"I Think That I Shall Never See..."

"...a tree so bizarre as the Desert Kohlrabi."  Words to that effect might well apply to this post, an offering of some of the more unusual trees of the Namibian desert for which I can also provide halfway decent accompanying photographs.  Some of life's most remarkable variations arose in harsh and restricted habitats and shrubs and trees are no exception.

Adenia pechuelii resembles its namesake kohlrabi and is endemic to a band of Namibian semi desert running north from Walvis Bay to central Kunene province.  Another common name for this extremely uncommon plant is "elephant's foot", and indeed its squat, gray-green stem has something of the pachyderm about it.  This plant has woody branches and perches on rocks, like this enormous specimen.  It bears either male or female flowers.

Or consider the highly toxic Euphorbia virosa, whose milky sap means death to many but can be digested by black rhinoceros.  Careless campers who have attempted to burn the wood of this tree have died from the smoke.  It is sometimes used as an arrow poison and is the most venomous, if such a term can apply to a tree, of the euphorbia species.  Spiny succulents, they are unrelated to cacti and are found in the hottest and driest parts of Namibia.  This particular euphorbia grew just beyond our little house at the Grootberg Breeding Station in ≠Khoadi //Hoas Conservancy.

Then there is the Herero sesame bush (Sesamothamnus lugardii), another Namibian endemic. Its stiff, swollen stems and fleshy trunks bear yellow flowers that swell at the base of the tube.  Perhaps for this reason, an extract of the root is used medicinally by the people of this region as a treatment for venereal disease.  Other endemic trees have common names with modern associations. Acacia robynsiana, the radio tree, is so called because its slender, whip-stick stems were used by Afrikaner farmers at remote outposts to suspend their shortwave aerials.  It grows high on mountain ridges from a clump of dense vegetation and then projects its drooping stems as much as 45 feet above the ground.  Because of its atypical form and growth habits it is also called Heaven's broom.  There are two specimens of this tree in the photograph at left, the one of the left with its characteristic stems and a second at the right showing only its shrubby mass at the base.  Far below is a tributary of the dry Kakatswa, or "anus dropping" river.  Plenty of dung there from grazing animals, particularly elephants and goats.

The most unusual tree of the Namib must be Welwitschia mirabilis, truly the missing link between cone-bearing gymnosperms and flowering angiosperms and with characteristics of both groups.  The female cones are clearly visible in this specimen, and if you look closely you can also make out the welwitschia bug, Probergrothius sexpunctatis, that feeds on the sap of the tree and may aid in pollination.  The woody trunk is seldom more than a foot or two above the surface of the desert and the tree itself bears only two true leaves that grow continuously in tattered strips from the stem.  As some Welwitschias have been Carbon 14 tested at over 1,000 years or more, the leaves must be that old as well.  These are but a few of the reasons why this tree may be the strangest vascular plant on Earth.

A poem so lovely as a tree?  Perhaps to eyes accustomed to noble crowns and mighty forests these desert dwellers may appear unlovely.  Yet as Katisha sagely - and poetically - said to Ko-Ko;

"There is beauty in the bellow of the blast,
There is grandeur in the growling of the gale,
There is eloquent outpouring
When the lion is a-roaring,
And the tiger is a-lashing of his tail!" - W. S. Gilbert, The Mikado

Comments

[GreenmanTim]

Thanks, Lene. I'd love to return, but my career and family life conspire to make that unlikely for the forseeable future. Maybe in a few years we can take a few weeks and visit old friends, but that would require a shift in finances. $15K-20 to get four of us there and rent a 4x4 isn't in the budget forecast!

[Lene]

Great post, as always, Tim. Thanks for linking from the WL mini-tree discussion. It's fun to see your personal pictures of these plants. What a harsh looking environment. Do you have any plans to return?

[Michelle]

Another Festival visitor here....thank you for a fascinating and informative post! Having moved from Central NY to the High Desert region of Central Oregon (all junipers and sagebrush), I have to admit that deserts do have their own sort of stark beauty.

[GreenmanTim]

I'm pleased you enjoyed it, Dave. Leafy and Cypress Spurge are indeed headaches, and can poison livestock as well as overwhelm habitats.

[Dave]

Here via the Festival of the Trees. Thanks for a very informative post. Your description of the venomous Euphorbia made me think of another Euphorbia, leafy spurge, which is such a troublesome invader in many parts of the U.S.