View source for Saxifragaceae

{{Short description|Family of flowering plants in the Eudicot order Saxifragales}}
{{Automatic taxobox
|image = Foamflower.jpg
|image_caption = ''[[Tiarella]]''<br/>(Foamflower)
|taxon = Saxifragaceae
|authority = [[Antoine Laurent de Jussieu|Juss.]]
|subdivision_ranks = Clades
|subdivision = See text
|range_map = Saxifragaceae Distribution.svg
|range_map_caption = The range of Saxifragaceae
|type_genus = ''[[Saxifraga]]''
|type_genus_authority = [[Carl Linnaeus|L.]]
}}
[[File:Saxifraga granulata 140505.jpg|thumb|upright|''[[Saxifraga granulata]]''|alt=Flowers of Saxifraga granulata]]
[[File:Astilbe rivularis - Flickr - peganum (1).jpg|thumb|upright|''[[Astilbe rivularis]]''|alt=Astilbe rivularis]]

'''Saxifragaceae''' is a family of [[Herbaceous plant|herbaceous]] [[Perennial plant|perennial]] [[flowering plant]]s, within the [[core eudicot]] [[Order (biology)|order]] Saxifragales. The [[Taxonomy (biology)|taxonomy]] of the family has been greatly revised and the scope much reduced in the era of [[Molecular phylogenetics|molecular phylogenetic]] analysis. The family is divided into ten [[clade]]s, with about 640 known species in about 35 accepted [[genera]]. About half of these consist of a single species, but about 400 of the species are in the type genus ''[[Saxifraga]]''. The family is predominantly distributed in the northern hemisphere, but also in the Andes in South America.

== Description  ==
{{Technical|section|date=August 2020}}
Species are [[herbaceous]] [[perennials]] (rarely [[Annual plant|annual]] or [[biennial]]), sometimes [[succulent]] or [[xerophytic]], often with perennating [[rhizome]]s. The [[leaves]] are usually basally aggregated in alternate rosettes, sometimes on [[inflorescence]] stems. They are usually simple, rarely pinnately or palmately compound. Their margins may be entire, deeply lobed, cleft, crenate or dentate and petiolate with stipules.{{sfn|Byng|2014}}{{sfn|Christenhusz et al|2017}}

The inflorescences are bracteate racemes or cymes. The [[flower]]s are [[hermaphroditic]] (bisexual), rarely unisexual ([[androdioecious]]), [[actinomorphic]] (rarely [[zygomorphic]]). The [[perianth]] is placed on a hypanthium that may be free or may be partly fused with the [[Ovary (botany)|ovary]] (which is then semi-inferior). There are usually five [[sepal]]s, but there may be three to ten, fused with the hypanthium, occasionally petaloid. The [[petal]]s are clawed, sometimes cleft at the tip or finely dissected. Flowers have five to ten [[stamen]]s, free and opposite the petals, with the anthers usually basifixed and opening by lengthwise slits. The ovary is inferior to semi-inferior with two (sometimes three) [[carpel]]s usually fused at the base, sometimes free, each topped with stylodium and capitate stigma. The [[ovule]]s are few to many, with axile or parietal placentation and two to three [[Stigma (botany)#Style|styles]]. The [[fruit]] is usually a septicidal capsule or follicle, with numerous small [[seed]]s.{{sfn|Byng|2014}}{{sfn|Christenhusz et al|2017}}

== Taxonomy ==
Saxifragaceae has long been considered in a pivotal position in the evolution of angiosperm lineage, located in an ancestral "Saxifragalean stock". Historically the Saxifragaceae have included many very [[Morphology (biology)|morphologically]] disparate [[taxa]] in systems based on morphology alone, and has been very difficult to classify and characterize [[phenotypically]]. Consequently many different classifications have been published, differing considerably in both the relationship of the family to other angiosperms, and its internal structure, for instance the systems of [[Arthur Cronquist|Cronquist]] (1981), [[Rolf Dahlgren|Dahlgren]] (1983), [[Adolf Engler|Engler]] (1890), [[John Hutchinson (botanist)|Hutchinson]] (1973), Schulze-Menz (1964),{{sfn|Schulze-Menz|1964}} [[Takhtajan]] (1980) and [[Robert F Thorne|Thorne]] (1992) (''for a history, see {{harvtxt|Morgan|Soltis|1993}}''. In its broadest [[Circumscription (taxonomy)|circumscription]], it included 17 subfamilies.{{sfn|Schulze-Menz|1964}} This construction is referred to as Saxifragaceae ''[[sensu lato]]'' (''s.l.''). Within those subfamilies, the large majority of genera (30) were located within subfamily Saxifragoideae, the core group, with all but two of the remainder only having 1-3 genera.{{sfn|Morgan|Soltis|1993}}{{sfn|Soltis|Soltis|1997}}

The circumscription of the family has changed considerably in recent years, in large part due to [[molecular phylogenetic]] work showing the family ''s.l.'' to be [[polyphyletic]], and probably represents the most extreme example, with at least 10 evolutionary lines. Consequently the circumscription has been considerably reduced, with many of the subfamilies being either elevated to separate families, or placed as components of other families, often quite distant. For instance subfamily Parnassioideae was raised to the level of family [[Parnassiaceae]], and eventually a subfamily of [[Celastraceae]] (order [[Celastrales]]). Similarly the Hydrangoideae is now the family [[Hydrangeaceae]] (order [[Cornales]]).{{sfn|Morgan|Soltis|1993}}{{sfn|APG IV|2016}}

The reduced Saxifragaceae is distinguished by being referred to as Saxifragaceae ''sensu stricto'' (''s.s.''), corresponding to the Saxifragoideae a natural monophyletic group.{{sfn|Soltis et al|1993}} Historically, the Saxifragaceae has been placed in either the [[Order (biology)|order]]s [[Rosales]] or [[Saxifragales]]. This reduced Saxifragaceae, corresponding to subfamily Saxifragoideae and its 30 genera, is now placed within the Saxifragales. There, with three other subfamilies (Ribesoideaee, Iteoideae and Pterostemonoideae) it forms the Saxifragaceae alliance, while Penthoroideae and Tetracarpaeoideae are closely related within the core Saxifragales as shown in the [[cladogram]]. The remaining subfamilies are all transferred to more distant orders within the [[rosid]] and [[asterid]] clades.{{sfn|Deng et al|2015}}{{sfn|Morgan|Soltis|1993}}{{sfn|APG IV|2016}}
{{cladogram
|title= Cladogram I: Saxifragales families{{sfn|Jian et al|2008}}{{sfn|Stevens|2019}}{{sfn|APG IV|2016}}
|caption=100% [[maximum likelihood]] [[Bootstrapping (statistics)|bootstrap support]] except where labeled with bootstrap percentage<br/>Monogeneric families are represented by genus names, otherwise the number of genera is in (parentheses)<br/>[[Cynomorium]] (Cynomoriaceae) remains unplaced within this tree
|align=left
|cladogram=
{{clade | style=font-size:100%;line-height:120%;width:700px;
|label1=[[Saxifragales]]
|1={{clade
   |1=[[Peridiscaceae]] (4)
   |label2=97
   |2={{clade
      |label1=
      |1={{clade
         |1=''[[Peony|Paeonia]]'' (Paeoniaceae)
         |label2=woody clade
         |2={{clade
            |1=''[[Liquidambar]]'' (Altingiaceae)
            |label2=69
            |2={{clade
               |label1=98
               |1=[[Hamamelidaceae]] (27)
               |label2=95
               |2={{clade
                  |1=''[[Cercidiphyllum]]'' (Cercidiphyllaceae)
                  |2=''[[Daphniphyllum]]'' (Daphniphyllaceae)
                  }}
               }}
            }}
         }}
      |label2=core Saxifragales
      |2={{clade
         |1={{clade
            |1=[[Crassulaceae]] (34)
            |label2=Haloragaceae''s.l.''
            |2={{clade
               |1=''[[Aphanopetalum]]'' (Aphanopetalaceae)
               |2={{clade
                  |1=''[[Tetracarpaea]]'' (Tetracarpaeaceae)
                  |2={{clade
                     |1=''[[Penthorum]]'' (Penthoraceae)
                     |2=[[Haloragaceae]] ''s.s.'' (8)
                     }}
                  }}
               }}
            }}
         |label2=Saxifragaceae alliance
         |2={{clade
            |1={{clade
               |1=[[Iteaceae]] (including [[Pterostemonaceae]]) (2)
               }}
            |2={{clade
               |1=''[[Ribes]]'' (Grossulariaceae) 
               |2='''Saxifragaceae''' ''s.s.'' (33)
               }}
            }}
         }}
      }}
   }}
}}

}}

{{Clear}}

=== Subdivision ===
[[File:American Alumroot Heuchera americana 'Garnet' Stalk 2448px.JPG|thumb|upright|''[[Heuchera americana]]''|alt=Flower stalk of Heuchera americana]]
[[File:Rodgersia podophylla 4587.jpg|thumb|upright|''[[Rodgersia podophylla]]''|alt=Flowers of Rodgersia podophylla]]
[[File:Saxifraga merkii var idsuroei s2.jpg|thumb|upright|''[[Micranthes merkii]]''|alt=Flowers of Micranthes merkii]]

Numerous attempts have been made to subdivide Saxifragoideae (Saxifragaceae ''s.s.''). These have included dividing the family by the placentation of the ovules, as either parietal (e.g. ''Heuchera'') or axile (e.g. ''Saxifraga''). None of these has been supported by molecular data.{{sfn|Byng|2014}}{{sfn|Soltis et al|1993}}

[[molecular phylogenetic|Molecular data]] indicate that the family can be considered as a number of informal [[clades]], with two main lineages, saxifragoids and heucheroids and further subdivision of heucheroids into nine subclades or groups:{{sfn|Soltis et al|1993}}{{sfn|Deng et al|2015}}{{sfn|Byng|2014}}
;Clades (Genera (Species))
* Saxifragoids (''[[Saxifraga]]'' (370))
* Heucheroids (remaining genera):
** Leptarrhena (''[[Leptarrhena]]'' (1), ''[[Tanakaea]]'' (1))
** Saniculiphyllum (''[[Saniculiphyllum]]'' (1))
** Boykinia (''[[Boykinia]] (6), [[Bolandra]] (2), [[Hieronymusia]] (1), [[Jepsonia]] (3), [[Sullivantia]] (3), [[Suksdorfia]]'' (2), ''[[Telesonix]]'' (2))
** Astilbe (''[[Astilbe]]'' (23), ''[[Saxifragopsis]]'' (1))
** Heuchera ([[Heuchera]] (36), ''[[Bensoniella]] (1), [[Conimitella]] (1), [[Elmera]] (1), [[Lithophragma]] (10), [[Mitella]] (20), [[Tellima]] (1), [[Tiarella]]'' (3), ''[[Tolmiea]]'' (1))
** Cascadia (''[[Saxifraga|Cascadia]]'' (1), ''[[Saxifragodes]]'' (1))
** Darmera (''[[Darmera]] (1), [[Astilboides]] (1), [[Bergenia]] (10), [[Mukdenia]] (1), [[Oresitrophe]]'' (1), ''[[Rodgersia]]'' (5))
** Peltoboykinia (''[[Peltoboykinia]]'' (1), ''[[Chrysosplenium]]'' (55))
** Micranthes (''[[Micranthes]]'' (70))

The clades and subclades are related as shown in the cladogram:{{sfn|Deng et al|2015}}
{{cladogram|title=Cladogram II: Infrafamilial structure of Saxifragaceae
|caption=Diversification time in Mya underneath group names
|align=left
|cladogram=
{{clade|style=font-size:90%;line-height:100%
|label1='''Saxifragaceae'''
|sublabel1=38
|1={{clade
    |label1=Saxifragoids
    |sublabel1=30
    |1=''Saxifraga''
    |label2=Heucheroids
    |sublabel2=31
    |2={{clade 
      |1={{clade
     |sublabel1=20
        |1={{clade
          |sublabel1=18
          |1={{clade
             |sublabel1=8
             |1=Leptarrhena
             |sublabel2=16
             |2={{clade
               |1=''Saniculiphyllum''
               |sublabel2=11
               |2=Boykinia
                }}
             }}
             |sublabel2=14
             |2=Astilbe
             }}
         |2={{clade
          |1={{clade
           |sublabel1=7
           |1=Heuchera
           |sublabel2=29
           |2={{clade
           |1={{clade
                |sublabel1=19
                |1=Cascadia
                |sublabel2=10
                |2=Darmera
                }}
             |sublabel2=27
             |2={{clade
                |sublabel1=23
                |1=Peltoboykinia
                |sublabel2=15
                |2=''Micranthes''
                }}
           }}
}}
}}
}}
}} 
}}
}}
}}
{{Clear}}

==== Genera ====
{{main|List of Saxifragaceae genera}}
Saxifragaceae ''s.s.'' has about 33–35 genera and about 640 species. About half of the genera (18 of 33) are [[monotypic]], but ''Saxifraga'' has about 400 species, and has generally been divided into sections.{{sfn|Soltis et al|1993}}{{sfn|Christenhusz|Byng|2016}}{{sfn|Christenhusz et al|2017}}{{sfn|Deng et al|2015}}

=== Evolution and biogeography ===

The [[crown group]] of Saxifragaceae [[Genetic divergence|diversified]] at about 38&nbsp;[[Mya (unit)|Mya]] (Mid–Late [[Eocene]]), with the two main lineages diversifying arising at about 30&nbsp;Mya (Late Miocene/Early [[Oligocene]]). The present day heucheroid diversity dates later than the Miocene (''see sublabels in Cladogram II''). Ancestral Saxafragaceae emerged in either East Asia or Western North America, with subsequent dispersal West to Europe and south to South America. From the Eocene to the late Miocene these ancestral land masses were joined by the [[Bering Land Bridge]] facilitating plant migration.{{sfn|Deng et al|2015}}

=== Etymology ===

The family and type genus name are derived from the two Latin words ''saxum'' (rock), and ''frango'' (to break), but the exact origin is unknown, although surmised to refer to either growing in crevices in rocks or medicinal use for [[kidney stones]].{{sfn|Christenhusz et al|2017}}

== Distribution and habitat ==
[[File:Saxifragarufescens.jpg|thumb|231x231px|The native range of [[Saxifraga rufescens|''Saxifraga rufescens'']] is [[Tibet Autonomous Region|Tibet]], [[Sichuan]], [[Hubei|west Hubei]], [[Yunnan]] in [[China]] to [[Myanmar]]. In 2024, it was also recorded in [[Nagaland]] for the first time.]]
Primarily Northern hemisphere temperate and arctic regions, and also tropical montane, including the Americas, Europe, North Africa (including montane Ethiopia) and temperate and subtropical Asia to [[Luzon]] and New Guinea. In the Americas it extends south to central Mexico and the Andes to [[Tierra del Fuego]]. [[Centres of diversity]] are western N America, East Asia and the Himalayas. The largest concentration of genera are in the Pacific North West. Some ''Saxifraga'' and ''Chrysosplenium'' are [[circumboreal]]. Others have [[disjunct distributions]] between E Asia and N America, while other taxa have separate narrow distributions in southern S America. Some species are found in wet woodlands, swamplike conditions and wet cliff edges.{{sfn|Christenhusz et al|2017}}{{sfn|Deng et al|2015}}{{sfn|Byng|2014}}

== References ==
{{Reflist|20em}}

== Bibliography ==
{{Refbegin|30em}}

=== Books ===

* {{cite book|last1=Byng|first1=James W.|author-link=James W. Byng|title=The Flowering Plants Handbook: A practical guide to families and genera of the world|date=2014|publisher=Plant Gateway Ltd.|isbn=978-0-9929993-1-5|url=https://books.google.com/books?id=yoLaBAAAQBAJ|chapter=Saxifragales|pages=156–166}}
* {{cite book|last1=Christenhusz|first1=Maarten J. M.|last2=Fay|first2=Michael F.|last3=Chase|first3=Mark W.|author-link1=Maarten Christenhusz|author-link2=Michael F. Fay|author-link3=Mark W. Chase|title=Plants of the World: An Illustrated Encyclopedia of Vascular Plants|url=https://books.google.com/books?id=LLo7DwAAQBAJ|date= 2017|publisher=[[University of Chicago Press]]|isbn=978-0-226-52292-0|chapter=Saxifragales|pages=231–244|ref={{harvid|Christenhusz et al|2017}}}}
* {{cite book |editor-first=Klaus |editor-last=Kubitzki |editor-link=Klaus Kubitzki |title=Flowering Plants. Eudicots: Berberidopsidales, Buxales, Crossosomatales, Fabales p.p., Geraniales, Gunnerales, Myrtales p.p., Proteales, Saxifragales, Vitales, Zygophyllales, Clusiaceae Alliance, Passifloraceae Alliance, Dilleniaceae, Huaceae, Picramniaceae, Sabiaceae |series=The Families and Genera of Vascular Plants |url=https://books.google.com/books?id=PdSL7jBNX9EC |date=2007 |publisher=Springer  |volume=IX |isbn=978-3-540-32219-1 |chapter=Introduction to Saxifragales|pages=15–18}}
** {{cite book |first=D E |last=Soltis |author-link=Douglas Soltis|title=Saxifragaceae |url=https://www.researchgate.net/publication/262006159|pages=418–435|date=2007}}, in {{harvtxt|Kubitzki|2007}}
* {{cite book |editor1-last=Melchior |editor1-first=Hans |editor-link1=Hans Melchior|editor2-last=Werdermann |editor2-first=E |title=A. Engler's Syllabus der Pflanzenfamilien: mit besonderer Berücksichtigung der Nutzpflanzen nebst einer Übersicht über die Florenreiche und Florengebiete der Erde. (2 vols.) |date=1964 |publisher=[[Gebrüder Borntraeger Verlag]] |location=Berlin |edition=12th|last=Schulze-Menz|first=G K|chapter=Saxifragaceae|pages=201–206}} ''(see also [[Syllabus der Pflanzenfamilien]])''

=== Articles ===

* {{Cite journal |author=Angiosperm Phylogeny Group IV|author-link=Angiosperm Phylogeny Group|year=2016 |title=An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV |journal=[[Botanical Journal of the Linnean Society]] |volume=181 |issue=1 |pages=1–20  |doi=10.1111/boj.12385|ref={{harvid|APG IV|2016}} |doi-access=free }}
* {{cite journal |last1=Christenhusz|first1=Maarten JM|last2=Byng|first2= J. W.  |author-link1=Maarten Christenhusz|author-link2=James W. Byng|name-list-style=amp | year = 2016 | title = The number of known plants species in the world and its annual increase | journal = [[Phytotaxa]] | volume = 261 | pages = 201–217 | url = http://biotaxa.org/Phytotaxa/article/download/phytotaxa.261.3.1/20598 | doi = 10.11646/phytotaxa.261.3.1 | issue = 3 | publisher = Magnolia Press | doi-access = free }}
* {{cite journal |last1=Deng |first1=Jia-bin |last2=Drew |first2=Bryan T. |last3=Mavrodiev |first3=Evgeny V. |last4=Gitzendanner |first4=Matthew A. |last5=Soltis |first5=Pamela S. |last6=Soltis |first6=Douglas E.|author-link5=Pamela S. Soltis |author-link6 = Douglas E. Soltis |title=Phylogeny, divergence times, and historical biogeography of the angiosperm family Saxifragaceae |url=https://www.researchgate.net/publication/269188706|journal=[[Molecular Phylogenetics and Evolution]] |date=February 2015 |volume=83 |pages=86–98 |doi=10.1016/j.ympev.2014.11.011|pmid=25479063 |ref={{harvid|Deng et al|2015}}}}
* {{cite journal |last1=Jian|first1=Shuguang  |author2-link=Pamela S. Soltis |first2=Pamela S. |last2=Soltis |first3=Matthew A. |last3=Gitzendanner |first4=Michael J. |last4=Moore |first5=Ruiqi |last5=Li |first6=Tory A. |last6=Hendry |first7=Yin-Long |last7=Qiu |first8=Amit |last8=Dhingra |first9=Charles D. |last9=Bell |author10-link=Douglas E. Soltis |first10=Douglas E. |last10=Soltis
|doi=10.1080/10635150801888871 | pmid =18275001 | volume=57 | issue=1 | title=Resolving an ancient, rapid radiation in Saxifragales | date=February 2008 | pages=38–57 | journal=[[Systematic Biology]] |ref={{harvid|Jian et al|2008}}|doi-access=free }}
* {{cite journal |last1=Morgan |first1=David R. |last2=Soltis |first2=Douglas E. |author-link2 = Douglas E. Soltis |title=Phylogenetic Relationships Among Members of Saxifragaceae Sensu Lato Based on rbcL Sequence Data |journal=[[Annals of the Missouri Botanical Garden]] |date=1993 |volume=80 |issue=3 |pages=631 |doi=10.2307/2399851|jstor=2399851 }}
* {{cite journal |last1=Soltis |first1=Douglas E. |last2=Soltis |first2=Pamela S. |author-link1=Douglas Soltis|author-link2=Pamela Soltis|title=Phylogenetic relationships in Saxifragaceae sensu lato: a comparison of topologies based on 18S rDNA and rbcL sequences |journal=[[American Journal of Botany]] |date=April 1997 |volume=84 |issue=4 |pages=504–522 |doi=10.2307/2446027|jstor=2446027 |pmid=21708603|doi-access=free }}
* {{cite journal |last1=Soltis |first1=Douglas E. |last2=Morgan |first2=David R. |last3=Grable |first3=Albert |last4=Soltis |first4=Pamela S. |last5=Kuzoff |first5=Robert |author-link1=Douglas Soltis|author-link4=Pamela Soltis|title=Molecular Systematics of Saxifragaceae Sensu Stricto |journal=[[American Journal of Botany]] |date=September 1993 |volume=80 |issue=9 |pages=1056 |doi=10.2307/2445753|jstor=2445753 |ref={{harvid|Soltis et al|1993}}}}

=== Websites ===

* {{cite web |last=Stevens |first=P.F. |author-link=Peter F. Stevens|date=2019|orig-year= 2001 |title= Saxifragales|website=[[Angiosperm Phylogeny Website|AP Web v. 14]]|publisher=[[Missouri Botanical Garden]]|url=http://www.mobot.org/MOBOT/Research/APweb/orders/saxifragalesweb.htm#Saxifragales|access-date=25 September 2019}} (''see also'' [[Angiosperm Phylogeny Website]])
* {{cite web |last=POWO|author-link=Plants of the World Online|title= Saxifragaceae Juss.|url= https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30001425-2|website=Plants of the World Online |publisher=[[Royal Botanic Gardens, Kew]]| date=2019|access-date=1 December 2019 }}
{{Refend}}

==External links==
{{Wikispecies|Saxifragaceae }}
*{{Commons category-inline|Saxifragaceae}}
*{{cite EB1911|wstitle=Saxifragaceae |volume=24 |short=x}}
*[http://www.topwalks.net/plants/generos/saxifragaceae_01.htm Saxifragaceae in Topwalks]

{{Angiosperm families}}
{{Taxonbar|from=Q2543932}}
{{Authority control}}

[[Category:Saxifragaceae| ]]
[[Category:Saxifragales families]]