The Phyto-Philes: Karoo Gold
Created | Updated Jul 27, 2014
Karoo Gold or Yellow Pomegranate
This time I have for you a lovely shrub from the desert! The Karoo Gold, also known as Yellow Pomegranate, scientific name Rhigozum obovatum, occurs mainly in the Karoo, which is a large sub-desert region in the south and interior of South Africa. In spite of its alternative name, it is not a pomegranate at all, but belongs to the Bignoniaceae, the family that includes Sausage Trees and the Port St Johns Creeper. Its genus name 'Rhigozum' is derived from the Greek word 'rhigos' which means 'rigid'. It refers to its stiff, twiggy growth habit. The species name 'obovatum' comes from Latin and means egg-shaped, which refers to the shape of the small leaflets.
Treasure of the Desert
The Karoo is a bleak landscape. Most of it is a vast flat plain, from which flat-topped hills, similar to the mesas of the American deserts, rise here and there. The soil is mostly rocky rather than sandy, and the region, especially the more high-lying, deeper inland parts, can experience extreme winter cold in addition to extreme summer heat. Most of the vegetation consists of low, scrubby growth, with hardly anything that can be called a tree, and coarse grass.
In this landscape it is remarkable to find beautiful and delicate flowers such as these. Indeed, there are many other beautiful flowers that can be found in the Karoo at just the right time. Usually the flowers appear in response to favourable events, most typically abundant rainfall – something that does happen, but very infrequently. The Karoo Gold usually flowers in Spring, and will produce its best displays after periods with ample rain.
The flowers of the Karoo Gold are trumpet-shaped with flaring, delicate petals. These are bright yellow, and in good conditions can completely cover the shrub. They are about 3.5 cm/1.4" in diameter. These flowers attract butterflies and other insects as pollinators. After pollination, the flowers drop off and the fruit develop. These are long, flat pods, brown to purplish, that split open to release the flat, papery seeds that are distributed by the wind.
Most of the year, the shrub will be without flowers. It is then not very noticeable amidst the rest of the scrubby desert vegetation. They can grow into small trees 4.5 m/15' in height, but seldom become that tall. They are extremely popular as food for browsing mammals, game as well as domestic goats and sheep. These often browse the shrubs down to less than a metre/yard in height. They are consequently rather scruffy-looking most of the time. Game will browse the flowers and pods as well.
The plants can grow much bigger and become more showy when they grow in protected places, such as on steep hill slopes. When not in flower, they can be identified on their shape, with their stiff branches and twigs that are arranged in opposite pairs. The bark is greyish and smooth. The twigs often end in spiny tips. The leaves are very small, greyish green, and either simple or compound, with three leaflets on a short stem.
This shrub grows mostly in stony ground. Apart from South Africa, it also grows in southern Namibia. A couple of populations have been found growing well away from the Karoo, in the grassland of the Highveld and in dry savannah in the Sekukuniland region of the Limpopo province. The genus Rhigozum contains a few other species of small tree and shrub also found in South Africa, being characteristic of semideserts and dry woodlands.
Growing the Karoo Gold
It is easy to grow this plant from seed. These should be sown on well-draining soil and covered with a thin layer of sand. Keep them moist and in a warm place until they germinate. The young plants grow slowly, growth rate picking up when they're planted out and established. Although not liking lots of water, they appreciate rich, fertile soil. This is an excellent choice for a rock garden with succulents and other xerophytic1 plants. The Karoo Gold prefers growing in full sun. It can take moderate frost and ought to grow well outdoors in the drier parts of southern Europe and the southwestern USA. Where the climate is too cold or wet, it can be grown in a hothouse, on a sunny patio or in a pot on a sunny windowsill. It is a great species for training into a bonsai.
