The second Latin word in the official name of this plant means admirable, marvellous. Which definitely is pertinent. I would add weird. Friedrich Welwitsch was an Austrian doctor and botanist who first described the plant in 1859.
This so-called living fossil thrives under a harsh — to say the least — climate, that of the Namib desert, in-between Namibia and Angola. This area, 80 to 130 km wide (50-80 mi), stretches 1,500 km (1,000 mi) along the west coast. It comprises 15 per cent of the total land area of southwest Africa. Rainfall is less than 100 mm (4 in) during the wet season, February to April.
Which raises the life-or-death question for a plant — truly, survival or extinction for the species, access to water. In the Namib desert, with very occasional and sparse rain, fog is the best water source. Welwitschia is remarkable, even at first sight, for its huge and permanent leaves. These two leaves can grow up to about 4 m (13 ft) in length and they endure throughout the lifetime of the plant. Furthermore, in like manner to giant sequoias, Welwitschia can reach an age of 2,000 years! This foliage, of course, does not
stay intact, it is often lacerated by strong winds. But this hardy plant regenerates quickly and impressively any of its torn leaves. They are major survival assets of the plant, collecting on their very large surface humidity from fog. These leaves indeed possess millions of stomata or minute epidermal pores on both the upper and lower surfaces, about 22,000 per square cm (142,000 per square in). Another asset for water collection is the taproot that digs into the ground in search of water, sometimes reaching 30 m (100 ft) in depth.
Welwitschia requires high humidity from fog for a positive carbon balance. It may survive a drought for as long as 150 days — possibly much longer. It is a so-called CAM or C4 plant, for the metabolic pathway it uses in photosynthesis. This metabolic pathway enables carbon dioxide absorption during the night, and then photosynthesis with closed stomata during the day. Obviously, this increases plant water use efficiency. Welwitschia shares this mode of CO2 assimilation with cacti and other desert succulents.
Like conifers, Welwitschia — the only surviving member of its family — belongs to Gymnosperms.
How old is this species? About 110 million years (ma). How do we know? From fossils. The most noteworthy finds are from the lower Cretaceous (Aptian, ca. 112-114 ma) Crato Formation of northeast Brazil. Fortunately, this fossil is rather complete, consisting of young stems with a]ached cotyledons, isolated leaves, and axils bearing male cones. Moreover, it was securely identified as a Welwitschia by its unique kind of leaf venation.
That Welwitschia lives such a challenging life in the bleak environment of the Namib desert and not elsewhere is a tribute to its fortitude!