Dog’s ears  (Cotyledon orbiculata)

Variety Cotyledon orbiculata oblonga is classified as Lower Risk / Least Concern (LR/lc) in Swaziland on the Southern African Plant Red Data Lists (3). Variety Cotyledon orbiculata flanaganii is classified as Near Threatened (NT) on the Interim Red Data List of South African Plant Taxa (4).

The dog’s ears plant, well known to many gardeners, has handsome greyish-green leaves, with a red or pale margin (2) (5). The leaves are thick and succulent, and vary in shape from flat and rounded to almost finger-like (5). The flowers of this shrub, which hang down from the stem, are tubular structures with petals that curve out at the tip (2) (5). These bell-like flowers vary in colour, and may be deep red, pale orange or pink (6). The tall stems that bear the flowers were once used as flutes by early hunters, to mimic the call of a young klipspringer to lure adults within range of their arrows (5).

This species has an extensive distribution, from south-western Angola and Namibia to South Africa. In South Africa it occurs from the Cape Peninsula across the southern Karoo and Free State into the eastern provinces (6).

The dog’s ears plant grows on sandy or stony soils in coastal and inland scrub (2) (5).

The vividly coloured flowers of the dog’s ears, which appear in September until December (2), advertise the plant to birds and bees, which flit from flower to flower as they feed on the rich nectar (7). Pollination is believed to be carried out by sunbirds (8), a group of birds with narrow, pointed, downward curving bills (9), suited to probing flowers for nectar.

While light is essential for plants, excess light can be damaging. Under the bright southern African sun, the dog’s ears plant has evolved a mechanism to protect itself against damaging excess light. The leaves produce wax that reduces absorption by up to 50 percent, by increasing the reflective properties of the leaves (10). The wax produced by the leaf also helps prevent uncontrollable water loss (11), an important measure for plants growing in warm, dry conditions.

Dog’s ears plants also have properties which make them valued by humans. The succulent leaves of the dog’s ears are used medicinally, for the treatment of warts and abscesses (8), and when heated, the leaves form a substance used to treat boils and inflammations, particularly earache (7). Surprisingly however, animals that graze on this seemingly innocent plant may suffer from cramps, resulting occasionally in death (5).

While one variety of dog’s ears (Cotyledon orbiculata var. flanaganii) is classified as Near Threatened on the Interim Red Data List of South African Plant Taxa (4), there is, at present, no information indicating what threats this species it may face. It is apparently, in some areas, a widespread and common species (3).

At present, there are no specific conservation measures in place for this species. However, even if threatened in the wild, dog’s ears are a frequently cultivated species (8), and these populations will act as an insurance against this species extinction.

For further information on dog’s ears see:

• PlantZAfrica:
  www.plantzafrica.com