Cotyledon undulate: Silver Crown, Silver Ruffles
Succulents also include amongst their number plants for the more experienced grower. The genus Cotyledon is definitely not one for the beginner for it includes rarities, that, though beautiful, are very sensitive.
The approximately 45 species that make up the genus are distributed chiefly in South Africa. They are divided into two basic groups. The first has a thickened stem and small deciduous leaves and includes, for example, Cotyledon bucholziana, C. reticulata, C. pearsonii and C. ventricosa (the last two are extremely poisonous). The second group, which includes the species, has larger leaves with a thick chalky bloom.
In the wild C. undulata forms branching shrublets, in cultivation usually a single stem about 50 cm (20 in) high. The leaves are up to 12 cm (4-3/4 in) long and very wavy on the margin. The bloom is particularly evident on the margin, which is snow white. The, only about 2.5 cm (1 in) long and coloured golden orange, are carried on a stem that is about 35 cm (14 in) long.
Though in the wild (in Cape Province) Cotyledon undulata grows on laterite soils, in cultivation it is better to provide a lighter but nourishing mix such as John Innes potting compost No. 1 with extra sharp sand added. It also does well in crushed brick, with nutrients being provided with the water (hydroponic cultivation). This has the added advantage that the plant need not be transplanted and there is far less danger of rubbing off the beautiful but delicate chalky bloom. This could also be damaged by water and so the plants should always he watered from the base and never syringed.
In winter the temperature must be reduced but at the same time the plant should be provided with as much light as possible. If one is successful with this plant, then it is worth trying to propagate it, either by cuttings or simply by inserting whole leaves in a sand and peat compost. This is easier, and not as lengthy as propagation from seeds.
C. undulata mucronata is a pretty variety which has smaller leaves with a reddish-brown margin.