Welwitschia mirabilis (Tree Tumbo)
Wonderful, weird, strange, bizarre, fascinating, and unique are the words used to describe Welwitschia mirabilis. It has only two opposite…
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The second-last in the plants and biomes of South Africa series is featured today. Taisha writes:
Today, we take a slight detour from South Africa, as this species is not present in the country. Welwitschia is found only in the Namib Desert of Namibia. However, the Namib Desert slightly extends into South Africa where it forms the country's sole area of desert biome. The Namib Desert is one of the smallest and oldest deserts in the world. I chose Welwitschia as it has not been featured on Botany Photo of the Day before and it was not easy to find a plant species in the Botany Photo of the Day Flickr Pool to represent this biome. Still, this species is an interesting representative for the desert. Daniel contributed these photographs of Welwitschia mirabilis from Huntington Botanical Garden.
As implied above, the desert biome occurs in only a small part of northwestern South Africa, primarily the Springbokvlakte area of the Richtersveld. The altitude is between 600 and 1600 m, which results in a slightly cooler climate than other true deserts (though it remains more climatically extreme than the succulent Karoo and the Nama-Karoo biomes). Temperatures can be hot, up to 45°C. Similarly extreme, temperatures can drop over 20°C from day to night. Winter temperatures can be as low as -12°C. Fog from the nearby Atlantic Ocean accounts for much of the precipitation, although there is some variable summer rainfall (
10-80mm annually). True deserts are largely sandy with low organic material in their soils.
The vegetation within the desert biome is typically annual grasses and other plants. After a season with rarely abundant rains, short annual grasses may grow, whereas in most years the annual plants persist as seeds. Some perennials may survive, particularly in areas associated with local concentrations of water.
Welwitschia mirabilis is a monotypic species of the Welwitschiaceae under the plant Division Gnetophyta--a small group of seed plants that have intermediate characteristics between gymnosperms and angiosperms. The oldest specimens of Welwitschia in the Namib Desert are thought to be more than 1500 years old, and recent fossil evidence suggest that Welwitschia was present during the Cretaceous (
112 million years ago). Some photos of the plant in habitat are available via Wikimedia Commons: the biggest known plant and a couple plants in the landscape.
This dioecious (male and female individual plants male and female cones are shown above) evergreen species has a woody unbranched stem that is shaped like an inverted cone. The stem is surrounded by a bi-lobed crown of green photosynthetic tissue. There are only two opposite, persistent, ribbon-like leaves that grow continuously from a basal meristem and die off at their tips over time. Unique among all extant plant species, after the first two leaves form, the terminal bud dies and the apical meristematic activity is transferred to the periphery and base of the leaves. In other words, it has ever-growing persistent leaves, with the leaf ends being the oldest part of the leaf.
Plants→Welwitschia→Wonderplant (Welwitschia mirabilis)
|Plant Habit:||Herb/Forb |
|Life cycle:||Perennial |
|Sun Requirements:||Full Sun |
|Plant Height :||12 inches to 18 inches|
|Leaves:||Other: Plant contains only 2 leaves that lie on the ground |
|Bloom Size:||Under 1" |
|Underground structures:||Taproot |
|Suitable Locations:||Xeriscapic |
|Resistances:||Humidity tolerant |
|Propagation: Seeds:||Provide light |
|Containers:||Needs excellent drainage in pots |
While this plant grows in the desert, it is a coastal desert and the plant is not actually succulent, ie. it does not store water. It will die quickly if it completely dries out. So while it can be suitable for xeriscape, it needs a reliable source of water. In its native habitat the taproot grows to tap into deeply located water sources while it develops a network of shallow roots that capture moisture from fog/mist derived from the nearby ocean. This shallow network is usually not observed in plants grown in pots or out of habitat.
This plant can live over a thousand years in its inhospitable desert habitat (Namib desert of S W Africa - Angola). It is the only member of its plant family. Truly a 1 of a kind plant. It is composed of 2 leaves, a stem base, and a tap root. It only grows these 2 leaves in its entire lifetime. Described by MOBOT as 'weirdest terrestrial organism' in the world. KEW calls it 'one of the world's ugliest plants.' Considered 'near threatened' due to infection potential from a fungal source. Eco-tourists flock to its home environment to observe.
Welwitschia Species, Wonderplant
Tropicals and Tender Perennials
Drought-tolerant suitable for xeriscaping
USDA Zone 9b: to -3.8 °C (25 °F)
USDA Zone 10a: to -1.1 °C (30 °F)
USDA Zone 10b: to 1.7 °C (35 °F)
USDA Zone 11: above 4.5 °C (40 °F)
Where to Grow:
Soil pH requirements:
From seed direct sow after last frost
This plant is said to grow outdoors in the following regions:
On Jun 5, 2016, poeciliopsis from Phoenix, AZ wrote:
Central Phoenix -- I was so delighted to find this plant at Plants for the Southwest (aka Living Stones Nursery) in Tucson in October 2014. It has been growing happily in my yard in a pot -- or perhaps "growing" is not the right word, since it has the same two leaves it had when I bought it. But those two leaves look just fine. I water it about once a week and every other week it gets a good soak from flood irrigation. It gets mostly filtered shade, with some direct sun late in the afternoon.
On Nov 11, 2005, BayAreaTropics from Hayward, CA wrote:
Despite the image this plant conjures up-the dry deserts,great drought tolerence for ages. It actually requires regular watering as a potted plant.In fact, let a seedling become "cactus dry" just once, and like some tree ferns, it croaks! And the local botanical garden has large ones in a greenhouse that is decidedly non tropical in winter.Tricky to maintain.
And to grow from photo three size to photo two size takes 10-15 years.
On Jan 30, 2004, palmbob from Acton, CA (Zone 8b) wrote:
This is one of the weirder plants you can get for a warm, dry xeriscape garden. It is a native on Nambia and lives in open, sandy desert often as the only plant around for miles. It is a very low growing 'thing' with only two leaves that continue to grow for centuries, slowly creating a pile of twisted, long, thick, leathery dull green strap-like leaves. In cultivation it is a curiosity only- not a very attractive plant. But old plants are worth a fortune. I have only seen this plant available more commonly for sale in the last 5 years. You can only get dinky ones and it is a plant you need to put in your will so your grandchildren can brag about it. It's unique and the only plant in its family.
On Aug 11, 2003, Monocromatico from Rio de Janeiro,
Brazil (Zone 11) wrote:
This is a bizarre short plant from the semi-deserts of southern Africa. It has a short woody stem that grows very slowly. On the top of the stem (looks like a disk) there are two leaves. Those are the only leaves the plant will have for its whole life (that can be rather long, by the way). Those leaves are very long, reaching up to 2,5m long, taking decades to reach that lenght. The tips often get teared, spliting the leaves in many stripes that can make one think it has many leaves. As a Gymnosperm, it produces small reddish-brown cones.
It comes from the desert, so make sure you have a sandy/rocky soil, little water and full sun. Protect it from shocks and from the wind if you want the leaves to be intact.