A Strange Gymnosperm From Africa

What you are looking at here is not just a pile of discarded leaves. It is indeed a living plant. Would you believe me if I told you that it is a distant relative of pines, spruces, larches and firs? It's true! This right here is Welwitschia mirabilis, a representative of an ancient lineage of gymnosperm!

Welwitschia is endemic to the Namib Desert of Africa. It is hard to picture any plant living in such a dry area. In some years it never even rains. Welwitschia persists despite this fact. It tends to grow in watercourses and outcrops, thus enabling it to gather what precious little rain does fall. It has a deep taproot suggesting that it relies heavily on ground water. The leaves of Welwitschia also have high amounts of stomata on both surfaces enabling it to absorb water directly from the fog that regularly blows through when colder air currents mix with hot air from the desert.

For a long time it was believed that Welwitschia represented true neoteny, which is the retention of juvenile characteristics into adulthood. It was thought that Welwitschia was nothing more than a sexually mature seedling with exaggerated cotyledons. This idea was later abandoned when Martens showed that Welwitschia do develop further than the seedling stage. What really happens is the apical bud, which is responsible for vertical growth in plants, dies quite early on in development. In essence, Welwitschia has lost its "head."

I was not kidding when I said that Welwitschia is a gymnosperm. Once sexual maturity is reached, cones are produced. Individual plants are either male or female and unlike many of its relatives, Welwitschia is not wind pollenated. Instead it relies on insects to transfer pollen from male cones to female cones.

Probably the most remarkable aspect of Welwitschia ecology is its longevity. Individual plants can live well over 1000 years. Some individuals are estimated at around 2000 years old! In such a harsh desert environment, persistence is the key to survival for Welwitschia.

Photo Credit: Petr Kosina

Further Reading:
http://www.jstor.org/discover/10.2307/2442386…

http://www.plantzafrica.com/plantwxyz/welwitschia.htm