Thursday, June 25, 2015

South Africa 8. Succulent Paradise

Euphorbia stellospina remarkably mimics the
growth form of cacti native to the Americas.  One
cllue is the forked spines found only in Euphorbia.
Northward and inward from South Africa's west coast, it becomes increasingly arid. These southern African deserts are home to the greatest collection of succulent plants on the Earth.  Succulents are plants that store large quantities of water in their soft tissues, allowing them to remain active during prolonged dry seasons.  Other desert plants become dormant, fulfilling their life cycles during the brief period after a rainstorm, or have other specialized means of survival, such as long taproots that reach underground water supplies.

One first thinks of cacti when the word succulent comes up, and they are almost completely confined to the Americas.  None occur in southern Africa.  With some 1500 species of cacti, one might think the Americas would have the greatest collection of succulents.  We can add to their numbers some 200 species of Agave and many members of the Crassulaceae, but in Africa, the role of succulent is filled with members of an even greater variety of families.

Hoodia rushii (Asclepiadaceae) is a cactus-like
member of the stapeliad group. This is the genus
from which a controversial appetite-suppressant
is obtained. [Note: the Asclepiadaceae is combined 
with the Apocynaceae in some systems.]
One can categorize most succulents as either stem succulents (cactus-like) or leaf succulents (like Agave or Sedum). The most numerous stem succulents in Africa are in the genus Euphorbia  and the stapeliad group of the Milkweed family (Asclepiadaceae) or ), but there are also some in the Apocynaceae Pachypodium), Asteraceae, Grape, and most improbably, the Passion flower (Adenia) and Geranium (Pelargonium) families, as well. African leaf succulents include many in the Crassulaceae, the genus Aloe and its relatives, and the ice plant family, Aizoaceae.
Pachypodium namaquensis (Apocynaceae) is
related to Nerium oleander, periwinkle, and
confederate jasmine..

It's hard to put a number to this collection, but I believe it exceeds the number of succulents in the new world.  For example, the stapeliads consist of 29 genera, each with a number of species. The genus Stapelia alone has 55 species.  Euphorbia consists of over 2000 species worldwide, and includes tiny herbs, trees, and about 1000 cactus-like succulents in Africa.  The genus Aloe, all succulent and mostly native to Africa consist of  500 species, the Crassulaceae contains several hundred here, and so the number builds up.  Aizoaceae, a family with succulent leaves contains 1782 species in Africa.

So I rest my case for southern Africa possessing the greatest treasure chest of succulents, and invite you to enjoy the pictures.
Pelargonium spinosum is a spiny, succulent
 member of the large genus featured earlier in this

This Agyroderma (Aizoaceae), like the related genus Lithops,
typically maintain only two functional leaves that are half-
buried in the rocky soil, and have the common name of
living stones. 

A stop at the Kokerboom Nursery, gave us a great preview of
the native succulents of South Africa.
Tylecodon paniculatus (Crassulaceae) is a
common desert shrub in southern Africa.
The attractive blossoms of Tylecodon paniculatus.
This planter box features living stones and other members
of the Aizoaceae.

Euphorbia mauritanica has slender succulent stems, and
leaves during the rainy season.

Euphorbia tuberculata; one of many cactus-like
species in this genus.

Orbea ciliata is a cactus-like member of the stapeliad
group of the Asclepiadaceae.

Sarcocaulon crassicaule is a succulent member of the Geraniaceae.
Aloe erinacea; a small, spiny member of
this large African genus.

Larryleachia cactiformis, a stapeliad with small, dark flowers.
Aloe pitchifolia at the Kokerboom Nursery.

Aloe framesii

Aloe chabaudii

Trichocaulon flavum, another stapeliad; note the milkweed-like
follicles on the stem on the right.

Eupohrbia clandetina; another succulent with
temporary leaves.

Wild Aloe dichotoma trees on a rocky hillside.

The bark of Aloe dichotoma forms patches of different color.

Thursday, June 18, 2015

South Africa 7. Up the west coast

The lush landscape north of Cape Town features farms isolated 
amidst hills covered with native fynbos (equivalent of our
As one ventures up the west coast of South Africa from Cape Town, the hamlets and farms become sparser, and the landscape becomes wilder and drier.  At the beginning, we are in the lush fynbos similar to what we've seen elsewhere.  Spring wildflowers are everywhere, as are the wildflower shows and exhibits.  South Africans do love their native flora, and one sees more natives than exotics in their landscapes and gardens.

Visitors examine a display of local wildflowers at the 1998
Darling Wildflower show.

On my excursion with 1998 Botanical Garden Congress, our first stop was the spring wildflower show, held each September in the small town of Darling north of Cape Town.  The show serves as an excellent introduction to the local native wild flowers. In the exhibit hall specimens were lined on tables and labeled - everything from ground orchids to the weird saprophytes in the genus Hyobanche.

Labeled wild flowers create a living field guide.
Satyrium erectum is one of many native ground

Thoroughly labeled and interpreted displays make the Darling Wild Flower
Show a truly educational experience.

Wildflowers are not the only attraction in South Africa.  North of Cape Town
we encountered this massive colony of gannets, along with penguins and other
marine birds. 
Further up the road we came to the Clanwilliam Wildflower Garden - another fabulous stop and opportunity to learn about local wildflowers. Especially exciting was our first glimpse here of the giant Aloe dichotoma.

At Clanwilliam, a carpet of wildflowers tumbles down a hill, watched over by
giant tree-like Aloe dichotoma.  Aloes are monocots, and incapable of making layers
of wood like other trees, but they have evolved another way of increasing their
thickness and strength, by adding new fibrous vascular bundles and parenchyma
tissue around the periphery of their stems.
North of Clanwilliam, we entered the region known as Namaqualand.  We continued to see new wildflowers in this increasingly dry region, but also had the chance to visit some caves containing 10,00 year-old paintings by the native San people.

Please enjoy the pictures, which will explain themselves.
Babiana angustifolia (Iridaceae) provides splashes
of violet close to the ground.

Bright red blossoms of Cotyledon orbiculata 
(Crassulaceae) form living, nectar-filled  bird-feeders 
at Clanwilliam.

A multi-colored Sparaxis, either S. variegata or
S. villosa (Iridaceae), at Clanwilliam.

An attractive member of the genus Polygala

A yellow-flowered species of the genus Lampranthus (Aizoaceae), might
be mistaken at first glance for a member of the sunflower family,
but these are true, single flowers.

Cyanella hyacinthoides (Tecophilaeaceae)

Lapeirousia anceps (Iridaceae) appears to mimic some species
of Pelargonium.

A red-flowered Lampranthus (Aizoaceae) joins forces with a piece of driftwood
to form a natural work of art.

The dainty blossoms of Nemesia ligulata (Scrophulariaceae) dance above red
Lampranthus blossoms.

Diascia longicornis (Scrophulariaceae) has
long spurs that are filled, not with
nectar, but with a nutritious oil collected
by pollinating bees.

An orange-flowered Cotyledon orbiculata
Monopsis simplex (Campanulaceae) straggles along the ground.

A Namaqualand landscape of drought-tolerant 
shrubs line the path  to an ancient art gallery (entrance
 in rocks ahead).

An anonymous San artist depicted ancient archers on the hunt.  The image appears to overlay an earlier work.

Another painting depicts a herd of giraffes.

Anisodontea triloba, a member of the Hibiscus Family (Malvaceae)

Herrea elongata is a member of the succulent family,

Hyobanche sanquinea (Orobanchaceae) does not photosynthesize.
Instead, it draws its nutrition through a symbiotic fungus that
parasitizes tree roots.

Romulea flava (Iridaceae) is a geophyte, emerging
from a corm in the spring. It will disappear again
 after producing seeds.

Anchusa capensis (Boraginaceae) adds a swatch of
bright blue to the Namaqualand landscape.

A species of Lachenalia (Asparagaceae). 

Salvia africana-coerulea (Lamiaceae) is related to mints,
sage, and catnip.

Asparagus lignosus (Asparagaceae).

Babiana curviscapa (Iridaceae) near Leliefontein.
A colony of Arctotis fastuosa (Asteraceae) drapes the edge of a ravine.