大象传媒

The Namib is hotter and drier than the Kalahari. Very few plants can survive here. The huge Welwitschia plant, however, does grow here and nowhere else. It is named after Dr Welwitsch, an Austrian botanist who came to the Kalahari in the 1800s. Welwitschia have male and female plants. The females have cones like fir trees, while the male has growths like stamens that produce pollen. So Welwitschia seem to be a missing link between coniferous trees and true flowering plants. But the oddest thing about it is perhaps its leaves, which grow very slowly from the top of its central trunk. A leaf could be 400 yards long on a plant that is thought to be 1,500 years old. It is the Welwitschia's leaves that enable it to collect moisture, thanks to the dawn fogs that roll in from the Atlantic. As they swirl around the plant, moisture condenses on the plant's huge leaves. Some droplets are then absorbed through small cracks on the leaves' skin while the rest of the water is channelled to the ground where it is sucked up by roots just below the surface of the sand. The fog also provides water for darkling beetles which climb to the top of the dunes on foggy mornings, and collect moisture on their limbs which they then tip into their mouths.