These peculiar little plants occur in the northwest corner of the Richtersveld (Oranjemund to Koekenaap), where they form rather dense mats.
They have tuberous roots and tough and fibrous aerial stems, which are more or less terete, 30-100 mm long and 2-5 mm in diameter. The stems do not stick out more than a few cm above ground, as a result of the continuously blowing sand-blasting winds; they are protected by a thick leathery skin.
The flowers appear from April through September and are usually yellow-green (Williamson in his Richtersveld book gives the colour as mainly chocolate to orange-brown).
Widespread from Ceres in the southwestern Cape to Albany in the Eastern Cape, this species is often a dominant feature of the landscape in the Little Karoo and southern parts of the Great Karoo. This is especially the case in the dry season, when the plants look distinctly reddish.
Usually the rosettes are single, but sometimes they form small groups; they are short-stemmed or (in old plants) with a stem up to half a meter long.
The leaves are long (about 30 cm) and rather narrow (about 6 cm at base), most of the time reddish-green -but see above. The name microstigma (very small spot) refers to the numerous white spots that are usually present on both sides of the leaves. The margins are armed with sharp teeth.
The inflorescences are up to 1 m tall, normally 2-3 per rosette, always undivided.
In most cases the flowers are bicoloured in red and yellow, being dull red in bud and turning yellow on opening ; sometimes they have only one colour, either red or yellow. They appear mainly from May to July.
One of the many older names for this plant is Mesembryanthemum cigarettiferum.
Gustav Schwantes in his magnum opus “Flowering stones and Midday-Flowers” (1957) gives a wonderful description of the species, referring to that name as follows:
“…It was a small, tufted, branched plant, on which were a number of cylindrical structures with dry skins like paper bags; from each of them projected the tip of a pair of leaves at rest within. These paper bags were formed by the drying up of earlier leaf pairs which had been joined for a long way up. The young pair of leaves inside them was. however, much more deeply divided. The surrounding bags reminded Berger so strongly of the paper mouthpiece of a cigarette that he gave it the very descriptive name of Mesembryanthemum cigarettiferum, the Mesembryanthemum bearing cigarettes. The leaves at rest within the bags, when the plants had been potted up and started into growth, grew out of the bags and developed into thick, narrow leaves such as are often found in the Mesembryanthemaceae and produced from the centre an equally narrow pair of leaves, which, however, were joined for a considerable distance so that only the extreme ends of the leaves appeared as free tips. Within this pair of leaves, which looks like a cylinder with little horns at the top, the young, but deeply divided, pair develops; it draws on the pair surrounding it so that this finally becomes the protecting skin, the paper bags referred to above. Clearly this is a case of one of the many interesting contrivances for protecting the young growth from the rigors of the dry period. This protection is achieved here in the same way as in Ruschia pygmaea (see picture #2, FN) and many other species of Mesembryanthemaceae.”
The plants form compact clumps with many branches, up to 20 cm in diameter, with
light blue-grey to green-grey leaves.
The flowers appear from July to October and are about 4.5 cm in diameter; they open in the early afternoon.
Widespread on shale slopes and flats at an altitude of 300-950m from Namaqualand to the western Little Karoo and the only Cheiridopsis that occurs this far south.
Pictures taken near Matjiesfontein on the following dates:
#1 31 Jan. 2009
#2 18 Feb. 2007
#3 and #4 17 May 2008
Subspecies namaquensis differs from its sibling by having no more than two leaves, one of which is usually inconspicuous.
The inflorescence is shorter (5-10 cm tall) and always single and the filaments have a double tuft of hairs.
These plants occur only in the Northern Cape, from Springbok to the Richtersveld in gravelly places.
One often comes across the name of the species as Bulbine mesembryanthemoides, but because Haworth used the spelling mesembryanthoides in his original description, this has to be accepted as correct.
Subspecies mesembryanthoides has a small underground tuber and usually 1-2
leaves (rarely up to 4). The leaves are cylindrical, 1-2.5 cm tall and up to 2 cm in diameter. As soon as the dry summer period arrives, they start to whither.
Flowers appear in spring and summer (Augustus-November), usually after the leaves have retracted. Each plant may have 1-3 inflorescences up to 20 cm tall.
This subspecies occurs widespread from the Knersvlakte in southern Namaqualand to Graaff-Reinet in the Eastern Cape on rocky slopes and flats.
If there were a list of favourite types of succulents, I’m sure the so-called window plants would rank very high. Most of these plants belong to the Aizoaceae (Mesembs), but they are also found in Bulbine and Haworthia.
When one looks up information on window leaves, one gets the impression they are all built on the same principle: the surface of the leaf tip lacks chlorophyll, the central parenchyma* reaches up to the epidermis and as a result of this combination, the leaf tip looks and acts like a window.
In a few cases however, the windows are formed differently.
It has taken me quite a while to find a place where this is described in a comprehensive as well as comprehensible way.
In Cactus & Succulent Journal (US) vol. 16, 1974, Werner Rauh published an article called Window-leaved succulents. He starts his explanation with a description of Haworthia obtusa (=cooperi) var. pilifera and uses more or less the following wording:
“The numerous fleshy leaves are nearly hidden in the substratum and we can only see the transparent, glass-like leaf tips, ending in a long hair. The transparence of the leaf tips is caused by a lack of chloroplasts**. We find the assimilation parenchyma only in the lower two thirds of the blades, but these leaf parts are not accessible to the light. The consequence of this anatomical structure is that light, necessary for assimilation, can reach the assimilation parenchyma only by passing the transparent windows. But the leaves of H. pilifera are not in the morphological sense true window leaves.”
He then moves on to Haworthia obtusa (=cooperi) var. dielsiana, saying:
” … the most remarkable feature is the behaviour of the leaves in the course of their development: young leaves are of the same shape as those of H. pilifera, but becoming older, the upper third of the lamina, which exceeds the soil surface, dies off, so that only the water parenchyma, covered by the shrunken epidermis is to be seen. The lower parts of the leaves with the assimilation parenchyma are hidden in the ground; sunlight can reach it only by passing through the water parenchyma.”
This is the same type of window formation we find in Bulbine mesembryanthoides. In Rauh’s words:
“Becoming older, the upper parts of the leaves die off, as in Haw. obtusa var. dielsiana and the result is the formation of a big window with a plane surface. The assimilating parenchyma is completely hidden in the substratum.”
We know that strong sunlight destroys the chlorophyll, which is essential for the plant’s metabolism. Window-leaved plants are hidden in the ground (at least in the hot and dry season) and sunlight can reach the assimilation tissue only through the windows, passing through the water parenchyma. This filtering process protects the plants against very strong light.
In experiments carried out with Fenestraria, it was found that the light is reduced so much that the chloroplasts will not be damaged, but stays strong enough to allow sufficient assimilation and production of organic substance.
* parenchyma is the relatively undifferentiated tissue that makes up the bulk of many plant organs and is often used for storing of water or food.
** chloroplasts are the tiny parts within plant cells that contains chlorophyll.
This is what the plants look like when the tips of the leaves start dying down.At the end of the process the plants look like this.
