Welwitschia(redirected from Tree tumbo)
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(Welwitschia bainesii, W. mirabilis), a gymnospermous dioecious plant of the Welwitschiaceae family. The single representative of this family grows on the infertile rocky soils of southwest Angola and in the Namib and Kalahari deserts. The long powerful roots of the welwitschia reach to the level of the ground waters. The stalk is low and thick (to 1.2 m in diameter) and columnar; its greatest part is hidden in the ground, with only a small portion (to 0.5 m) emerging above. The upper part of the stalk is more or less saddle-like or bilobate with thong-like leathery leaves (to 3 m long) along the edges of the laminae. The leaves are retained until the end of the plant’s life (100 years and more). On adult plants the leaves break into ribbon-like strips.