If you plan to tour the northern regions of Namibia
first you will see Welwitschia plants in Damaraland and at the
Petrified Forest. However, these are small samples of this unusual
plant when compared to the Welwitschia that you can see on the
'Welwitschia Plains" some 70km inland from Swakopmund. They're well
worth the visit.
Welwitschia mirabilis: Several of the world's leading botanical gardens
display examples of the Welwitschia mirabilis. However, only when viewed
in its' natural environment can any desert plant be fully appreciated.
The South Namib Desert is a sand sea of dunes that
runs 700km from the Orange River to the Kuiseb River. Apart from the 4km wide
belt of Coastal Dunes between Swakopmund and Walvis Bay, The Namib north of the Kuiseb River is a Gravel Plains Desert.
The plant is only found naturally in the Northern coastal belt of the
Namib Desert and the largest specimens are found about 70km inland from Swakopmund.
Along the trail you will see examples of male and
female plants surrounded by neat rock circles and marked for easy
identification.
The local natives called the plant n'tumbo, and in times
of hardship it could be used as a food source. The desert elephant,
Oryx, rhinoceros, springbok and zebra have been know to eat it. A
variety of
insects also use the plant for sustenance and shelter under it's leaves.
The 'Discoverers' : The
plant is named after the Austrian botanist Dr. Friedrich Welwitsch
(1806-1872) who first 'discovered' the plant near Mocamedes in
South-West Angola in 1860 while working for the Portuguese Government.
On completion of his contract he took up residence in London, England.
The Africa explorer painter Thomas Baines trekked
through Namibia in 1861 and made sketches of the plant which were later sent
to London. The plant was first named Tumboa bainesi. Baines wrote of
his first sighting of the plant being in one of the sandy ravines
running into the Swakop River.
"In its sandy bed we came upon a bulbous
plant with four leaves, fourteen or sixteen inches wide, and, when
perfect, nine or ten feet long, lying in a cross upon the ground. The
ends were withered and curled up, and in the centre was an assemblage of
small stems six inches long, each bearing on smaller stems from three to
five greenish-crimson substances, of an elongated ova three inches long
and three quarters of an inch thick, and marked with scales like a fur
cone. On this plant I found a number of red, or red and yellow field
bugs, and captured some of them for preservation, beside making an
outline of the plant itself, intending to colour it from some of the
specimens we expected to see to-morrow."
The
priority of Dr. Welwitsch was eventually recognized and the plant given
the name Welwitschia mirabilis.
The Welwitschia mirabilis is a unique and
protected plant (CITES Appendix ll): that still invites a
considerable amount of research. The plant only grows two leaves during
its entire lifetime. The bunches of leaves seen on older plants are
actually splits of the original leaf pair. Apart from Cacti and
succulents most desert plants are xeromorphic having spiny leaves with a
small surface area. However the Welwitschia has long, wide and
relatively thin leaves, similar to plants found in climates that experience regular rains. The Welwitschia leaves
have up to 22,000 stomata (small pores) per sq cm combined on both upper
and lower leaf surface which are used for the exchange of gases in the
photosynthesis. In contrast to other leafed plants
these stomata remain opened during foggy or wet conditions and absorb
moisture. When hot conditions are being experienced these stomata close
to reduce the evaporation of plant fluids. The root system reaches
depths of 2 to 3 meters and can grow laterally as much as 30 meters
across.
Water
Intake: Rainfall in the Namib is limited and ranges from 20mm in the
coastal belt to 120mm further inland, per year. Moisture from the early
morning fogs produced by the cold Benguela (sea) Current for about 300
days per year add about another 50mm of moisture per year.
Temperatures experienced in the Namib can fall to near
freezing point on a cold winters night. Daytime temperatures of the gravel
surface can reach 70 Celsius, and the Welwitschia leaf ends spilt and become
burnt.
