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Tucson Cactus and Succulent Society

Growing Succulents in the Desert Column, June 2010

(List of Growing Succulents in the Desert columns)

Welwitschia

By Mark Dimmitt

(This article may only be reprinted with the permission of the author)


Almost any plant nut will agree that welwitschia is among the top two or three strangest plants on the planet (Figure 1). Also one of the ugliest. But the plant becomes more fascinating the more you know about it. There is a single species, Welwitschia mirabilis (W. bainesii is a synonym), and is the only species in its family and order (in other words, it has no close relatives). It’s a conifer, and technically a woody tree. Its closest (rather distant) relatives are Ephedra (which includes Mormon tea and ma huang), and a tropical liana, Gnetum. The plant is native to the Namib Desert in Namibia and Angola. Big plants, which may be more than a millennium old, look like stranded octopuses. The bizarre growth habit of Welwitschia accounts for its strange appearance. Seeds germinate in a normal way, and produce two cotyledons (seed leaves), soon followed by the first pair of true leaves (Figure 2). Then the apical meristem dies! The plant can produce no more leaves for the rest of its life. Instead, the two straplike leaves lengthen and widen from their bases for as long as the plant lives. Eventually the leaves split lengthwise; thus old plants may appear to have more than two. They die and fray at the tips; the living portion may be a meter or more long.

CULTURE

Small seedlings are susceptible to damping off, but once a plant is a few months old, Welwitschia is very easy to grow. There are only two important things to know. First, protect it from hard freezes. Second and most critical, NEVER let it dry out. In a small pot it will die almost overnight if the medium dries out. That’s because Welwitschia is NOT a succulent. It has no water storage organ. In habitat the roots go very deep and access permanent moisture, much like mesquite trees. Ernst Van Jaarsveld, horticulturist and curator of the conservatory at Kirstenbosch National Botanical Garden, says that in nature they also have shallow lateral roots that take up moisture from fog. But in cultivation I have never seen anything but roots that go straight down. Contrary to popular myth, a deep pot is not necessary. The roots will wind around the bottom with no problem. However, a large deep pot is beneficial to reduce the risk of drying out if you forget to water it for a few days. Potting medium is unimportant as long as it is well drained. But again, a finergrained medium will dry out more slowly.

Growth rate increases with plant size. Seedlings grow a few inches of new leaf on each side per year. Leaves of larger plants (Figure 3) can elongate a foot per year. I have one in the ground in my yard (Figure 4), and it has done well. On cold nights I cover it with two layers of cloth, and it has survived 17 degrees F (-8 C) with no damage. If you have a Welwitschia on display, it’s sure to be aconversation-starter.

List of Growing Succulents in the Desert columns