Description
Lithops hookeri is a medium to very large species, up to 46 X 35 mm, usually about 30 X 23 mm. with up to 10 or more heads (mostly 2-4). The bodies (paired leaves) are obconical, truncate, with the top surface flat to slightly convex. The face is elliptical more or less equal. The fissure is shallow 3-7 mm, the lobes are conjunct. This species is characterized by an obscure network of simple and forked groves and lines, and numerous irregular small island enclosed by groves. Margins are irregularly incise with narrow lines tapering out of the grows. This species is quite variable and the colours and face pattern varies considerably in plant from different provenance. L. hookeri comprises several more or less intergrading and distinct variety.
Desmond Cole field number C051 [vermiculate Form]: This population distinguishes for having dark red jagged lines.
Origin and Habitat
15 km NW of Strydenburg, South Africa.
Habitat: L. hookeri grows on different kind of stony ground comprising transluscent quartzite; amygdaloidal lava; amygdaloidal lava with some sandstone; sheared micaceous quartzite. Colours grey-white, brown, pink, grey, some white, red.
Cultivation and Propagation
It need an open mineral, fast draining mix and the maximum amount of light you are able to give them.
The basic cultivation routine is: Stop watering after flowering. Start watering after the old leaves completely dry. (Usually late March or Early April) Water freely during the growing season, soak the compost fully but allow it to dry out between waterings. Some growers fertilize frequently, some hardly ever. Keep them dry during the winter. Nearly all problems occur as a result of overwatering and poor ventilation especially when weather conditions are dull and cool or very humid.
Remarks: After flowering in the autumn and extending through winter season the plant doesn’t need watering, but they will still be growing, the new bodies will be increasing in size extracting water from the outer succulent leaves, allowing them to shrivel away. In fact the plant in this time extracts water and nutrient stored in the outer succulent leaves, allowing them to dehydrate relocating the water to the rest of the plant and to the new leaves that form during this period until the old leaves are reduced to nothing more than “thin papery shells”.
Notes
Lithops are partly subterranean, with only the clear ‘window’ in each leaf tip exposed above soil. A type of optical system exists whereby a layer of apical tissue rich in calcium oxalate crystals acts as a filter to intense sunlight before it reaches the thin chlorophyllous layer below. They are also called mimicry plants as they show a striking similarity to their background rocks and are difficult to detect when not in flower. These are the commonly known as pebble plants or living stones; each species is associated with one particular type of rock formation and occurs nowhere else. Its soil-embedded, subterranean growth form also reduces the need for chemical defences against herbivores.
Bibliography
Major refences and further lectures
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Heidrun E. K. Hartmann “Aizoaceae F – Z” Springer 2002
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Achim Hecktheuer “Mesembs, mehr als nur Lithops” Books on Demand GmbH Norderstedt. 2008
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Desmond T. Cole & Naureen A. Cole, Uwe Beyer, Yves Delange “Les Lithops” SUCCULENTES Spécial 2008 AIAPS (now Terra seca). 2008
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Desmond T. Cole & Naureen A. 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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Desmond T. Cole “Lithops – Flowering Stones” Acorn Books 1988
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Rudolf Heine “Lithops – lebende Steine” Neumann Verlag. 1986
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David L. Sprechman “Lithops” Associated University Presses, Inc. 1970
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Gert Cornelius Nel “Lithops” Hortors Limited, South Africa 1946
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Edgar Lamb “The illustrated reference on cacti and other succulents” Blandford Press. 1978
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Christopher Brickell, Royal Horticultural Society “RHS A-Z Encyclopedia of Garden Plants: K-Z., Volume 2” Kindersley, 2008
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G. C . Nel “Lithops: Plantae succulantae, rarissimae, in terra obscuratae, e famailia Aizoaceae, ex Africa australi” Hortors Limited, Cape Town, South Africa 1946
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Heidrun E. K. Hartmann “Illustrated Handbook of Succulent Plants: Aizoaceae F-Z” Springer, 2002
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Steven A. Hammer “Lithops: Joyaux du veld” Editions Quae, 25/nov/2010
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