By Ida K. Rigby for Let’s Talk Plants! April 2022.
We must begin with this column’s origin story. Our SDHS Book Club read Jonathan Drori’s Around the World in 80 Plants. One of the 80 plants was the Welwitschia, and I happened to mention during the discussion that I had seen it in Namibia. With even more than her usual enthusiasm, Karen England exclaimed that she wanted me to send her a photo. Fortunately, since our guide had taken us on a long detour just to see this plant, I had had the good sense to photograph it, but was unmoved. To my uninformed eye it was just a scrappy, unkempt heap. That’s the difference between a gardener (me) and a horticulturist (Karen). If you were lured into this article by the photograph, then you are a horticulturalist for sure.
A word about this new column.
As the title suggests, we will roam the globe rather randomly and encounter wondrously adapted plants, perhaps even an elephant or two, as we pass through, then return to places like Botswana, Morocco, Chile, Sardinia, Australia, Vietnam, Iceland and more to take a peek at some of their native plants, gardens and plant-related traditions. Just to give a sense of where we are, here’s a photo of the emergency fire equipment at the Damaraland airstrip, shovels and pails for sand.
So, now let’s take a second look at the bewitching Welwitschia mirabilis (marvelous) endemic to the barren, gravel soils of the Namib desert (southern Angola south through Namibia). The Austrian Friedrich Welwitsch encountered it in southern Angola in l859. He described staring at it “half in fear lest a touch should prove it a figment of the imagination” (Drori, p74).
It is now the national plant of Namibia. Actually, for all its squirrely growth, only two leaves grow from the rim of the woody center; they then split, curl and shred as over centuries as they are pommeled by the wind and nibbled by animals including antelope and rhinos. The Namib gets regular night fogs, which condense on the leaves that slope down toward the roots, which may, more than the deep tap root, be the source of water for the spreading, shallow roots. One Welwitschia near Swakpmund is over 1,500 years old. The seeds are windblown and wait for an unusually wet year to germinate. Some plants are male, some female. Darwin called it the “platypus of the plant world” in recognition of aspects that still remain controversial, including such mysteries as is it a Jurassic relic, the missing link between cone-bearing and flowering plants (gymnosperms and angiosperms)? For a discussion of this and other curious features of the Welwitschia see the website of the South African National Biodiversity Institute, Plantz Africa (pza.sanbi.org).
To illustrate the ecological diversity of Namibia I have included photos of a few other plants adapted to this harsh environment (northern Namibia includes the marshy flood plains of the Caprivi Strip, which we’ll visit in a column on the Okavango Delta in a few months). Most of the flora of Namibia has the same water conserving adaptations we see in our own arid southwest deserts: low, slow growth; hollow stems; waxy leaves; deep taproots; small leaves; narrow edges facing the sun to minimize heat absorption; and seeds that lie dormant until there is an adequate rainfall. Just the names of some plants, such as the thorny stemmed nara melon, Acanthosicyos horridus, which is actually a welcome source of water for desperate mammals during times of drought, testify to the shudders this desert evoked.
Similarly, the commonly called “venomous euphorbia,” Euphorbia virosa, which the San used to poison arrow tips suggests danger. (The San are the original inhabitants of Namibia and Southern Africa.) The Euphorbia avasmontana (below) is less toxic.
Namibia’s diverse habitats include the pans with seasonal pools; the most famous are the Etosha salt pans. The salty soil supports only a few grasses, so winds erode the desolate surface. Nearby to the east there are some mopane woodlands, and fan palms grow near waterholes; they produce hard “ivory” nuts that villagers turn into carved souvenirs for tourists. We’ll see southern African palms and mopane forests when we visit Botswana.
Damaraland is the inland desert between the Skeleton Coast and the Kalahari.
On its rocky hillsides you have to keep an eye out for puff adders (which blend in with the desert varnish of the rock piles — fortunately, a sharp-eyed companion kept my boot off one). Desert-adapted elephants, who can go for a few days without water, spend the winter in Damaraland’s sandy, dry riverbeds. These tree-lined corridors indicate underground rivers; the elephants follow the sparse forests above these rivers to village wells and water tanks. We were fortunate to meet a breeding herd as it closed in on a village. Children ran out to turn on the pumps so the elephants would not be frustrated. In these areas the most prevalent tree is the camel thorn, Acacia erioloba, which is browse for elephants, and in more open areas it supports sociable weaver condos. Ebony, leadwood and tamarisk trees also line these dry riverbeds.
Other habitats include gravel plains supporting dry grasses and savanna with various acacias, teak and scrubby shrubs. The Vlei are low dips, which are seasonally moist and produce ephemeral grasses.
Isolated, white trunked shepherd’s trees, Boscia albitrunca, grow in the sandy soil and afford precious shade for shepherds and other mammals. The trees’ flat line reflects the height that antelopes nibble their leaves.
The spectacular dunes at Sossusvlei feature a few camel thorn where there is underground water; they are often overtaken by the towering dunes. At Dead Vlei there are dead, 500 year old acacias frozen in time in an area of a river long ago deserted.
Our next few bi-monthly columns will feature habitats of other areas in southern Africa.