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{{short description|Genus of plants}} {{Short description|Genus of plants}}
{{Redirect|Living stone|the 1958 documentary film|The Living Stone}} {{Redirect|Living stone|the 1958 documentary film|The Living Stone}}
{{automatic taxobox {{Automatic taxobox
|image = Marloth-Lithops-drawing.jpg |image = Marloth-Lithops-drawing.jpg
|image_caption = ''Lithops'' sp. by ] |image_caption = ''Lithops'' sp. by ], 1929
|display_parents = 2 |display_parents = 2
|taxon = Lithops |taxon = Lithops
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}} }}


'''''Lithops''''' is a ] of ]s in the ice plant family, ]. Members of the genus are native to ]. The name is derived from the ] words {{wikt-lang|grc|λίθος}} ({{transl|grc|líthos}}), meaning "stone," and {{wikt-lang|grc|ὄψ}} ({{transl|grc|óps}}), meaning "face," referring to the stone-like appearance of the plants. They avoid being eaten by blending in with surrounding rocks and are often known as '''pebble plants''' or '''living stones'''. The formation of the name from the Ancient Greek "-ops" means that even a single plant is called a Lithops. '''''Lithops''''' is a ] of ]s in the ice plant family, ]. Members of the genus are native to ]. They avoid being eaten by herbivores with ] as small stones, and are often known as '''pebble plants''' or '''living stones'''.

"Lithops" is both the genus name and the common name, and is singular as well as plural. The name is derived from the ] words {{wikt-lang|grc|λίθος}} ({{transliteration|grc|líthos}}) 'stone' and {{wikt-lang|grc|ὄψ}} ({{transliteration|grc|óps}}) 'face', referring to the stone-like appearance of the plants.


== Description == == Description ==
]''. Two new leaf pairs are emerging between the old one, leading to a double-headed plant]] ]''. Two new leaf pairs are emerging between the old one, leading to a double-headed plant]]
Individual ''Lithops'' plants consist of one or more pairs of bulbous, almost fused ] opposite to each other and hardly any ]. The slit between the leaves contains the ] and produces ]s and new leaves. The leaves of ''Lithops'' are mostly buried below the surface of the ], with a partially or completely translucent top surface known as a ] which allows light to enter the interior of the leaves for ]. Individual ''Lithops'' plants consist of one or more pairs of bulbous, almost fused ] opposite each other and hardly any ]. The slit between the leaves contains the ] and produces ]s and new leaves. The leaves of ''Lithops'' are mostly buried below the surface of the ], with a partially or completely translucent top surface known as a ] which allows light to enter the interior of the leaves for ].<ref></ref>


During winter a new leaf pair, or occasionally more than one, grows inside the existing fused leaf pair. In ] the old leaf pair parts to reveal the new leaves and the old leaves will then dry up. ''Lithops'' leaves may shrink and disappear below ground level during ]. Lithops in habitat almost never have more than one leaf pair per head, presumably as an adaptation to the arid environment. Yellow or white flowers emerge from the fissure between the leaves after the new leaf pair has fully matured, one per leaf pair. This is usually in autumn, but can be before the summer ] in '']'' and after the winter ] in '']''. The flowers are often sweetly scented. During winter a new leaf pair, or occasionally more than one, grows inside the existing fused leaf pair. In ] the old leaf pair parts to reveal the new leaves and the old leaves will then dry up. ''Lithops'' leaves may shrink and disappear below ground level during ]. Yellow or white flowers emerge from the fissure between the leaves after the new leaf pair fully matures, one per leaf pair. This is usually in autumn, but can be before the summer ] in '']'' and after the winter ] in '']''. The flowers are often sweetly scented.
] budding leaves growing between the mature leaves.]] ] budding leaves growing between the mature leaves]]
The most startling ] of ''Lithops'' is the colouring of the leaves. The leaves are ], and the ] are patterned in various shades of cream, grey, and brown, with darker windowed areas, dots, and red lines, according to species and local conditions. The markings function as remarkable ] for the plant in its typical stone-like environment. As is typical of a window plant, the green tissue lines the inside of the leaves and is covered with ] tissue beneath the epidermal windows. The most startling ] of ''Lithops'' is the colouring of the leaves. The leaves are ], and the ] are patterned in various shades of cream, grey, and brown, with darker windowed areas, dots, and red lines, according to species and local conditions. The markings function as remarkable ] in its typically stony environment. As is typical of a window plant, the green tissue lines the inside of the leaves and is covered with ] tissue beneath the epidermal windows.


''Lithops'' are obligate ] and require ] from a separate plant. Like most ]s, Lithops fruit is a dry ] that opens when it becomes wet; some ]s may be ejected by falling raindrops, and the capsule re-closes when it dries out. Capsules may also sometimes detach and be distributed intact, or may disintegrate after several years. ''Lithops'' are obligate ] and require ] from a separate plant. Like most ]s, Lithops fruit is a dry ] that opens when it becomes wet; some ]s may be ejected by falling raindrops, and the capsule re-closes when it dries out. Capsules may also sometimes detach and be distributed intact, or may disintegrate after several years.
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== Distribution == == Distribution ==
]'']] ]'']]
''Lithops'' occur naturally across wide areas of ] and ], as well as small bordering areas in ] and possibly ], from sea level to high mountains. Nearly a thousand individual populations are documented, each covering just a small area of dry grassland, ], or bare rocky ground. Different ''Lithops'' species are preferentially found in particular environments, usually restricted to a particular type of rock. ''Lithops'' have not ]d outside this region. ''Lithops'' occur naturally across wide areas of ] and ], as well as small bordering areas in ] and possibly ], from sea level to high mountains. Nearly a thousand individual populations are documented, each covering just a small area of dry grassland, ], or bare rocky ground. Different ''Lithops'' species are preferentially found in particular environments, usually restricted to a particular type of rock. ''Lithops'' have not ] outside this region.


]fall in ''Lithops'' habitats ranges from approximately 700&nbsp;mm/year to near zero. Rainfall patterns range from exclusively summer rain to exclusively winter rain, with a few species relying almost entirely on dew formation for moisture. Temperatures are usually hot in summer and cool to cold in winter, but one species is found right at the coast with very moderate temperatures year round. ]fall in ''Lithops'' habitats ranges from approximately 700&nbsp;mm/year to near zero. Rainfall patterns range from exclusively summer rain to exclusively winter rain, with a few species relying almost entirely on dew formation for moisture. Temperatures are usually hot in summer and cool to cold in winter, but one species is found right at the coast with very moderate temperatures year round.
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== Cultivation == == Cultivation ==
] ]
''Lithops'' are popular ]s and many specialist ] growers maintain collections. ]s and plants are widely available in shops and over the ]. They are relatively easy to grow and care for if given sufficient sun and kept in well-draining soil. ''Lithops'' are popular ]s and many specialist ] growers maintain collections. ]s and plants are widely available in shops and over the ]. They are relatively easy to grow and care for if given sufficient sun and kept in well-draining soil.


Normal treatment in mild ] ]s is to keep them completely dry during winter, watering only when the old leaves have dried up and are replaced by a new leaf pair. Watering continues through autumn, when the plants flower, and then stops for winter. The best results are obtained in an environment with additional heat such as a greenhouse. In hotter ]s, ''Lithops'' will have a summer dormancy when they should be kept mostly dry, and they may require some water in winter. In ] climates, ''Lithops'' can be grown primarily in winter with a long summer dormancy. In all conditions, ''Lithops'' will be most active and need most water during autumn and each species will flower at approximately the same time. Normal treatment in mild ] ]s is to keep them completely dry during winter, watering only when the old leaves have dried up and are replaced by a new leaf pair. Watering continues through autumn, when the plants flower, and then stops for winter. The best results are obtained in an environment with additional heat such as a greenhouse. In hotter ]s, ''Lithops'' will have a summer dormancy when they should be kept mostly dry, and they may require some water in winter. In ] climates, ''Lithops'' can be grown primarily in winter with a long summer dormancy. In all conditions, ''Lithops'' will be most active and need most water during autumn and most species will flower at approximately the same time.


] ]
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''Lithops'' thrive best in a coarse, well-drained substrate. Any soil that retains too much water will cause the plants to burst their skins as they over-expand. Plants grown in strong light will develop hard strongly coloured skins which are resistant to damage and rot, although persistent overwatering will still be fatal. Excessive heat will kill potted plants as they cannot cool themselves by ] and rely on staying buried in cool soil below the surface. Commercial growers mix a mild fungicide or weak strength horticultural sulfur into the plant's water to prevent rotting. Lithops are sensitive to watering during hot weather, which can cause the plants to rot; in habitat the plants are often dormant when the temperatures are high, doing most of their growing during the cool months of the year. Low light levels will make the plants highly susceptible to rotting and fungal infection.<ref>{{cite book|author=Ed Storms|title=The New Growing the Mesembs|url=https://books.google.com/books?id=WC2vtgAACAAJ|year=1986|publisher=Storms}}</ref> ''Lithops'' thrive best in a coarse, well-drained substrate. Any soil that retains too much water will cause the plants to burst their skins as they over-expand. Plants grown in strong light will develop hard strongly coloured skins which are resistant to damage and rot, although persistent overwatering will still be fatal. Excessive heat will kill potted plants as they cannot cool themselves by ] and rely on staying buried in cool soil below the surface. Commercial growers mix a mild fungicide or weak strength horticultural sulfur into the plant's water to prevent rotting. Lithops are sensitive to watering during hot weather, which can cause the plants to rot; in habitat the plants are often dormant when the temperatures are high, doing most of their growing during the cool months of the year. Low light levels will make the plants highly susceptible to rotting and fungal infection.<ref>{{cite book|author=Ed Storms|title=The New Growing the Mesembs|url=https://books.google.com/books?id=WC2vtgAACAAJ|year=1986|publisher=Storms}}</ref>


In the ] the following species have gained the ]’s ]:-<ref>{{cite web | url= https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf | title = AGM Plants - Ornamental | date = July 2017 | page = 61 | publisher = Royal Horticultural Society | access-date = 25 March 2018}}</ref> In the ] the following species have gained the ]'s ]:<ref>{{cite web | url= https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf | title = AGM Plants - Ornamental | date = July 2017 | page = 61 | publisher = Royal Horticultural Society | access-date = 25 March 2018}}</ref>
{{div col|colwidth=30em}} {{div col|colwidth=30em}}
*'']''<ref>{{cite web | url = https://www.rhs.org.uk/Plants/10366/i-Lithops-karasmontana-i/Details *'']''<ref>{{cite web | url = https://www.rhs.org.uk/Plants/10366/i-Lithops-karasmontana-i/Details
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| title = RHS Plantfinder - ''Lithops schwantesii'' | access-date = 25 March 2018}}</ref> | title = RHS Plantfinder - ''Lithops schwantesii'' | access-date = 25 March 2018}}</ref>
{{div col end}} {{div col end}}

==Cultivars==
Mr Keith Green was appointed ] for ''Lithops'' in 2013, and recognises over 100 registered ]s.<ref name=scrapbook>{{cite web |url=https://scrapbooklithops.com/cultivars.html |title=The International Cultivar Registration Authority Register and Checklist for the genus Lithops N.E.Br. |website=Scrapbooklithops |author=Keith Green |access-date=2023-07-09 }}</ref>

Since ''Lithops'' are mostly propagated by seed, cultivars require to be stabilised as seed strains. Most cultivars are either abnormally green or abnormally red plants, lacking most of the normal leaf pigments. Some were initially found as isolated unusual plants in habitat, but increasingly have arisen from cultivation, sometimes by deliberately selecting mildly-coloured plants to achieve intense colours for a cultivar. The term "aberrant colour form" (acf.) has been used for these unusually-coloured ''Lithops''.<ref name=cole2006/>

There are also so-called "pattern cultivars" of ''Lithops'', seed strains which have been selectively-bred or stabilised from isolated unusual plants to have intensified or unusual leaf patterns, and sometimes unusual flowers. In some cases, these are ].<ref name=scrapbook/>


===Propagation=== ===Propagation===
] ]
Propagation of ''Lithops'' is by ] or ]. Cuttings can only be used to produce new plants after a plant has naturally divided to form multiple heads, so most propagation is by seed. ''Lithops'' can readily be pollinated by hand if two separate ]s of a species flower at the same time, and seed will be ] about 9 months later. Seed is easy to ], but the seedlings are small and vulnerable for the first year or two, and will not flower until at least two or three years old. Propagation of ''Lithops'' is by ] or ]. Cuttings can only be used to produce new plants after a plant has naturally divided to form multiple heads, so most propagation is by seed. ''Lithops'' can readily be pollinated by hand if two separate ]s of a species flower at the same time, and seed will be ] about 9 months later. Seed is easy to ], but the seedlings are small and vulnerable for the first year or two, and will not flower until at least two or three years old.

== Conservation status ==
At least half of the species listed in the ] are classified as endangered or threatened for various reasons, including poaching for the succulent horticultural trade, habitat degradation, and decreased or restricted range due to urban and agriculture expansion.<ref>{{Cite web |title=Species list: Lithops {{!}} Threatened Species Programme {{!}} SANBI Red List of South African Plants |url=http://redlist.sanbi.org/genus.php?genus=85 |access-date=2024-09-02 |website=redlist.sanbi.org}}</ref>
⚫ {| class="wikitable"
|+
!Species
!Conservation status
|-
|]
|VU
|-
|]
|VU
|-
|]
|VU
|-
|]
|NT
|-
|]
|EN
|-
|]
|Rare
|-
|]
|VU
|-
|]
|VU
|-
|] subsp. burchellii
|NT
|-
|Lithops lesliei subsp. lesliei
|VU
|-
|]
|VU
|-
|]
|VU
|-
|]
| VU
|-
|]
|VU
|-
|]
|NT
|-
|]
|VU

|}


== History == == History ==
] ]
The first scientific description of ''Lithops'' was made by ] and artist ], explorer of ], although he called it ''] turbiniforme''. In 1811, Burchell discovered a specimen when picking up a "curiously shaped pebble" from the ground.<ref>{{cite book |last=Cole |first=Desmond |last2=Cole |first2=Naureen |title=Lithops—Flowering Stones |publisher=Cactus & Co |year=2005 |isbn=88-900511-7-5}}</ref> Unfortunately the documented physical description was not detailed enough to be sure which ''Lithops'' he had discovered and the name ''Lithops turbiniformis'' is no longer used, although for many years it was applied to what is now known as '']''. The first scientific description of ''Lithops'' was made by ] and artist ], explorer of ], although he called it ''] turbiniforme''. In 1811, Burchell discovered a specimen when picking up a "curiously shaped pebble" from the ground.<ref name="cole2006"/> Unfortunately the documented physical description was not detailed enough to be sure which ''Lithops'' he had discovered and the name ''Lithops turbiniformis'' is no longer used, although for many years it was applied to what is now known as '']''.


Several more ''Lithops'' were published as '']'' ] until in 1922 ] started to split up the overly large genus on the basis of the ]. The ] ''Lithops'' was created and dozens more species were published in the following decades. Brown, ], ], ], and Louisa Bolus continued to document ''Lithops'' from across southern Africa, but there was little consensus on the relationships between them, or even which populations should be grouped as species. As recently as the 1950s, the genus remained rather unknown in cultivation and was not well understood ]. Several more ''Lithops'' were published as ''Mesembryanthemum'' ] until in 1922 ] started to split up the overly large genus on the basis of the ]. The ] ''Lithops'' was created and dozens more species were published in the following decades. Brown, ], ], ], and Louisa Bolus continued to document ''Lithops'' from across southern Africa, but there was little consensus on the relationships between them, or even which populations should be grouped as species. As recently as the 1950s, the genus remained rather unknown in cultivation and was not well understood ].


In the 1950s, Desmond and Naureen Cole began to study ''Lithops''. Together, the couple visited nearly all natural habitats of the different lithops populations and collected samples from approximately 400. They document and identify them, assigning a number, which is now known as the Cole number still used today all around the world. They studied and revised the genus, in 1988 publishing a definitive book (Lithops: Flowering Stones) describing the ], ], and ] which have been accepted ever since. In the 1950s, Desmond and Naureen Cole began to study ''Lithops''. Together, the couple visited nearly all natural habitats of the different lithops populations and collected samples from approximately 400. They document and identify them, assigning a number, which is now known as the Cole number still used today all around the world. They studied and revised the genus, in 1988 publishing a definitive book (''Lithops: Flowering Stones'') describing the ], ], and ] which have been accepted ever since.


Because their camouflage is so effective, new species continue to be discovered, sometimes in remote regions of Namibia and South Africa, and sometimes in well-populated areas where they simply had been overlooked for generations. Recent discoveries include '']'' in 1994, '']'' in 2000, and '']'' in 2006. Because their camouflage is so effective, new species continue to be discovered. Recent discoveries include '']'' in 1994, '']'' in 2000, and '']'' in 2006.<ref>{{Cite journal |last1=Eller |first1=Benno M. |last2=Ruess |first2=Beatrice |date=1982 |title=Water relations of Lithops plants embedded into the soil and exposed to free air |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1399-3054.1982.tb00300.x |journal=Physiologia Plantarum |language=en |volume=55 |issue=3 |pages=329–334 |doi=10.1111/j.1399-3054.1982.tb00300.x |issn=0031-9317}}</ref>
{{clear}} {{clear}}


== Taxonomy == == Taxonomy ==
⚫ Many of the species listed have named ] or ] and some have many regional ]s identified by old names or habitat locations. Identification of species is primarily by flower colour and leaf patterns.


]
⚫ {| class=wikitable

⚫ |+Lithops<ref>{{cite book |editor=Hartmann, H.E.K. |title=Illustrated Handbook of Succulent Plants: Aizoaceae F-Z |publisher=Springer |year=2001 |isbn=3-540-41723-0}}</ref>
⚫ Many of the species listed have named ] or ] and some have many regional ]s identified by old names or habitat locations. Identification of species is primarily by flower colour and leaf patterns. The species list here follows Cole & Cole (2006).<ref name=cole2006/>

{| class=wikitable sortable
⚫ |+''Lithops''<ref name=hartmann2001>{{cite book |editor=Hartmann, H.E.K. |title=Illustrated Handbook of Succulent Plants: Aizoaceae F-Z |publisher=Springer |year=2001 |isbn=3-540-41723-0}}</ref>
|- |-
!Specific epithet !Specific epithet
!Meaning !Meaning
|- |-
|'']''<ref>{{cite journal |last=Cole |first=Desmond |title=Cactus&Co Journal |publisher=Cactus&Co |volume=X(1) |pages=57–59 |year=2006}}</ref> |'']''<ref>{{cite journal |last=Cole |first=Desmond |title=Cactus&Co Journal |journal=Cactus&Co |volume=X(1) |pages=57–59 |year=2006}}</ref>
|of the friends |of the friends
|- |-
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|named after Frantz de Laet |named after Frantz de Laet
|- |-
|'']'' (a.k.a. ''lydiae'') |'']''
|tawny head |tawny head
|- |-
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|- |-
|'']'' |'']''
|named after Dr. Albertus Geyer |named after Albertus Geyer
|- |-
|'']'' |'']''
|thin lined |thin lined
|- |-
|'']'' (a.k.a. ''salicola'' var. ''reticulata'') |'']''
|named after ] |named after ]
|- |-
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|- |-
|'']'' |'']''
|named after the location 'hermetically sealed', ] |named after the 'hermetically sealed' location, ]
|- |-
|'']'' |'']''
|named after Adolar 'Hans' Herre |named after Adolar 'Hans' Herre
|- |-
|'']'' (a.k.a. ''dabneri'', ''marginata'', ''turbiniformis'' var. ''lutea'') |'']''
|named after ] |named after ]
|- |-
|'']'' (a.k.a. ''fulleri'') |'']''
|named after Dr. Julius Derenberg |named after Julius Derenberg
|- |-
|'']'' |'']''
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|named after T. N. Leslie |named after T. N. Leslie
|- |-
|'']'' (a.k.a. ''terricolor'', ''peersii'') |'']''
|of a place |of a place
|- |-
|'']'' (a.k.a. ''diutina'', ''framesii'', ''umdausensis'') |'']''
|marbled |marbled
|- |-
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|olive-green |olive-green
|- |-
|'']'' (a.k.a. ''rubra'') |'']''
|eye-like |eye-like
|- |-
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|- |-
|'']'' |'']''
|had been confused with '']'' (a.k.a. ''Mesembryanthemum truncatellum'') |had been confused with '']''
|- |-
|'']'' |'']''
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|warty |warty
|- |-
|'']'' (a.k.a. ''deboeri'') |'']''
|named after Dr. C. T. Villet |named after C. T. Villet
|- |-
|'']'' |'']''
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|named after Werner Triebner |named after Werner Triebner
|} |}

Although the species, subspecies, and varieties published by Cole & Cole<ref name=cole2006>{{cite book |last1=Cole |first1=Desmond |last2=Cole |first2=Naureen |title=Lithops—Flowering Stones |publisher=Cactus & Co |year=2005 |isbn=88-900511-7-5}}</ref> largely remain accepted and in widespread use,<ref name=hartmann2001/> some variations have been published by other authors. Some published changes since 2006 include:
* reducing ''L. amicorum'' to a subspecies of ''L. karasmontana''; combining ''L. karasmontana'' ssp. ''bella'' and ssp. ''eberlanzii'' into one subspecies; and combining ''L. herrei'' with ''L. optica''.<ref>{{cite journal |doi=10.1073/pnas.1100628108 |title=Contemporaneous and recent radiations of the world's major succulent plant lineages |year=2011 |last1=Arakaki |first1=Mónica |last2=Christin |first2=Pascal-Antoine |last3=Nyffeler |first3=Reto |last4=Lendel |first4=Anita |last5=Eggli |first5=Urs |last6=Ogburn |first6=R. Matthew |last7=Spriggs |first7=Elizabeth |last8=Moore |first8=Michael J. |last9=Edwards |first9=Erika J. |journal=Proceedings of the National Academy of Sciences |volume=108 |issue=20 |pages=8379–8384 |pmid=21536881 |pmc=3100969 |bibcode=2011PNAS..108.8379A |doi-access=free }}</ref>
* raising ''L. dendritica'' and ''L. eberlanzii'' to species level and dropping all the separate varieties of ''L. karasmontana''.<ref>{{cite journal |doi=10.25223/brad.n38.2020.a20 |title=The form, structure and size of Lithops N.E.Br. Seeds and the taxonomic implications |year=2020 |last1=Earlé |first1=Roy A. |last2=Young |first2=Andrew J. |journal=Bradleya |volume=2020 |issue=38 |page=195 |s2cid=220072147 }}</ref>
* raising ''L. bella'', ''L. burchellii'', ''L. euniceae'', and ''L. glaudinae'' to species level; combining ''L. dorotheae'' and ''L schwantesii'' var. ''marthae'' under ''L. dinteri''; combining ''L. francisci'', ''L. gesinae'', and ''L. hermetica''; combining ''L. geyeri'' under ''L. herrei''; dropping separate subspecies of ''L. julii'' and ''L. gracilidelineata''; splitting ssp. ''archerae'', ''dendritica'' and ''groendrayensis'' from ''L. pseudotruncatella'' as ''L. dendritica''; and dropping separate varieties under ''L. villetii''.<ref>{{cite journal |title=Ein neuer taxonomischer Ansatz für die Gattung Lithops N.E.Br. |author=H Jainta |journal=Avonia |date=2019 |volume=37 |issue=1 }}</ref>

One study of ] ] (trnS-trnG intergenic spacer), nuclear ribosomal ] (nrITS) sequences and ] data found that Lithops was not ] since '']'', '']'', and '']'' were involved. It identified 9 clades which did not closely frame the accepted 37 species.<ref>{{cite journal |doi=10.1111/j.1438-8677.2010.00354.x |title=Genetic differentiation in the genus Lithops L. (Ruschioideae, Aizoaceae) reveals a high level of convergent evolution and reflects geographic distribution |year=2011 |last1=Kellner |first1=A. |last2=Ritz |first2=C. M. |last3=Schlittenhardt |first3=P. |last4=Hellwig |first4=F. H. |journal=Plant Biology |volume=13 |issue=2 |pages=368–380 |pmid=21309984 |doi-access=free |bibcode=2011PlBio..13..368K }}</ref>


==Gallery== ==Gallery==
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{{Reflist}} {{Reflist}}


==Literature== == Bibliography ==

⚫ * {{cite book |last=Jainta |first=Harald | title=Wild Lithops |publisher=Klaus Hess Verlag |year=2017 |isbn= 978-3-933117-93-9}}
* {{cite book |last=Cole |first=Desmond T | title=Lithops—Flowering Stones |publisher=Acorn Books |year=1988 |isbn=0-620-09678-0}} * {{cite book |last=Jainta |first=Harald | title=Wild Lithops |publisher=Klaus Hess Verlag |year=2017 |isbn= 978-3-933117-93-9 |ref=none}}
* {{cite book |last=Cole |first=Desmond |author2=Cole, Naureen | title=Lithops—Flowering Stones |publisher=Cactus & Co |year=2005 |isbn=88-900511-7-5}} * {{cite book |last=Cole |first=Desmond T | title=Lithops—Flowering Stones |publisher=Acorn Books |year=1988 |isbn=0-620-09678-0 |ref=none}}
* {{cite book |last=Hammer |first=Steven | title=Lithops: Treasures of the Veld |publisher=BCCS |year=1999 | isbn=0-902099-64-7}} * {{cite book |last=Cole |first=Desmond |author2=Cole, Naureen | title=Lithops—Flowering Stones |publisher=Cactus & Co |year=2005 |isbn=88-900511-7-5 |ref=none}}
* {{cite book |last=Schwantes |first=Gustav | title=Flowering Stones and Mid-day Flowers |publisher=London: Ernst Benn | year=1957 }} * {{cite book |last=Hammer |first=Steven | title=Lithops: Treasures of the Veld |publisher=BCCS |year=1999 |isbn=0-902099-64-7 |ref=none}}
⚫ * {{cite book |last=Schwantes |first=Gustav | title=Flowering Stones and Mid-day Flowers |publisher=London: Ernst Benn |year=1957 |ref=none}}


==External links== ==External links==
Line 211: Line 288:
* (UK) * (UK)
* *
* and
*
* (François Hoes, Belgium)
* (Catalan info + translator)
* (Spanish info)
* (General info & habitat photographs) * (General info & habitat photographs)


{{Taxonbar|from=Q133283}} {{Taxonbar|from=Q133283}}
{{Authority control}}


] ]
] ]
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Latest revision as of 12:32, 27 November 2024

Genus of plants "Living stone" redirects here. For the 1958 documentary film, see The Living Stone.

Lithops
Lithops sp. by Rudolf Marloth, 1929
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Aizoaceae
Subfamily: Ruschioideae
Tribe: Ruschieae
Genus: Lithops
N.E.Br.
Species

See text

Lithops is a genus of succulent plants in the ice plant family, Aizoaceae. Members of the genus are native to southern Africa. They avoid being eaten by herbivores with their camouflage as small stones, and are often known as pebble plants or living stones.

"Lithops" is both the genus name and the common name, and is singular as well as plural. The name is derived from the Ancient Greek words λίθος (líthos) 'stone' and ὄψ (óps) 'face', referring to the stone-like appearance of the plants.

Description

Lithops hookeri. Two new leaf pairs are emerging between the old one, leading to a double-headed plant

Individual Lithops plants consist of one or more pairs of bulbous, almost fused leaves opposite each other and hardly any stem. The slit between the leaves contains the meristem and produces flowers and new leaves. The leaves of Lithops are mostly buried below the surface of the soil, with a partially or completely translucent top surface known as a leaf window which allows light to enter the interior of the leaves for photosynthesis.

During winter a new leaf pair, or occasionally more than one, grows inside the existing fused leaf pair. In spring the old leaf pair parts to reveal the new leaves and the old leaves will then dry up. Lithops leaves may shrink and disappear below ground level during drought. Yellow or white flowers emerge from the fissure between the leaves after the new leaf pair fully matures, one per leaf pair. This is usually in autumn, but can be before the summer solstice in L. pseudotruncatella and after the winter solstice in L. optica. The flowers are often sweetly scented.

Longitudinal section of a Lithops plant, showing the epidermal window at the top, the translucent succulent tissue, the green photosynthetic tissue, and the decussate budding leaves growing between the mature leaves

The most startling adaptation of Lithops is the colouring of the leaves. The leaves are fenestrated, and the epidermal windows are patterned in various shades of cream, grey, and brown, with darker windowed areas, dots, and red lines, according to species and local conditions. The markings function as remarkable camouflage for the plant in its typically stony environment. As is typical of a window plant, the green tissue lines the inside of the leaves and is covered with translucent tissue beneath the epidermal windows.

Lithops are obligate outcrossers and require pollination from a separate plant. Like most mesembs, Lithops fruit is a dry capsule that opens when it becomes wet; some seeds may be ejected by falling raindrops, and the capsule re-closes when it dries out. Capsules may also sometimes detach and be distributed intact, or may disintegrate after several years.

Distribution

Large stand of Lithops salicola

Lithops occur naturally across wide areas of Namibia and South Africa, as well as small bordering areas in Botswana and possibly Angola, from sea level to high mountains. Nearly a thousand individual populations are documented, each covering just a small area of dry grassland, veld, or bare rocky ground. Different Lithops species are preferentially found in particular environments, usually restricted to a particular type of rock. Lithops have not naturalised outside this region.

Rainfall in Lithops habitats ranges from approximately 700 mm/year to near zero. Rainfall patterns range from exclusively summer rain to exclusively winter rain, with a few species relying almost entirely on dew formation for moisture. Temperatures are usually hot in summer and cool to cold in winter, but one species is found right at the coast with very moderate temperatures year round.

Cultivation

Group of Lithops sp. dividing and producing new leaf growth.

Lithops are popular house plants and many specialist succulent growers maintain collections. Seeds and plants are widely available in shops and over the Internet. They are relatively easy to grow and care for if given sufficient sun and kept in well-draining soil.

Normal treatment in mild temperate climates is to keep them completely dry during winter, watering only when the old leaves have dried up and are replaced by a new leaf pair. Watering continues through autumn, when the plants flower, and then stops for winter. The best results are obtained in an environment with additional heat such as a greenhouse. In hotter climates, Lithops will have a summer dormancy when they should be kept mostly dry, and they may require some water in winter. In tropical climates, Lithops can be grown primarily in winter with a long summer dormancy. In all conditions, Lithops will be most active and need most water during autumn and most species will flower at approximately the same time.

Lithops olivacea

Lithops thrive best in a coarse, well-drained substrate. Any soil that retains too much water will cause the plants to burst their skins as they over-expand. Plants grown in strong light will develop hard strongly coloured skins which are resistant to damage and rot, although persistent overwatering will still be fatal. Excessive heat will kill potted plants as they cannot cool themselves by transpiration and rely on staying buried in cool soil below the surface. Commercial growers mix a mild fungicide or weak strength horticultural sulfur into the plant's water to prevent rotting. Lithops are sensitive to watering during hot weather, which can cause the plants to rot; in habitat the plants are often dormant when the temperatures are high, doing most of their growing during the cool months of the year. Low light levels will make the plants highly susceptible to rotting and fungal infection.

In the United Kingdom the following species have gained the Royal Horticultural Society's Award of Garden Merit:

Cultivars

Mr Keith Green was appointed International Cultivar Registration Authority for Lithops in 2013, and recognises over 100 registered cultivars.

Since Lithops are mostly propagated by seed, cultivars require to be stabilised as seed strains. Most cultivars are either abnormally green or abnormally red plants, lacking most of the normal leaf pigments. Some were initially found as isolated unusual plants in habitat, but increasingly have arisen from cultivation, sometimes by deliberately selecting mildly-coloured plants to achieve intense colours for a cultivar. The term "aberrant colour form" (acf.) has been used for these unusually-coloured Lithops.

There are also so-called "pattern cultivars" of Lithops, seed strains which have been selectively-bred or stabilised from isolated unusual plants to have intensified or unusual leaf patterns, and sometimes unusual flowers. In some cases, these are hybrids.

Propagation

Lithops seedlings

Propagation of Lithops is by seed or cuttings. Cuttings can only be used to produce new plants after a plant has naturally divided to form multiple heads, so most propagation is by seed. Lithops can readily be pollinated by hand if two separate clones of a species flower at the same time, and seed will be ripe about 9 months later. Seed is easy to germinate, but the seedlings are small and vulnerable for the first year or two, and will not flower until at least two or three years old.

Conservation status

At least half of the species listed in the Red List of South African Plants are classified as endangered or threatened for various reasons, including poaching for the succulent horticultural trade, habitat degradation, and decreased or restricted range due to urban and agriculture expansion.

Species Conservation status
Lithops aucampiae VU
Lithops coleorum VU
Lithops dinteri VU
Lithops divergens NT
Lithops dorotheae EN
Lithops geyeri Rare
Lithops helmutii VU
Lithops herrei VU
Lithops lesliei subsp. burchellii NT
Lithops lesliei subsp. lesliei VU
Lithops meyeri VU
Lithops naureeniae VU
Lithops olivacea VU
Lithops otzeniana VU
Lithops salicola NT
Lithops viridis VU

History

Seven-day time-lapse

The first scientific description of Lithops was made by botanist and artist William John Burchell, explorer of South Africa, although he called it Mesembryanthemum turbiniforme. In 1811, Burchell discovered a specimen when picking up a "curiously shaped pebble" from the ground. Unfortunately the documented physical description was not detailed enough to be sure which Lithops he had discovered and the name Lithops turbiniformis is no longer used, although for many years it was applied to what is now known as Lithops hookeri.

Several more Lithops were published as Mesembryanthemum species until in 1922 N E Brown started to split up the overly large genus on the basis of the capsules. The genus Lithops was created and dozens more species were published in the following decades. Brown, Gustav Schwantes, Kurt Dinter, Gert Nel, and Louisa Bolus continued to document Lithops from across southern Africa, but there was little consensus on the relationships between them, or even which populations should be grouped as species. As recently as the 1950s, the genus remained rather unknown in cultivation and was not well understood taxonomically.

In the 1950s, Desmond and Naureen Cole began to study Lithops. Together, the couple visited nearly all natural habitats of the different lithops populations and collected samples from approximately 400. They document and identify them, assigning a number, which is now known as the Cole number still used today all around the world. They studied and revised the genus, in 1988 publishing a definitive book (Lithops: Flowering Stones) describing the species, subspecies, and varieties which have been accepted ever since.

Because their camouflage is so effective, new species continue to be discovered. Recent discoveries include L. coleorum in 1994, L. hermetica in 2000, and L. amicorum in 2006.

Taxonomy

Lithops fulviceps 'Aurea', green-bodied cultivar

Many of the species listed have named subspecies or varieties and some have many regional forms identified by old names or habitat locations. Identification of species is primarily by flower colour and leaf patterns. The species list here follows Cole & Cole (2006).

Lithops
Specific epithet Meaning
amicorum of the friends
aucampiae named after Juanita Aucamp
bromfieldii named after H. Bromfield
coleorum named after Desmond & Naureen Cole
comptonii named after Prof. Robert Harold Compton
dinteri named after Moritz Kurt Dinter
divergens divergent lobes
dorotheae named after Dorothea Huyssteen
francisci named after Frantz de Laet
fulviceps tawny head
gesineae named after Gesine de Boer
geyeri named after Albertus Geyer
gracilidelineata thin lined
hallii named after Harry Hall
helmutii named after Helmut Meyer
hermetica named after the 'hermetically sealed' location, Sperrgebiet
herrei named after Adolar 'Hans' Herre
hookeri named after Sir Joseph Hooker
julii named after Julius Derenberg
karasmontana named after the Great Karas Mountains
lesliei named after T. N. Leslie
localis of a place
marmorata marbled
meyeri named after Rev. Gottlieb Meyer
naureeniae named after Naureen Cole
olivacea olive-green
optica eye-like
otzeniana named after M. Otzen
pseudotruncatella had been confused with Conophytum truncatum
ruschiorum named after Rusch family
salicola salt-dweller
schwantesii named after Gustav Schwantes
vallis-mariae named after the location Mariental (Latinised)
verruculosa warty
villetii named after C. T. Villet
viridis green
werneri named after Werner Triebner

Although the species, subspecies, and varieties published by Cole & Cole largely remain accepted and in widespread use, some variations have been published by other authors. Some published changes since 2006 include:

  • reducing L. amicorum to a subspecies of L. karasmontana; combining L. karasmontana ssp. bella and ssp. eberlanzii into one subspecies; and combining L. herrei with L. optica.
  • raising L. dendritica and L. eberlanzii to species level and dropping all the separate varieties of L. karasmontana.
  • raising L. bella, L. burchellii, L. euniceae, and L. glaudinae to species level; combining L. dorotheae and L schwantesii var. marthae under L. dinteri; combining L. francisci, L. gesinae, and L. hermetica; combining L. geyeri under L. herrei; dropping separate subspecies of L. julii and L. gracilidelineata; splitting ssp. archerae, dendritica and groendrayensis from L. pseudotruncatella as L. dendritica; and dropping separate varieties under L. villetii.

One study of non-coding chloroplast DNA (trnS-trnG intergenic spacer), nuclear ribosomal internal transcribed spacer (nrITS) sequences and AFLP data found that Lithops was not monophyletic since Dinteranthus, Schwantesia, and Lapidaria were involved. It identified 9 clades which did not closely frame the accepted 37 species.

Gallery

  • Lithops sp. Blooms emerge between the leaves in autumn. Lithops sp. Blooms emerge between the leaves in autumn.
  • Lithops sp. Some species have flowers large enough to obscure the leaves. They open in the afternoon and close in the evening. Lithops sp. Some species have flowers large enough to obscure the leaves. They open in the afternoon and close in the evening.
  • Sculpture of lithops, National Botanical Gardens of Ireland Sculpture of lithops, National Botanical Gardens of Ireland

References

  1. "Genus: Lithops N. E. Br". Germplasm Resources Information Network. United States Department of Agriculture. 2009-06-09. Archived from the original on 2012-10-11. Retrieved 2011-04-09.
  2. Best of Both Worlds: Simultaneous High-Light and Shade-Tolerance Adaptations within Individual Leaves of the Living Stone Lithops aucampiae
  3. Ed Storms (1986). The New Growing the Mesembs. Storms.
  4. "AGM Plants - Ornamental" (PDF). Royal Horticultural Society. July 2017. p. 61. Retrieved 25 March 2018.
  5. "RHS Plantfinder - Lithops karasmontana". Retrieved 25 March 2018.
  6. "RHS Plantfinder - Lithops olivacea". Retrieved 25 March 2018.
  7. "RHS Plantfinder - Lithops pseudotruncatella". Retrieved 25 March 2018.
  8. "RHS Plantfinder - Lithops salicola". Retrieved 25 March 2018.
  9. "RHS Plantfinder - Lithops schwantesii". Retrieved 25 March 2018.
  10. ^ Keith Green. "The International Cultivar Registration Authority Register and Checklist for the genus Lithops N.E.Br". Scrapbooklithops. Retrieved 2023-07-09.
  11. ^ Cole, Desmond; Cole, Naureen (2005). Lithops—Flowering Stones. Cactus & Co. ISBN 88-900511-7-5.
  12. "Species list: Lithops | Threatened Species Programme | SANBI Red List of South African Plants". redlist.sanbi.org. Retrieved 2024-09-02.
  13. Eller, Benno M.; Ruess, Beatrice (1982). "Water relations of Lithops plants embedded into the soil and exposed to free air". Physiologia Plantarum. 55 (3): 329–334. doi:10.1111/j.1399-3054.1982.tb00300.x. ISSN 0031-9317.
  14. ^ Hartmann, H.E.K., ed. (2001). Illustrated Handbook of Succulent Plants: Aizoaceae F-Z. Springer. ISBN 3-540-41723-0.
  15. Cole, Desmond (2006). "Cactus&Co Journal". Cactus&Co. X(1): 57–59.
  16. Arakaki, Mónica; Christin, Pascal-Antoine; Nyffeler, Reto; Lendel, Anita; Eggli, Urs; Ogburn, R. Matthew; Spriggs, Elizabeth; Moore, Michael J.; Edwards, Erika J. (2011). "Contemporaneous and recent radiations of the world's major succulent plant lineages". Proceedings of the National Academy of Sciences. 108 (20): 8379–8384. Bibcode:2011PNAS..108.8379A. doi:10.1073/pnas.1100628108. PMC 3100969. PMID 21536881.
  17. Earlé, Roy A.; Young, Andrew J. (2020). "The form, structure and size of Lithops N.E.Br. Seeds and the taxonomic implications". Bradleya. 2020 (38): 195. doi:10.25223/brad.n38.2020.a20. S2CID 220072147.
  18. H Jainta (2019). "Ein neuer taxonomischer Ansatz für die Gattung Lithops N.E.Br". Avonia. 37 (1).
  19. Kellner, A.; Ritz, C. M.; Schlittenhardt, P.; Hellwig, F. H. (2011). "Genetic differentiation in the genus Lithops L. (Ruschioideae, Aizoaceae) reveals a high level of convergent evolution and reflects geographic distribution". Plant Biology. 13 (2): 368–380. Bibcode:2011PlBio..13..368K. doi:10.1111/j.1438-8677.2010.00354.x. PMID 21309984.

Bibliography

  • Jainta, Harald (2017). Wild Lithops. Klaus Hess Verlag. ISBN 978-3-933117-93-9.
  • Cole, Desmond T (1988). Lithops—Flowering Stones. Acorn Books. ISBN 0-620-09678-0.
  • Cole, Desmond; Cole, Naureen (2005). Lithops—Flowering Stones. Cactus & Co. ISBN 88-900511-7-5.
  • Hammer, Steven (1999). Lithops: Treasures of the Veld. BCCS. ISBN 0-902099-64-7.
  • Schwantes, Gustav (1957). Flowering Stones and Mid-day Flowers. London: Ernst Benn.

External links

Taxon identifiers
Lithops
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