Description
Lithops karasmontana (a.k.a. Stone plant) is a tiny perennial, caespitose, succulent plant resembling a grouping of tiny pebbles split down the middle like cleft hooves. It grows to a maximum eight of 4 cm above ground and spreads to form small clumps with up to 12 or more heads (usually 2-6). It is one of the more variable species, with uniformly coloured or variously ornamented plants, and yet with opaque or obscurely windowed forms; there is also a great variation in the colours. Plants from different localities show strikingly different colours or patterns, but all natural populations show some degree of variation among individuals, and in some all possible intermediates colours and pattens occur. The “mickbergensis” form has a quite uniform orange grey to pinkish-grey tops. It is variable.
Stem: Almost stemless.
Bodies (Paired leaves): Inverted cone-like, divided into 2 unequal-sized, conjunct and coalescent leaves. These leaves are modified for water storage as well as photosynthesis. Face elliptic-reniform 25-35 x 20-28 mm broad usually rugose. Top flat to slightly convex, fissure fairly deep, 4-10 mm long. Colours pale grey or bluish-grey on lower parts and shoulders, upper surfaces beige, to orange-grey on the flat sunken surfaces. Windows often absent. Margins indistinct grey tinged with various shades of orange-grey. Islands frequently only vaguely noticeable. Dusky dots absent or very inconspicuous.
The plant renews itself every year or so by putting out a new plantlet from between the two lobes. Once the new plant is full sized, the old lobes shrivel up and slough off as a snake skin does.
Flowers: Big up to 4,5 cm in diameter (mostly 25-35 mm) satiny white, narrow-rayed.
Blooming season: Late summer or early autumn.
Fruit: Seed capsules mostly 5-chambered, otherwise 4 or 6-chambered. Profile boat-shaped.
Seeds: Minuscule, yellow-brown; smooth to rugose.
Origin and Habitat
15 km NE of Grünau, Namibia
Notes
Lithops karasmontana is a choice example of the window-leaf ( fenestrate leaf) adaptation found in many other succulent species like Peperomia columnella, Fenestraria rhopalophylla, Haworthia truncata, Ophthalmophyllum friedrichiae, etc. These windowed plants usually grows buried in the ground with only the upper truncated portion of the thick, succulent leaves visible. Both the coalescent leaf pair of Lithops (shaped like an inverted cone) and the leaves of the other windowed plants have a more or less upright position with the leaf tips at the soil surface or protruding only a little from the soil. The leaf tips either are rounded or flattened. This windows leaf tip is free of green pigments. The greater part of the photosynthetic leaf surface, the mantle, is not exposed directly to sun light since the leaf is embedded into the soil and the solar radiation is transmitted by the colourless water storage tissue to the assimilatory tissue, so the photosynthetically active mantle gets light only from inside the leaf and not across the epidermis. Moreover this light is more or less evenly dispersed over the whole assimilatory tissue since the water storage tissue disperses the solar radiation. All species of Lithops and Ophthalmophyllum have coloured windows that matches with the colours of the soil and the pebbles of the plant’s habitat. While other window plants such as Haworthia maughanii have dark green pigmented window areas. This green colour, however, does not result from a pigmentation of the window area but is the result of light that penetrates the window and is transmitted across the water storage tissue.
Bibliography
Major references and further lectures
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Gert Cornelis Nel, “Lithops: Plantae Succulente, Rarissimae, in Terra Obsuratae, E Familia Aizoaceae, Ex Africa Australi” Hortors Limited, University Press, Stellenbosch. 1946
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Linda R. Berg “Introductory Botany: Plants, People, and the Environment” Cengage Learning, 02/Mar/2007
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Dieter J. Von Willert “Life strategies of succulents in deserts: with special reference to the Namib desert” CUP Archive, 1992
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Chris Mcintyre “Namibia” Bradt Travel Guides, 2007
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Neale (W. T.) & Co, Edgar Lamb “Neale’s photographic reference plates, 1949: Combining cacti and other succulents” Vol. 2 W. T. Neale & Co.
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RHS “A-Z encyclopedia of garden plants.” United Kingdom: Dorling Kindersley. 2008
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American Horticultural Society “The American Horticultural Society encyclopedia of garden plants” Macmillan, 30/Nov/1989
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H. E. K. Hartmann “Illustrated Handbook of Succulent Plants: Aizoaceae F-Z” Springer, 2002
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Schwantes, Gustav. “Flowering Stones and Mid-day Flowers” London: Ernst Benn. 1957
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S. M Walters “The European Garden Flora Flowering Plants: Casuarinaceae to Aristolochiaceae” Cambridge University Press, 1989
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Clive Innes “Complete Handbook of Cacti and Succulents” Van Nostrand Reinhold Company, 01/Dec/1981
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Cole, D. T. “Flowering stones” Acorn Books, Randburg. 1988
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Smith et al. “Mesembs of the World.” Briza.Pretoria 1998
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Leistner, O.A. (ed.), “Seed plants of southern Africa: families and genera” Strelitzia 10., National Botanical Institute, Pretoria 2000
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Achim Hecktheuer “Mesembs, mehr als nur Lithops” Books on Demand GmbH Norderstedt. 2008
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Cole “LITHOPS Flowering Stones” Cactus & Co. Libri. 2005
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Yasuhiko Shimada “The Genus Lithops” Dobun Shoin. 2001
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Rudolf Heine “Lithops - Lebende Steine” Neumann Verlag. 1986
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Bernd Schlösser “Lithops – Lebende Steine” Praktische Anleitung für die Zimmerkultur. BussinessPoint MEDIA. 2000
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Steven A. Hammer “Lithops – Treasures of the veld” British Cactus and Succulent Society. 1999
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David L. Sprechman “Lithops” Associated University Presses, Inc. 1970