Welwitschia

 

The Welwitschia is a plant of remarkably bizarre habits and survives in very harsh localities where the annual rainfall is often less than 25 mm and where the coastal fog is equivalent to about further 50 mm. The Welwitschia's oldest living specimens are estimated at 1500 to 2000 years is capable of surviving severe conditions of stress.  The Welwitschia is considered to be a gymnosperm, although the relationship with other species in this class is not clear. The position of the Welwitschia in the hierarchy of the plant remains tenuous.


Leaf characteristics.

 

The leaves are the longest-lived in the plant kingdom, they are evergreen, a single pair and generally broad and flat. The broadest unbroken leaf is found in the Fläche measures 179 cm. This particular leaf was 6 meters long of which 3.15 meterswere living tissue. The surface that this leaf covers helps the plant to survive at a temperature on the soil as high as 65 'C. It keeps the soil under the plant cool and moist. The leaves grow annually an average 13.8 sm. Therefore the plant can produce up to 150 m of leaf tissue over a growth period of 1000 years. The leaves are on average 1.4 mm thick. The leaves that lay on the sand surface also prevent wind erosion.

Reproductive anomalies.

 

The female plant has large cones while the male plant has flowers. The male reproductive structure has six stamens each with an anther and a pistil. A female plant of average size may bear from 60 to 100 or even more cones. The Welwitschia female plant can produce a lot of seeds; up to 10 000 or even more. Unlike other known plants fertilization occur in the pollen tube rather than in the embryo sac. The seed units consist of a seed and a paper husk of winged segments. It is suggested that very strong wind would be required to successfully distribute the seeds. Most of the seeds that are shed have a very little chance of germinating.

Water absorption.

 

 Most plants absorb water from the soil through their roots. This water is then transported to the stem and the roots and the water is then lost through the stomata evaporation. The Welwitschia plant works the other way around. It is able to absorb water from fog through millions of stomata on the surface of its large leaves. From there the water moves to the rest of the plant.