. When the seedlings are about 30mm high they can be transplanted. The blomkoolmalva is a drought-resistant plant and do not need much water and will quickly respond to a small amount of water.
- Barkhuizen, B.P. 1978. Succulents of Southern Africa. Purnell & Sons Publishers, Cape Town.
- Jackson, W.P.U. 1990. Origin and meanings of names of South African plant genera . UCT, Rondebosch .
- Van Breda, P.A.B. & Barnard, S.A. 1991. 100 Veld plants of the winter rainfall region. Department of Agricultural Development, Pretoria.
- Van der Walt, J.J.A. & Vorster, P.J. 1981. Pelargoniums of Southern Africa Vol. 2. Juta, Cape Town.
- Vlok, J. & Schutte-Vlok, A.L. 2010. Plants of the Klein Karoo. Umdaus Press, Hatfield.
Karoo Desert National Botanical Garden
Plant Type: Shrub, Succulent
SA Distribution: Western Cape
Flowering season: Early Summer, Autumn
Flower colour: White, Pink
Aspect: Full Sun
Gardening skill: Average