Origin and Habitat: Calvinia District, Namaqualand, Northern Cape, South Africa, in a small area extending North West and East from Kalkstasie, and some 40 km N of the range of subsp. villetii, and West of the range of subsp. kennedyi.
Type Locality: unknown; it was probably East of Kalkstasie, somewhere near C230.
Habitat: Lithops villetiiSN|13246]]SN|13246]] subs. deboeri is native to dry winter rainfall areas where it grows in barren minerals terrains clinging to life in this harsh landscape. They live a precarious existence hidden beneath outcrops of dark coloured stones. They grow almost completely buried in the ground with only the upper truncated portion of the thick, succulent leaves visible. L. villetii subs. deboeri resist attacks from herbivorous predators by mimicking the local stone formations, in this case calcrete with some quartzite, calcrete with some sandstone, quartzite, shale and sandstone, and is almost impossible to distinguish from their surroundings until they erupt into vivid daisy-like white flowers. Colours of the background grey-white with some brown, grey; pinkish brown with some red, black, grey. When they are found, it is usually due to their large and brightly coloured flowers flowers.

• Lithops villetii subs. deboeri C258 35 km ENE of Gamoep, South Africa

• Lithops villetii L. Bolus
• Lithops villetii C194 50 km NNE of Grünau, Namibia
• Lithops villetii C195 TL: 30 km NNE of Loeriesfontein, South Africa

• Lithops villetii subs. deboeri (Schwantes) D.T.Cole
• Lithops deboeri Schwantes
• Lithops villetii subs. deboeri C230A TL: 75 km E of Gamoep, South Africa
• Lithops villetii subs. deboeri C231 75 km E of Gamoep, South Africa
• Lithops villetii subs. deboeri C258 35 km ENE of Gamoep, South Africa

• Lithops villetii subs. kennedyi (de Boer) D.T.Cole
• Lithops deboeri var. kennedyi (de Boer) O.R.Heine
• Lithops fulleri var. kennedyi de Boer
• Lithops villetii subs. kennedyi C123 TL: 90 km SSE of Pofadder, South Africa
• Lithops villetii subs. kennedyi C197 75 km S of Pofadder, South Africa
• Lithops villetii subs. kennedyi C199 75 km SSE of Pofadder, South Africa
• Lithops villetii subs. kennedyi C200A 80 km SSE of Pofadder, South Africa
• Lithops villetii subs. kennedyi C228 90 km S of Pofadder, South Africa
• Lithops villetii subs. kennedyi C229A 90 km S of Pofadder, South Africa

Description: Lithops villetii subs. deboeri is a fairly easy to identify subspecies of Lithops villetiiSN|13246]]SN|13246]]. Distinguished from the latter by its peculiar bluish or reddish-grey colouration, more irregular margins, more occluded windows and more numerous islands.
Habit: It grows solitary or forms clumps of up to 7 or more heads, mostly 2-4 and conforms to the typical Lithops morphology: two thick, fleshy windowed leaves separated by a crack from which a yellow flower appears. The windowed part allows light into the inner portion of the leaf where the process of photosynthesis is carried out.
Bodies (paired leaves): Truncate-cordate in profile, small to medium, 17-30 mm in diameter up to 3 cm high and about 18 mm wide at the fissure. Fissure shallow, 5-10 mm. Lobes conjunct or very slightly divergent. Face flush, elliptic-reniform; lobes equal-unequal. The upper surface is slightly rugose, variable in colour, usually greenish yellow, dark grey-green or brownish, slightly convex, while the sides are light greyish-brown or light brown. Windows usually occluded, infrequently completely open, opaque or obscurely translucent bluish, greenish, pinkish, reddish or purplish grey. Islands are numerous, small, usually distinct but irregular, occasionally reduced to hazy flecks, bluish, greenish, pinkish or reddish grey or brownish the edges of the islands (yellowish-brown in colour) are not always sharply defined. Margins distinct, somewhat in relief, very irregularly dentate or sinuate with numerous peninsulas some colour of islands . Channels mostly fairly narrow, irregular, various shades of opaque greenish or brownish grey or greyish green, brown, orange-brown or purplish brown. Dusky dots rarely visible even with a lens, very obscure. Rubrications absent.
Flowers: Daisy-like, diurnal, small to medium, 2-3 cm diameter. Petals satiny white.
Blooming season: Autumn (in habitat blooms in April)
Fruits: Capsules 6-parted. Profile boat-shaped, top flat. Face broadly elliptic. This capsule only opens when moistened, exposing the tiny seeds. In nature, falling rain drops splash out the seeds to a distance of a few centimetres to up to a metre or more from the parent plant. After the capsule dries up it closes again, protecting any seeds left behind.
Seeds: Yellow-brown to light brown, smooth to rugose.

Notes: Lithops villetiiSN|13246]]SN|13246]] is a choice example of the window-leaf (fenestrate leaf) adaptation found in many other succulent species like Peperomia columnella, Fenestraria rhopalophyllaSN|11322]]SN|11322]], Haworthia truncataSN|11540]]SN|11538]], Ophthalmophyllum friedrichiaeSN|14645]]SN|14645]], 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 maughaniSN|11538]]SN|11540]]i 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 refences and further lectures
1) Heidrun E. K. Hartmann (2002) “Aizoaceae F – Z” Springer
2) Achim Hecktheuer (2008) “Mesembs, mehr als nur Lithops” Books on Demand GmbH Norderstedt.
3) Desmond T. Cole & Naureen A. Cole, Uwe Beyer, Yves Delange (2008) “Les Lithops” SUCCULENTES Spécial 2008 AIAPS (now Terra seca).
4) Desmond T. Cole & Naureen A. Cole (2005) “LITHOPS Flowering Stones” Cactus & Co. Libri.
5) Yasuhiko Shimada (2001) “The Genus Lithops” Dobun Shoin. ISBN 4-8103-4066-X
6) Rudolf Heine (1986) “Lithops - Lebende Steine” Neumann Verlag.
7) Bernd Schlösser (2000) “Lithops – Lebende Steine” Praktische Anleitung für die Zimmerkultur. BussinessPoint MEDIA.
8) Steven A. Hammer (1999) “Lithops – Treasures of the veld” British Cactus and Succulent Society.
9) Desmond T. Cole (1988) “Lithops – Flowering Stones” Acorn Books CC.
10) Rudolf Heine (1986) “Lithops – lebende Steine” Neumann Verlag.
11) David L. Sprechman (1970) “Lithops” Associated University Presses, Inc.
12) Gert Cornelius Nel (1946) “Lithops” Hortors Limited, South Africa.

Cultivation and Propagation: L. villetii is relatively easy to grow but great care needs to be taken with soil, temperature, time and amount of watering. It is a winter growing species and heads for dormancy in summer.
Growth rate: It is slow growing but clustering in cultivation, if grown correctly, it will reward the grower with generous displays of flowers.
Soil: Since roots are quite shallow, use a sandy gravel mixture (e.g. 2 parts sand : 1 part clay loam : 1 part gravel) or a cactus mix with extra perlite or pumice. For best results, use a shallow pot, and only use the smallest diameter pot that will accommodate the plant. Clay pots help the plants to dry out between watering.
Waterings: Requires little water, otherwise its epidermis breaks (resulting in unsightly scars). Watering should be very sparing and regular only during the late autumn and early winter months, e.g. no more frequently than once in two weeks, but when watered, they should be drenched so that the water reaches the bottom of the container. Water minimally in summer, only when the plant starts shrivelling. It is also best to water in the mornings so that the excess water evaporates and the upper layers of soil dry out fairly quickly. No water should ever be allowed to stand around the roots.
Exposure: Keep cool and shaded in summer, needs full sun or light shade in the other seasons. High levels of light are needed in autumn to flower and for good plant development. The low intensity of sun light during the growing season of this species generally prevents the white flower flowers from opening.
Special Advice: Lithops are best planted in a sunny and airy part of the greenhouse, and not too close to the glass roof or sides of the house as the plants can overheat during hot spells.
Fertilization: Need a perfect fertilizer diet during the growing season. Feed them once during the growing season with a fertilizer specifically formulated for cactus and succulents (high potash fertilizer with a dilute low nitrogen), including all micro nutrients and trace elements diluted to ½ the strength recommended on the label. They thrive in poor soils and need a limited supplies of fertilizer to avoid the plants developing excess vegetation, which is easily attacked by fungal diseases. Some growers fertilize frequently, some hardly ever. However, for the highly succulent mesembs, fertilization is not really necessary.
Hardiness: Although the plant will survive mild frost if kept dry (hardy as low as -5° C) it should be protected from severe cold and prolonged frost conditions.
Rot: Rot is only a minor problem with mesembs if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much. The plant turns immediately to mush when over watered, or watered out of season. Care must be given in watering, keeping them warm and wet while growing, and cooler and dry when dormant.
Reproduction: Seeds, cuttings or division. Sow them in spring or autumn. Germination usually occurs within about a week or two. Seed germinate at 15-21 °C. Cover the seeds with a very fine layer of grit and water from below with a fungicide to prevent damping off. For the first 3-4 days cover the pots with a sheet of glass/clear perspex to keep the humidity levels high. Remove the glass and replace it with light shadecloth and mist once or twice a day for the next two weeks after which most seeds should have germinated. From then on mistings can be reduced to every second and then every third day as the little plants grow. The young plants can be transplanted after a year, and flowering can be achieved within 3-4 years. The seed will remain viable for many years provided it is stored in a cool dry place. It is also possible to divide a multiheaded plant, but lithops prefer to grow clustered together and many growers prefer to leave them undisturbed to see how large a cluster can get. To separate a cutting from a grown-up mother, lift the plant, carefully cut through the rootstock. Each cutting must contain one or more heads along with a fraction of root and permit them to dry out a couple of days, lay the cuttings on the soil and insert the stem end partially into the soil. Try to keep the cutting somewhat upright so that the roots are able to grow downward.