The survival of the fattest: Introduction

A photograph of Lithops olivacea in the wild, for comparison with the drawing below of the same species in cultivation.

The drawings above, were in the first book on succulents I ever saw. They showed plants apparently called “living stones” and made such an impression on me that over sixty years later, I still know exactly how and where I came across them. Because they looked so peculiar, at first I thought they were figments of the artist’s imagination, but I soon found out that plants like these really existed and this was the start of a lifelong fascination.
From the beginning, one of the most intriguing aspects of succulents to me has been the way in which they manage to survive in the most difficult situations. Over time I visited many countries to look for succulents in their natural habitats and this only added to that feeling of wonder.
In 2001, my wife and I moved to South Africa, which gave me more time and opportunity to see and photograph succulents on their home turf.
Some years later, I was asked by one of the local garden clubs to give a talk on succulent plants. Over the years, I had often done this in the Netherlands and neighbouring countries, but this was the first time I was asked to do so in South Africa. I quickly realised that the invitation was both a challenge and an opportunity to give a completely different talk from the ones I was used to give. When I thought about why exactly I was so intrigued by these plants, I was automatically taken back to my first encounter with them. At first it was their peculiar and often even bizarre appearance that was so appealing. As I came to know more about them, I found out that this was in fact the result of a long process in which they developed adaptations to the conditions they have to cope with in their homelands.
I decided to make this the subject of my talk and called it “The survival of the fattest” (with apologies to Charles Darwin).
As the series of posts of which this is the first instalment, is based on and inspired by that talk, it seemed fitting to give it the same title.
Because succulents show such a bewildering variety in adaptations, it is not easy to recognise and understand the common elements. I have tried to arrange the material in this series of posts in such a way that at least some order is created out of chaos.
There is always more than one way to tell a story and the author has to choose which way to take. Each choice excludes a number of other possible ones. I can only hope that the choices I have made here do justice to the subject as well as appeal to the reader.
The main purpose of the pictures in these posts is to show what beauty can result from adversity; the text is meant to explain the mechanisms behind it all in understandable language. As I have lived in South Africa for a long time now and most of my pictures have been made there, it seemed logical and practical to approach the subject mainly from a South African perspective. This also makes sense because the dry parts of Southern Africa are among the richest succulent areas in the world; about half of all succulents occur here.

Other posts in this series:

What are succulents, actually?

Where  do succulents grow?

Problems and solutions, part 1

Problems and solutions, part 2

Collecting water

Storing water

Senecio crassissimus

Because of the peculiar orientation of its leaves, this species is often called Vertical Leaf Senecio or propeller plant.
The plants have creeping to erect stems, to 80 cm tall  and much-branched.
The vertically flattened leaves* are variable in shape, size and colour, to 10 cm long, 3 cm wide and 3-5 mm thick.
Inflorescences are to a meter tall.

The species is widespread in central and southern Madagascar, where it grows on denuded granite rocks, often together with members of the Euphorbia milii groep, such as E. horombensis and E. fianarantsoae and Pachypodium species (first picture shows P. horombense in foreground).

*  This vertical compression of the leaves is usually regarded as an adaptation which reduces the amount of light that reaches the leaf surface, resulting in lower daily water loss than in leaves in other orientations.

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Pictures 3 and 4 show plants in cultivation (scans of old slides)

senecrassi-1-scan

Crassula tecta (part 1 of 3)

With their leaves covered in big, coarse papillae (tecta=covered), these great little plants are unmistakable. The papillae protect the leaves again too intense light and strong wind, thereby reducing transpiration.
Some forms of Cr. namaquensis look similar, but the papillae are different and the plants occur further north and west.

The rosettes are 2-6 cm in diameter and often much branched; they bear leaves 2-3.5 cm long and 0.5-1.2 (-1.5) cm wide, the old ones remaining attached to the stem.
The flowers are white to cream and appear from April to June.

The plants are sometimes locally abundant on gravelly plains and lower slopes throughout the Little Karoo and eastwards to  the Steytlerville area.

crastect 7790 2012-05-09

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crastect 2011-11-18 7102

Cheiridopsis namaquensis (part 1 of 2)

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

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Avonia papyracea (part 1 of 2)

Even if one has no knowledge of Latin, it is probably easy to understand that papyracea means papery. This refers to the thin, white scales that cover the stems.
These scales are in fact modified stipules: outgrowths of the base of the leaf stalk. By reflecting and diffusing light, they act as sunshades. This effect, combined with controlled aeration*, reduces evaporation. The scales are also able to trap dew.
*It has been noted that in hot, dry conditions the scales tightly overlap each other like roof tiles, whereas in cooler and therefore damper weather they can open out to some extent so that the leaves are more exposed.
As Gordon Rowley in “Anacampseros, Avonia, Grahamia” (1995) remarks, it seems surprising that such an efficient adaptation has, apparently, evolved only once.

The scales are about 5 mm long and wide and hide the minute leaves.
The stems are usually about 5-8 cm long and 0.7-1 cm thick, arising from a thickened tuber. As in other Avonia species, the stems that carry flower buds grow more or less horizontal, but become erect on the day of flowering and stay that way until the seeds have been dispersed.
The scented flowers are creamy white and appear in late spring and early summer.
There are two subspecies: subsp. papyracea occurs throughout the Little Karoo and is also found in the Great Karoo, whereas subsp. namaensis occurs in southern Namibia, the Richtersveld and Bushmanland. Both subspecies seem to feel most at home amongst white quartz pebbles.
According to the literature the main difference between the two is that in the first one, the edges of the scales are entire (without any teeth or other incisions) and in the second one saw-edged to toothed.
The following pictures show plants of subsp. papyracea.

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avonpapypap 2011-04-17057

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Antimima pygmaea (part 2 of 2)

It may be of interest to see what Prof. Schwantes in his magnum opus Flowering Stones and Mid-Day Flowers (1957) has to say about this “most remarkable and interesting species”: “This forms annually only two pairs of leaves to each growth which, however, are differently shaped. This phenomenon is called dimorphism of the leaf. The pair of leaves that appears at the beginning of the rainy season from out of the dry sheath is united into a long sheath at the base but developed normally above into widely separated, yawning, broad leaf tips. This pair of leaves with its comparatively broad surfaces that catch the light and absorb carbon dioxide as nourishment, provides food during the growth period. When the end of this period approaches there pushes out of the channel formed through the uniting of these normally developed leaves a peculiar, elongated, cylindrical structure which consists of two leaves joined right up to the tip. The very short ends are separated only by a slit, which shows that the growth actually consists of two thick leaves. Growths which consist of such closely united leaves are called plant bodies (corpusculum). The object of this close union can only be to reduce the evaporating surface as much as possible and to protect the young growth within from being dried up. The plant’s struggle to make the leaf pair as nearly spherical as possible is here obvious; as is known, the sphere is the form with the smallest surface area. Within these leaf pairs or plant bodies the next pair develops, which once more is less completely united. Inside the body a channel running its whole length remains open; the slowly developing leaf pair is fitted into this and draws from the plant body food and water until it has dried up to a parchment-like skin which completely surrounds the young pair so that not even the tip projects. In this condition the growth, well protected by the skin, lives through the dry period and when the rains begin the deeply buried pair of leaves quickly emerges from the skin surrounding it. In Ruschia pygmaea quite distinct leaf pairs are produced for the dry and for the rainy seasons, one of which has a large surface for assimilation, while the other serves for the protection of the resting pair.”

antipygm 2010-06-23#018
23 June 2010

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1 Oct. 2006

antipygm 2012-10-03_DSC7953
1 Oct. 2012

antipygm 7324#2012-01-29
29 Jan. 2012

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18 Feb. 2007