Images of Dry Tropical Habitat: Welwitschia sp. from Namibia

Images of Dry Tropical Habitat:
Welwitschia sp. from Namibia

The plant Welwitschia mirabilis gets my vote for the weirdest terrestrial organism. Science fiction has never come up with any Martian to rival this plant. It has a low trunk and two leaves that sprawl on the Namib gravel for the entire life of the plant, which can span many hundreds of years. If this weren't enough, Welwitschia is a gymnosperm related to Mormon Tea (Ephedra) and produces seeds in cones, not from flowers. An individual Welwitschia plant produces either male or female cones, but never both.

All of these photographs were taken in the Namib- Naukluft Park in the western part of central Namibia, which is the easiest place to see them in the wild. This area is close to the southern limit of Welwitschia's distribution, which reaches as far north as southwestern Angola.

Click on a thumbnail for a larger image:

Habit photographs

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1. - 6. The basic body plan of Welwitschia of a low trunk with two lobes and two leaves often becomes confounded in old plants, as in 1., 3. and 4. In others, it seems easier to recognize each lobe and its leaf, as in 2., 5., 6., and 7.
7. A very large female plant. The stalks covering the top of the trunk are from the seed cones.
8. The underside of a Welwitschia leaf provides a lot of shade and is thought to moderate its immediate microclimate.

Habitat photographs

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9. - 15. Welwitschia occurs in a variety of habitats in the same general area, including open flats, rocky canyon walls, shallow drainages, and alluvial fans. In some areas, they are the most conspicuous element of the vegetation for most of the year.

Reproductive structures

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16. Young female cones
17. Older female cones with Welwitschia bugs on them (see below).
18. The center of a female Welwitschia cone is a light, woody spindle- shaped structure, shown on the right. It is surrounded by tightly packed ranks of shiny scales, on the left, each one with a winged seed sitting atop it.
19. Male cones with pollen- bearing structures visible as the yellow bunches near the middle of each cone.

Associated fauna

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20. Welwitschia bug Probergrothius sexpunctatis (I think), an insect that feeds on Welwitschia sap.