Welwitschia
Welwitschia is the sole member of the gymnosperm family Welwitschiaceae. In a private letter to ‘Darwin’s bulldog’, Thomas Huxley, Joseph Hooker, director of the Royal Botanic Gardens, Kew, described it as ‘out of all question the most wonderful plant ever brought to this country – and the very ugliest’.
Welwitschia is restricted to a coastal band of the Namib Desert, some 100 kilometres wide, extending from southern to western central Angola. The area is extremely arid, with annual rainfalls ranging from zero to less than ten centimetres that are concentrated in a three-month ‘wet season’. Welwitschia plants, which are thought to live for millennia, obtain their water from heavy dews and deep groundwater resources.
The plant first came to European attention through the prolific African collecting activities of the Austrian botanist Frederich Welwitsch, who was employed by the Portuguese government to collect plants in their Angolan colony. During the last 160 years, Welwitschia has been the subject of extensive scientific debate, although the Portuguese government did not get the economically useful plant it desired. Hooker honoured Welwitsch in the plant’s scientific name.
Each Welwitschia plant comprises two, parallel-veined, leathery, ribbon-shaped leaves that are arranged around the margin of a flat, two-lobed, woody crown, which Hooker described as ‘like the burnt crust of a loaf of bread’. The leaves, which grow continuously and reach lengths of up to four metres, are usually frayed at the tips. Specimens rarely rise more than about one metre above ground. Below ground, Welwitschia has a woody taproot that extends deep into the soil, and an extensive network of lateral roots. Welwitschias occur as separate male and female plants, with the reproductive structures produced around the rim of the woody crown. The plant’s appearance is reported to have provoked Welwitsch to remark that it was ‘so overwhelming that he could do nothing but kneel down on the burning sand and gaze at it, half in fear lest a touch should prove it a figment of the imagination’.
Soon after the discovery of Welwitschia, it was proposed that since the plant only produced two leaves it persisted as a ‘giant seedling’, leading to it being described as a ‘Rip Van Winkle among seedlings’. Anatomical research led to the rejection of the giant-seedling idea, producing the evidence to show that the plant’s form is a consequence of the loss of the main growing tip at an early developmental stage.
Further reading
Bustard L 1990. The ugliest plant in the world: the story of Welwitschia mirabilis. Kew Magazine 7: 85-90.
Cooper-Driver GA 1994. Welwitschia mirabilis – a dream come true. Arnoldia 54: 2-10.
von Willert DJ 1995. Welwitschia mirabilis – new aspects in the biology of an old plant. Advances in Botanic Research 2: 157-191.
Stephen Harris