Welwitschia mirabilis – A living fossil
This strange and rare plant is a native of southern Africa, where it occurs in
the Namib Desert. It consists of a short, thick trunk, which tapers below ground
to a long taproot. That’s why they’re planted here in water pipes rather than
normal pots. Above ground, they’re remarkable for their two leathery, ribbon-like
leaves. These leaves are constantly growing at the base, while their ends dry out
and fray. Amazingly, these are the only two leaves the plant will have in its entire
life – and this plant can live for centuries! The oldest known example is somewhere
between 1,500 and 2,000 years old.
Welwitschia is a living fossil. The nearest relatives of this ancient plant died out long ago in the mid-Cretaceous about 110 million years ago. A fossil seedling of one of these relatives has been found in Brazil; the fossil was recognized as a Welwitschia by its unique kind of leaf venation. As its seeds are not enclosed by a carpel, Welwitschia is classified as a gymnosperm, a group also including modern conifers like pines and firs.
Welwitschia is considered a “living dead”, surviving for centuries in the parched Namib desert. They are highly adapted to the harsh environmental conditions, with tap roots that – barely – reach the water table. Only those generations of seedlings are thought to survive, which germinate during periods of higher rain fall. It is unclear how much longer Welwitschia will survive, given the Earth’s warming climate.