Classification System: APG IV
Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Ordo: Saxifragales
Familia: Crassulaceae
Subfamiliae: Crassuloideae – Kalanchoideae – Sempervivoideae
Genera: Adromischus – Aeonium – Afrovivella – Aichryson – Bryophyllum – Chiastophyllum – Cotyledon – Crassula – Cremnophila – Diamorpha – Dudleya – Echeveria – Graptopetalum – Greenovia – Hylotelephium – Hypagophytum – Jovibarba – Kalanchoe – Lenophyllum – Meterostachys – Monanthes – Mucizonia – Ohbaea – Orostachys – Pachyphytum – Perrierosedum – Petrosedum – Phedimus – Pistorinia – Prometheum – Pseudosedum – Rhodiola – Rosularia – Sedella – Sedum – Sempervivum – Sinocrassula – Thompsonella – Tylecodon – Umbilicus – Villadia
Name
Crassulaceae J.St.-Hil. (1805), nom. cons.
Type genus: Crassula L.
Synonyms
Heterotypic
Cotyledonaceae Martinov, Tekhno-Bot. Slovar: 168 (1820).
Type genus: Cotyledon L.
Rhodiolaceae Martinov, Tekhno-Bot. Slovar: 546 (1820).
Type genus: Rhodiola L.
Sedaceae Roussel, Fl. Calvados, ed. 2: 291 (1806).
Type genus: Sedum L.
Sempervivaceae Juss., Gen. Pl.: 207 (1789).
Type genus: Sempervivum L.
Note: This is a view of Crassulaceae s.l. (Hassler et al., 2019 & Thiede & Eggli, 2007) c.f. Govaerts et al. (2019) for an opinion of Crassulaceae s.s. with fewer segregates from Sedum. Differences of opinion involve the highly paraphyletic nature of the species rich Sedum, which can make generic circumscriptions difficult particularly in Sedeae, Klein in Kadereit et al. (2016) presents a synopsis. There is little consensus so WS must maintain a conservative approach until the situation becomes clearer.
References
Saint-Hilaire, J.H.J. 1805. Exposition des Familles Naturelles 2: 123.
Gontcharova, S.B. & Gontcharov, A.A. 2009. Molecular phylogeny and systematics of flowering plants of the family Crassulaceae DC. Molecular Biology 43(5): 794. DOI: 10.1134/S0026893309050112 PDF from ResearchGate Reference page.
Govaerts, R. et al. 2019. Crassulaceae in Kew Science Plants of the World online. The Board of Trustees of the Royal Botanic Gardens, Kew. Published online. Accessed: 2019 Aug. 30. Reference page.
Hassler, M. 2019. Crassulaceae. World Plants: Synonymic Checklists of the Vascular Plants of the World In: Roskovh, Y., Abucay, L., Orrell, T., Nicolson, D., Bailly, N., Kirk, P., Bourgoin, T., DeWalt, R.E., Decock, W., De Wever, A., Nieukerken, E. van, Zarucchi, J. & Penev, L., eds. 2019. Species 2000 & ITIS Catalogue of Life. Published online. Accessed: 2019 Aug. 26 {{{3}}}. Reference page.
International Plant Names Index. 2019. 26. Published online. Accessed: Aug. 2019.
Kadereit, J.W., Albach, D.C., Ehrendorfer, F., Galbany Casals, M., Garcia-Jacas, N., Gehrke, B., Kadereit, G., Kilian, N., Klein, J.T., Koch, M.A., Kropf, M., Oberprieler, C., Pirie, M.D., Ritz, C.M., Röser, M., Spalik, K., Susanna, A., Weigend, M., Welk, E., Wesche, K., Zhang, L.-B. & Dillenberger, M.S. 2016. Which changes are needed to render all genera of the German flora monophyletic? Willdenowia 46(1): 39–91. DOI: 10.3372/wi.46.46105 PDF Reference page. See Klein p. 48.
Mort, M.E., O’Leary, T.R., Carrillo-Reyes, P., Nowell, T., Archibald, J.K. & Randle, C.P. 2010. Phylogeny and evolution of Crassulaceae: past, present, and future. Schumannia 6: 69-86. PDF from ResearchGate Reference page.
Nikulin, A.Y., Nikulin V.Y. & Gontcharov A.A. 2015. On the Phylogenetic Structure of the Tribe Telephieae (Sempervivoideae, Crassulaceae) on the Base of rDNA Sequence Comparisons. Ботанический Журнал (Botanicheskii Zhurnal) 100(10):1030–1040. . (in Russian) DOI: 10.1134/S0006813615100038 PDF from ResearchGate Reference page.
Nikulin, V.Y., Gontcharova, S.B., Stephenson, R. & Gontcharov, A.A. 2016. Phylogenetic relationships between Sedum L. and related genera (Crassulaceae) based on ITS rDNA sequence comparisons. Flora 224: 218-229. DOI: 10.1016/j.flora.2016.08.003 PDF Reference page.
Nikulin, V.Yu. & Goncharov, A.A. 2017. Molecular and phylogenetic characteristics of Sedum (Crassulaceae) and related genera based on a comparison of the nucleotide sequences of the matK gene of chloroplast DNA and the ITS of the ribosomal DNA region. Botanical Journal 102 (3): 309-328. PDF from ResearchGate In Russian, abstract in English. Reference page.
Shaw, J.M. 2017. (2512) Proposal to conserve the name Orostachys with a conserved type (Crassulaceae). Taxon 66(2): 521-522. DOI: 10.12705/662.24 Reference page.
Thiede, J. & Eggli, U. 2007. Crassulaceae in Kubitzki, K., Bayer, C. & Stevens, P.F. (Eds.) 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 pp. 83–119 DOI: 10.1007/978-3-540-32219-1_12 ISBN 3540322140 Crassulaceae PDF in Research Gate Reference page.
Stevens, P.F. 2001 onwards. Angiosperm Phylogeny Website. Version 14, July 2017 [and more or less continuously updated since]. Online. Reference page.
Tropicos.org 2019. Crassulaceae. Missouri Botanical Garden. Published online. Accessed: 26 Aug. 2019.
Vernacular names
Afrikaans: Vetkruidfamilie
aragonés: Crasulacias
العربية: مخلدية
asturianu: Crasulácees
azərbaycanca: Dovşankələmikimilər
беларуская: Таўсцянкавыя
български: Дебелецови
català: Crassulàcies
čeština: Tlusticovité
dansk: Stenurt-familien
Deutsch: Dickblattgewächse
English: Stonecrop family, Orpine family
Esperanto: Krasulacoj
español: Crasuláceas
eesti: Paksulehelised
euskara: Krasulazeoak
فارسی: گلنازیان
suomi: Maksaruohokasvit
עברית: טבוריתיים
hrvatski: Tustikovke
hornjoserbsce: Tučnołopjenakowe rostliny
magyar: Varjúhájfélék
italiano: Crassulacee
日本語: ベンケイソウ科
ქართული: მსუქანასებრნი
қазақша: Жасаңшөптер тұқымдасы
ಕನ್ನಡ: ಗಂಡು ಕಾಳಿಂಗ
한국어: 돌나물과
lietuvių: Storlapiniai
latviešu: Biezlapju dzimta
മലയാളം: ക്രാസ്സുലേസീ
मराठी: हेमसागर
Nederlands: Vetplantenfamilie
norsk nynorsk: Bergknappfamilien
norsk: Bergknappfamilien
polski: Gruboszowate
پنجابی: موٹے پتر
Runa Simi: Pirqakachun yura rikch'aq ayllu
русский: Толстянковые
slovenčina: Tučnolistovité
slovenščina: Tolstičevke
српски / srpski: Жедњаци
svenska: Fetbladsväxter
ไทย: วงศ์กุหลาบหิน
Türkçe: Damkoruğugiller
українська: Товстолисті
Tiếng Việt: Họ Lá bỏng
中文: 景天科
The Crassulaceae (from Latin crassus, thick), also known as the stonecrop family or the orpine family, are a diverse family of dicotyledon flowering plants characterized by succulent leaves and a unique form of photosynthesis, known as Crassulacean acid metabolism (CAM). Flowers generally have five floral parts. Crassulaceae are usually herbaceous but there are some subshrubs, and relatively few treelike or aquatic plants. Crassulaceae are a medium size monophyletic family in the core eudicots, among the order Saxifragales, whose diversity has made infrafamilial classification very difficult. The family includes approximately 1,400 species and 34–35 genera, depending on the circumscription of the genus Sedum, and distributed over three subfamilies. Members of the Crassulaceae are found worldwide, but mostly in the Northern Hemisphere and southern Africa, typically in dry and/or cold areas where water may be scarce, although a few are aquatic.
Crassulaceae are mainly perennial and have economic importance as garden plants. Many members have a bizarre, intriguing appearance, and are quite hardy, typically needing only minimal care. Familiar species include Crassula ovata (jade plant or friendship tree), Kalanchoe blossfeldiana (florists' kalanchoe), Sempervivum (houseleek or hen and chicks), Monanthes, Umbilicus (pennywort), Bryophyllum, Echeveria and Cotyledon.
Description
Morphology
Rosetted succulent leaves of Aeonium arboreum
Aeonium arboreum (Aeonieae): Succulent leaves in rosettes
Corolla tubes in Kalanchoe pinnata flower
Kalanchoe pinnata (Kalanchoöideae): Corolla tubes
Apopetaly, actinomorphy, polymery, with stamens in 2 whorls, in Sempervivum
Sempervivum sp. (Sempervivoideae): Apopetaly, actinomorphy, polymery, stamens in 2 whorls
General: Crassulaceae is a family of morphologically diverse terrestrial perennial, rarely annual or hapaxanthic (flowering once in a lifetime), flowering plants that demonstrate xerophytic adaptations, with thick succulent leaves, a thick waxy cuticle and Crassulacean acid metabolism. Crassulaceae are generally herbaceous but there are some subshrubs, and relatively few treelike, epiphytic (growing on surface of plants), scandent (vine like) or aquatic plants.[3][4] Most species are herbaceous leaf succulents, with regular 5 part (pentamerous or fivemerous) flowers, isomerous free carpels and one or two whorls of stamens.[5]
Vegetative: Stems are sometimes succulent, as may also be the underground caudices (rootstock), and may form rhizomes or corms. Bulbils may form along the stem or leaf margins. The leaf arrangement is opposite and decussate or alternate and spiral, and they are frequently aggregated into rosettes. The leaf shape is simple (rarely pinnate) and usually entire, or crenate to broadly lobed, sometimes dentate or more deeply incised, glabrous (smooth) or tomentose. In cross section the leaf blades are flat or round. They may be sessile or petiolate. Stipules are absent. New plants often form easily from vegetative parts that fall off the parent plant.[6][7]
Reproductive: The inflorescence is usually terminal to lateral with many-flowered thyrses of cymes, less commonly spikes, racemes or panicles, rarely few to single flowered and axillary. The inflorescence is often many-branched and bracteate. The flower clusters are red, yellow, or white.[8][7][6]
The flowers are often apopetalous (separate corolla segments), pentamerous (five-parted), actinomorphic (radially symmetrical), except for the zygomorphic Tylecodon grandiflorus, with one to two whorls of 4–20 sepals that are usually as many as or twice as many as the number of petals and two whorls of stamens, five in each whorl (i.e. as many as or twice the number of petals), with their filaments either free or fused to the petals at the base and sometimes unequal. Anthers are basifixed and open lengthwise. The flowers are bisexual, less commonly unisexual (more or less dioecious).[6] Ovaries superior to partially inferior, with carpels equal to the number of petals, each forming a single locule, superior, free or almost so, basally with a small to conspicuous basal nectary scale, gradually tapering to a short to long style with few to many ovules. The fruit is usually capsular with dehiscent follicles, opening along the carpal suture and many seeded. The seeds are small (1.5–3 mm), smooth, elongate, papillate to longitudinally ridged, and generally brownish.[6][7][9][10]
However, a number of genera (e.g. Sempervivum, Aeonium) are polymerous (3-32), have basally fused or partially fused corolla segments, where the petals may form a corolla tube of varying length (e.g. Kalanchoe, Cotyledon), or have only a single whorl of 5 stamens (e.g. Crassula, Tillaea),[11] while Sedum includes much of the morphological diversity within the family as a whole.[9] Although the typical number of floral plants is four or five, a number of genera, such as Sempervivum and Jovibarba, demonstrate polymery (at least ten or greater parts).[9]
Genome
Chromosome numbers are highly variable. The original base chromosome number is x=8, decreasing to 7 in Crassula. In Sedoideae, the base number increases to 9 in the Kalanchoe clade, but Kalanchoe have x=17 or 18 (or a multiple),and is probably of polyploid origin, derived from a tetraploid Cotyledon like taxon. In the Telephium sensu Hart clade the base number has increased to 12 and higher. Of the subclades within Telephium, the first (Hylotelephium sensu Thiede & Eggli: Hylotelphium, Orostachys and Sinocrassula) has x=12, and of the Rhodiola clade Phedimus has x=16 and Umbilcus x=24, representing another episode of polyploidy. Within Sempervivum, Sedum series Rupestre (Petrosedum) has x=28. Within the Leucosedum, most taxa are diploid, with 2x=12, 14 but includes two subclades, one with x=6 or 7, the other x=6, but a few have 14 or 16. Acre includes a wide variety of chromosome numbers from x=6 to 270, and occasionally larger and displays widespread polyploidy. Aeonium includes some Sedum species with x=8, while the remaining taxa are x=18. The core of this clade is probably polyploid from an ancestor with x=8.[9]
Phytochemistry
Crassulacean acid metabolism (CAM photosynthesis) is named after the family, because the pathway was first discovered in crassulacean plants. It is one of the few families that still has CAM as an active, photosynthetic pathway, and is unique in which all its members are known to possess CAM.[3]
Taxonomy
Originally described by Saint-Hilaire (1805) as Crassuleae,[12] and therefore has his name as the botanical authority.[1] Authority has also, at times, been given to De Candolle (DC),[3] who first used the term "Crassulaceae" in 1815.[13] He later placed the family among the Dicotyledons.[14]
One of the most complete treatments was Alwin Berger's revision in 1930.[15][5][16] At that time the family comprised about 1,500 species, distributed over six subfamilies and 33 genera. Circumscription of the family has remained relatively stable, with the exception of the placement of the genus Penthorum, which has at times been placed either in its own monogeneric family, Penthoraceae, or in the Saxifragaceae. When Penthorum was separated from Crassulaceae, the latter became a natural monophyletic group.[17][18][19] Some later authors, such as Cronquist, included only 900 species.[20][21] Thiede and Eggli (2007), in their treatment of the family, describe 34 genera with about 1,410 species.[3] The size of the genera varies considerably, from Sedum, the largest with 300–500 species, to the smallest, which are monotypic.[2] Estimates of the number of species has varied between 1500 (Berger 1930)[15] and 900 (Cronquist 1981).[20][5]
Molecular phylogenetics has shown that morphological characters and chromosome numbers are so labile in the family, with rampant polyploidy and aneuploidy, that they cannot be used reliably to infer evolution, even at low taxonomic levels, with few exceptions. For instance Prometheum and Rosularia have been segregated from Sedum by their basic chromosome numbers.[4][5][18]
Crassulaceae is a medium size monophyletic grouping[19] within the core eudicots. Originally considered a primitive member of the Rosidae,[5] in the order Saxifragales, it is now placed, with that order as a superrosid under the classification system of the Angiosperm Phylogeny Group. There, the Saxifragales are a sister group to the rosids.[1][18] Classification within the family is difficult and complex because many of the species hybridize readily, both in the wild and in cultivation, and the family is morphologically, cytologically and geographically diverse. As a result, generic boundaries have been considered unclear with frequent intergradation of characteristics between taxa, which may represent recurrent adaptation to xeric habitats.[9]
Phylogeny
Crassulaceae has been considered a part of the order Saxifragales by most modern authors, including Cronquist (1981),[20] Takhtajan (1987),[22] and Thorne (1992),[23] based on phenotypic features, but subsequently confirmed by molecular methods.[10] The place of Crassulaceae within Saxifragales has varied over time, as molecular data accumulates. The number of families within Saxifragales varies depending on the delimitation of individual families. Here, 14 families are shown in a cladogram, according to the Angiosperm Phylogeny Website, situating Crassulaceae as sister to the Haloragaceae sensu lato, and thus forming one of two subclades of the core Saxifragales.[24][1]
Cladogram of Saxifragales showing the evolutionary affinities of Crassulaceae
|
This phylogenetic tree has been reconstructed with two different methods (maximum likelihood and Bayesian inference) from ca. 50,000 molecular characters, including plastid DNA, mitochondrial DNA, and nuclear DNA sequences.[25] Monogeneric families are represented by genus names, with family in parentheses. Unless otherwise stated, support for most nodes is maximal and equal to 100%.
Biogeography and evolution
Crassulaceae evolved approximately 100–60 million years ago in southern Africa with the two most basal phylogenetic branches (Crassula, Kalanchoe) representing the predominantly southern African members.[19][3] Other sources suggest that Crassulaceae evolved approximately 70 million years ago together with Haloragaceae sensu lato (Penthoraceae, Haloragaceae).[18] The family is considered to have had a gradual evolution, with a basal split between Crassuloideae and the rest of the family (Kalanchoideae, Sempervivoideae). The Sempervivoideae subsequently dispersed north to the Mediterranean region, and from there to Eastern Europe and Asia (Sempervivum and Leucosedum clades), with multiple groups spreading over the three continents of the Northern Hemisphere. Two lineages from the European Crassulaceae eventually dispersed to North America and underwent subsequent diversification. The Aeonium clade dispersed from northern Africa to adjacent Macaronesia.[9]
Distinct centers of speciation developed in Macaronesia (Aeonium clade), Mexico (Sedum and Echeverioideae in clade 7), and southeastern Asia (Sedum sarmentosum, and S. morissonensis in Acre clade). On arrival in the Northern hemisphere the Sempervivoideae reached its greatest diversity. Conversely, few representatives of the Crassulaceae occur in South America and Australia.[5][9] Sedum species are found in most of these regions, generally grouped with genera endemic to that region. For instance the North African S. jaccardianum and S. modestum (Aeonium) are a sister group to the endemic Macaronesian species in that clade.[9] The Macaronesian archipelago appears to have been reached by Crassulaceae at least three times. Once by the ancestor of Aeonium and Monanthes, most likely from the Western Mediterranean region, with the closest extant relatives of these two genera (Sedum caeruleum, S. pubescens), coming from this region (Aeonium clade). The second migration was by an ancestor of a clade of three Sedum species (S. nudum, S. lancerotense and S. fusiforme (Acre clade)), which appear to have originated in Mexico. The third occurrence likely involved the ancestor of a lineage within the genus Umbilicus (Rhodiola clade). The Macronesian flora include three genera from the Sepervivoideae, Aeonium, Aichryson and Monanthes (Aeonium clade), together with several Sedum spp. and one species of Umbilicus (Rhodiola). North America was reached at least twice, once by an ancestor of Parvisedum and Dudleya, and once by a subclade of Acre. For a mapping of morphological features and biogeography on the phylogenetic tree, see Mort et al 2001 Fig. 3.[5][9]
Chromosome numbers have played a limited role in elucidating evolution, but suggest a core of x=8, with subsequent polyploidy. For a mapping of chromosome numbers on the phylogenetic tree, see Mort et al 2001 Fig. 4.
Subdivision
History
When Carl Linnaeus published his Species Plantarum in 1753[26] only a few genera, included in the modern circumscription of Crassulaceae were described; the type genus Crassula (10 species), Tillaea (3), Cotyledon (6), Sempervivum (6), Rhodiola (1) and Sedum (15). By 1777, Rhodiola had been submerged into Sedum, only to be separated again in the twentieth century.[27]
While the family can fairly easily be recognised, identifying its constituent genera has been far more problematic.[5] For an extensive history of subfamily Sedoideae, see Ohba 1978. Saint-Hilaire's original description in 1805 included seven genera,[12] as did De Candolle (1815).[13] In a much more extensive treatment in 1828, he divided the Crassulaceae into the two groups, Isostemonae and Diplostemonae (i.e. haplostemony vs. obdiplostemony) on the basis of the number of staminal whorls. The former corresponded to the modern Crassuloideae.[14][5] Two lineages, six subfamilies, and 33 genera of Crassulaceae were described by Berger in 1930:[15]
Lineages, subfamilies, biogeography, No. genera, type genus (No. species in genus)
Crassula (Southern hemisphere)
Crassuloideae S Africa 5 Crassula (300)
(Crassula, Dinacria, Rochea, Vauanthes, Pagella)
Kalanchiodeae S Africa, Madagascar 3 Kalanchoe (200)
(Kalanchöe, Bryophyllum, Kitchingia)
Cotyledonoideae S Africa, Mediterranean 6 Cotyledon (30)
(Cotyledon, Adromischus, Umbilicus, Chiastophyllum, Pistorina, Mucizonia)
Sedum (Northern hemisphere)
Echeveroideae Mexico 5 Echeveria (150)
(Echeveria, Villadia, Altamiranoa, Pachyphytum, Lenophyllum)
Sempervivoideae Mediterranea, Macaronesia 5 Sempervivum (25)
(Sempervivum, Aeonium, Greenovia, Monanthes, Aichryson)
Sedoideae N hemisphere, S America, N & E Africa 11 Sedum (500)
(Sedum, Rosularia, Orostachys, Diamorpha, Pseudosedum, Hypagophytum, Afrovivella, Sempervivella, Sinocrassula)
Each of these contained one of the largest genera.[2] Though various revisions since have proposed simpler schemes, such as Borisova (1939, revised 1969).[28][29] Berger's classification has proven practical and been the most widely used,[18] although some of the subfamilies are polyphyletic.[5] Berger's classification depended on biogeography and a number of morphological characteristics (primarily the number and arrangement of floral parts (haplostemonous androecia, polymery), the degree of sympetaly, and phyllotaxis)[4] which are now recognized as being of limited value due to extensive homoplasy, having evolved independently many times, and hence provides little useful information, only two of the subfamilies proving monophyletic.[3] Berger used sympetaly to define the group of Kalanchiodeae, Cotyledonoideae and Echeveroideae, but it also occurs in taxa within Crassuloideae and Sedoideae. Berger also placed all species with polymery into his Sempervivoideae, but it occurs in two different clades, Sempervivum and Aeonium.[9] Although five of his six subfamilies appeared to be morphologically and geographically defined,[10] the Sedoideae were problematic, being an artificial construction containing all taxa which could not be fitted into the other subfamilies (catch-all).[5]
Sedoideae contained three centres of diversity, East Asia, the Mediterranean region and North America, with the greatest in E. Asia. Only a few taxa, such as Rhodiola and Hylotelephium, occurring in all three regions. About 120 species were found in Europe and adjacent parts of North Africa and West Asia,[30] and 400 in Eastern and central Asia.[31]
Within Sedoideae, the large cosmopolitan typical genus Sedum (ca. 500 species), accounts for much of these issues, together with several smaller genera. Sedum refers to herbaceous, predominantly perennial species with alternate and entire leaves, a single subaxial hydathode and pentamerous obdiplostemous flowers with free petals. Most systematic treatments of the genus have resulted in conflicting classifications and evolutionary relationships within the Sedoideae.[5] Attempts to resolve this have followed two opposing positions, lumping and splitting. Either accepting one artificial large catch-all polyphyletic genus, sensu lato (Sedum s.l.), or splitting it into many smaller genera, sensu stricto (Sedum s.l.). In the 1930s, Berger represented the splitting school of thought segregating genera such as Orostachys, Rosularia, Pseudosedum and Sempervivella.[15] In contrast, Fröderströmm[32] favoured retaining a broader construct of Sedum, recognising only Pseudosedum.[27] In more recent times Ohba (1978) proposed the narrower view,[27] segregating Rhodiola, Hylotelephium and Prometheum, among other genera.[4][18] Ohba then subdivided the old world taxa of his now reduced Sedum into five subgenera:[30][27]
subgenus Aizoon
subgenus Balfouria
subgenus Spathulata
subgenus Sedum
subgenus Telmissa
Grulich (1984) continued this process, proposing Aizopsis (subgenus Aizoon), Asterosedum (subgenus Spathulata), Petrosedum (subgenus Sedum series Rupestria) and Oreosedum (subgenus Sedum series Alba) as separate genera.[30] As many as 32 segregate genera have been published, and most Eurasian crassulacean species were originally included in Sedum, but subsequently segregated (see Sempervivoideae).[33][17]
Subsequently, various revisions have proposed fewer subfamilies. Takhtajan (1987) initially submerged Sempervivoideae in Sedoideae and Cotyledonoideae in Kalanchiodeae to produce four,[22] but later (1997) only three, Crassuloideae, Kalanchoideae and Sedoideae. Thorne (1992) also proposed three (Sedoidea, Cotyledonoidea, Crassuloidea), [23] and then two (2000), Crassuloideae and Sempervivoideae.[34]
Molecular phylogenetics
Prior to the use of molecular methods of classification, attempts to replace Berger's system were largely unsuccessful.[17] Subsequently, Hart and colleagues[a] (1995) proposed two subfamilies, based on molecular phylogenetic data with chloroplast DNA, based on 49 species in 26 genera, which identified seven clades, named for constituent genera or species.[10] Hart utilized a hierarchical system of subfamilies, tribes and subtribes, based on molecular, geographical and morphological criteria, including embryology, pollen morphology and phytochemistry.[2]
Subfamily Crassuloideae Berger Type: Crassula 2 South African genera (250 species)
Subfamily Sedoideae Berger Type: Sedum
Tribe Kalanchoeae 't Hart Type: Kalanchoe 5 S African genera (250 spp.)
Tribe Sedeae 't Hart Type: Sedum
Subtribe Telephiinae 't Hart Type: Hylotelephium 8 Asian genera (150 spp.)
Subtribe Sedinae 't Hart Type: Sedum 18 Northern hemisphere genera (700 spp.)
The basal split at subfamily level, separates the haplostemonous (single series of stamens, equal in number to petals) African Crassuloideae with opposite leaves, from the Sedeae without these characteristics (obdiplostemonous, two whorls of stamens, twice as many as petals).[2]
These clades were (1–7):
Crassula/Crassuloideae, the basal divergence, corresponds to Berger's subfamily of that name and are haplostemonous, but this feature is homoplasious. Confined to southern Africa, except for aquatic species, which are cosmopolitan.[10]
Kalanchoe/Kalanchoeae, the second divergence, corresponds to Berger's Kalanchoideae (Kalanchoe, Bryophyllum, Kitchingia) and the 2 S. African members of Cotyledonoideae (Adromischus, Cotyledon), together with Tylecodon which was segregated from Cotyledon in 1978.[35] It was characterized by 4- or 5-merous flowers, connate petals and seeds, together with leaves that are flat, crenate or dentate (toothed), often petiolate and decussate. Chromosome number x=9. Within the clade, Adromischus forms the basal divergence, followed by Cotyledon/Tylecodon as sister to Kalanchoe.[10]
Telephium/Telephiinae include members of Cotyledonoideae (Umbilicus), together with some Sedoideae genera (including Hylotelephium) and two of Ohba's five subgenera of Sedum (Aizoon and Spathulata)[31] and are usually obdiplostemonous, 5-merous flowers with free petals, flat and often crenate or dentate leaves ("flat leaved Asian Sedum") and have tubers, tuberous roots or woody or thickened rhizomes (monopodial or sympodial). In this respect many species share leaf features with the Kalanchoeae and Hart considered that the Telephiinae "bridge the gap" between the African Kalanchoeae and the Northern hemisphere Sedinae. Distribution predominantly East Asia, with Umbilicus being Mediterranean.[10]
Sempervivum includes the montane/alpine Eurasian Sempervivum, its nominative genus, together with Sedum from the same region, including Sedum series Rupestria. Sempervivum is closely related to Jovibarba, which some authors place within the former genus.[10]
Leucosedum, i.e. "White Sedum", from Sedum album, is polygeneric and includes additional Cotyledonoideae and Eurasian Sedoideae, including Sedum album and other species of Sedum subgenus Gormania. The other genera are thought to have evolved from the Sedum lineage in this clade, including Dudleya and Sedella (N America) and Rosularia, Prometheum and Pistorina (Eurasia). This grouping of 5–7 genera accounts for about 200 species. Some Sedum subgenus Sedum species also place here. Leucosedum species are found throughout the arid southwest United States and Mexico, as well as Eurasia.[9][10]
Aeonium is predominantly Macaronesian Sempervivoideae (Aeonium, Aichryson, Greenovia and Monanthes), from a N African ancestor, and N. African Sedum. Berger grouped the genera of that subfamily on the basis of polymerous flowers, but this is not restricted to this clade.[9][10]
Acre, with about 7 genera and 500 species is the most taxon rich clade in the Crasulaceae. It includes the American subfamily Echeveroideae and Sedum from Asia, Europe and Macaronesia, Mexico and Africa, including Sedum acre and Sedum subgenus Sedum.[36] The strong representation of Sedum in this large clade accounts for it comprising a third of the diversity of the family. Two subclades consist of the N American and Macaronesian taxa, the other Eurasian.[9][10]
The last subtribe, the Sedinae, represents the last four clades (4–7) and contained half of the genera and species of Crassulaceae, including Sedum, which is represented in all four clades, and the bulk of clades 5 and 7. In addition to Sedum, 16 other genera are recognised. Aeonium is basal divergence, followed by Sempervivum, with Leucosedum and Acre as sister groups. The Sedinae were very diverse, making phenotypic circumscription impossible. A similar problem exists for each of its subclades.[10][36] Given the realisation that Sedum s.l. was a highly artificial construction, there was support for reducing it by describing a number of segregate genera. Ohba (1995) proposed that Sedum s.s. should be restricted to clade 7, or at most clades 5–7, continuing some of the premolecular work in this direction, newly describing a number of Asian genera in addition to this reduced Sedum.:[31]
Hylotelephium
Orostachys
Aizopsis
Phedimus
Rhodiola
Prometheum
Rosularia
Balfouria
Sinocrassula
Meterostachys
Pseudosedum
The general phylogenetic topology described by 't Hart et al. (1995) was confirmed in a larger study of 112 species of Crassulaceae sampled from 33 genera, and all six recognized subfamilies, using the chloroplast gene matK. The Telephium clade, which had only been weakly supported, was seen as probably containing several subclades.[9] A similar conclusion was seen in a further but more focussed study of East Asian Sedoideae that examined the internal transcribed spacer (ITS) region of nuclear ribosomes of 74 taxa. This region includes about 300 species of Sedoideae, and most genera segregated from Sedum. However the Telephium clade of Ham was recognised as actually consisting of four separate clades, of which the two largest were named Hylotelephium and Rhodiola. The former are distinguished by being autumn flowering, while the remaining Sedeae bloom in spring and early summer. This analysis also confirmed the separate identity of most of the genera previously segregated from Sedum.[4] A second ITS study of 69 taxa in ten Asian genera resolved Telephium into just these two larger clades.[17]
Comparison of Infrafamilial Classifications of Crassulaceae
| Clade1[3] | Hart 1995[2] | Thiede & Eggli 2007[3] | ||||
|---|---|---|---|---|---|---|
| Subfamily | Tribe | Subtribe | Subfamily | Tribe | ||
| 1. Crassula | Crassuloideae | Crassuloideae | ||||
| 2. Kalanchoe | Sedoideae | Kalanchoeae | Kalanchoideae | |||
| 3. Telephium Hylotelephium2 |
Sedeae | Telephiinae | Sempervivoideae | Telephieae | ||
| Rhodiola3 | Umbiliceae | |||||
| 4. Sempervivum | Sedinae | Semperviveae | ||||
| 6. Aeonium | Aeonieae | |||||
| 5. Leucosedum | Sedeae | |||||
| 7. Acre | ||||||
| Notes:
1. Clade numbers following van Ham,[5] order following phylogeny of Thiede & Eggli |
||||||
Hart's taxonomic classification was revised by Thiede and Eggli (2007) to define three molecularly defined subfamilies, corresponding to the major clades, Crassuloideae, Kalanchoöideae and Sempervivoideae, and 34 genera.[24] Although some authors prefer the older term Sedoideae for Sempervivoideae,[11] Sempervivoideae has taxonomic priority.[18] The earliest branching subfamily is the Crassuloideae (2 genera), followed by the Kalanchoöideae (4 genera). Both of these represent the genera of southern Africa. The remaining six clades are segregated into the five tribes of the large temperate climate subfamily Sempervivoideae, with about thirty genera. These are Telephiae, Umbilicicae, Semperviveae, Aeonieae and Sedeae. Sedeae is the largest of these and contains two sister clades, Leucosedum and Acre[3] The Sempervivoideae contain many familiar horticultural plants, such as Sedum.[11] The phylogenetic relationships between the subfamilies are shown in the cladogram.
| Cladogram of Crassulaceae subfamilies[3] | |||||||||||||||
|
Subfamilies
Crassula capitella, the campfire plant
Crassula capitella
Crassuloideae Burnett
Crassuloideae is the smallest subfamily, representing a single monophyletic clade (Crassula), defined by haplostemonous androecia (characterized by a single whorl of stamens, the number of which equals the number of sepals, petals and carpels, and alternating with the petals). Although cosmopolitan in distribution, the center of diversity is southern Africa, with only the aquatic species being found more widely. It consists of two genera and about 250–300 species (Berger's other four genera (Dinacria, Pagella, Rochea, Vauanthes) having been subsumed into a larger Crassula s.l.). Crassula is morphologically diverse and up to 20 sections based on phenotypic features have been described. One of these, Tillaea, has at times been considered a separate genus. Hypagophytum is a monotypic genus,[3][10][37] alternatively considered under Sempervivoideae.[38]
Crassula L. (including Tillaea L.) c. 200 spp.
Hypagophytum A.Berger 1 sp.
Kalanchoe tomentosa, the panda plant
Kalanchoe tomentosa
Kalanchoöideae A.Berger
Kalanchoöideae is the next smallest subfamily, characterised by flower parts in fours. It represents Berger's Kalanchiodeae and Cotyledonoideae, in part. It is distributed in Madagascar and tropical Africa, with four genera and about between 130–240 species.[38] It is characterised by fused corollas, chromosome number x=9 and mostly southern African distribution. The boundaries between Kalanchoe, Bryophyllum and Kitchingia have remained unclear, and the latter two genera are more commonly treated as sections of Kalanchoe:[3][9][10][37]
Adromischus Lem.
Cotyledon L.
Kalanchoe Adans. (including Bryophyllum Adans., Kitchingia Adans.)
Tylecodon Toelken
Sempervivum tectorum, the common houseleek
Sempervivum tectorum
Sempervivoideae Arn.
Main article: Sempervivoideae
Sempervivoideae is the largest and taxonomically most complex subfamily, distributed in temperate climates, with about 20–30 genera, and divided into five tribes, of which Sedeae contains two distinct clades, Leucosedum and Acre:[3]
Telephieae
Umbiliceae
Semperviveae
Aeonieae
Sedeae
Distribution and habitat
The family Crassulaceae has a cosmopolitan distribution, particularly Crassula, though rare in South America and Australia,[5] predominantly in the temperate and subtropical regions of the Northern hemisphere and Africa. The main centers of diversity being Mexico and south-western USA (about 300 species), Southern Africa (about 250 species), the Mediterranean region (about 177 species) and adjacent Macaronesia archipelago (200 species), and south-eastern Asia (about 200 species), especially the Himalayas. The Mediterranean region includes 12 genera.[19] The greatest diversity is in southern Africa and Madagascar where the Crassula and Kalanchoe clades are confined.[9][10]
Habitat
Crassulaceae are found predominantly in semi-arid rocky habitats with monsoonal patterns of precipitation and high humidity, while some genera (e.g. Sempervivum) occur primarily in arid mountainous habitats and higher altitudes. Although their succulent leaves and Crassulacean acid metabolism allow them to adapt to a variable water supply, they are not found in true desert areas.[19][4] Some lineages have adapted to semi-aquatic and seasonally aquatic areas (Crassula (Tillaea), Sedella) while Echeveria and Aichryson are found in moist, cool forest areas.[10][11]
Ecology
While most Crassulaceae are perennial, Tillaea are annuals, and annual species are also found among Aichryson, Crassula, Sedum and Monanthes.[11]
Cultivation
Many Crassulaceae species are cultivated as pot plants or in rock gardens and borders.[8]
Toxicity
Toxic plants
Tylecodon wallichii plant
Tylecodon wallichii
Kalanchoe blossfeldiana
Some species are toxic to animals, such as those of Cotyledon and Tylecodon, e.g. Tylecodon wallichii.[39] All species of Kalanchoe are toxic, particularly to livestock in Australia and South Africa, where alternative forage is scarce, with the flowers containing the highest concentration of cardiotoxins, the active ingredient being bufadienolides (named for their digoxin-like effect on Bufo toads). Illness in domestic pets has also been reported, Kalanchoe blossfeldiana being a popular Christmastime decorative household plant.[40]
Uses
Crassula helmsii spreading in waterway
Crassula helmsii growing in wetland
Although no species have a role as crops, they are popular horticultural commodities as ornamental plants e.g. Kalanchoe,[10] while others (e.g. Crassula helmsii) may also have a nuisance role as weeds.[39]
Notes
Hendrik (Henk) t' Hart 1944–July 2000. Division of Plant Ecophysiology, Utrecht University[6]
References
APG IV 2016.
Hart 1995.
Thiede & Eggli 2007.
Mayuzumi & Ohba 2004.
van Ham & Hart 1998.
Eggli 2003.
Christenhusz et al 2017.
Hosch 2008.
Mort et al 2001.
Gontcharova & Gontcharov 2007.
Mort et al 2010.
Saint-Hilaire 1805.
de Lamarck & de Candolle 1815.
de Candolle 1828.
Berger 1930.
Anonymous 1937.
Gontcharova et al 2006.
Gontcharova & Gontcharov 2009.
Hart 1997.
Cronquist 1981.
Christenhusz & Byng 2016.
Takhtajan 1987.
Thorne 1992.
Stevens 2019.
Jian et al 2008.
Linnaeus 1753.
Ohba 1978.
Borisova 1939.
Borisova 1969.
Grulich 1984.
Ohba 1995.
Fröderströmm 1935.
Carillo-Reyes et al 2009.
Nikulin, Nikulin & Gontcharov 2015.
Tölken 1978.
Hart 1995a.
Rosen 2018.
Messerschmid et al 2020.
Wiersema & León 2016.
Gwaltney-Brant 2012.
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Christenhusz, Maarten J. M.; Fay, Michael F.; Chase, Mark W. (2017). "Saxifragales". Plants of the World: An Illustrated Encyclopedia of Vascular Plants. University of Chicago Press. pp. 231–244. ISBN 978-0-226-52292-0.
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Mitchell, John; Rook, Arthur James (1979). "Crassulaceae". Botanical Dermatology: Plants and Plant Products Injurious to the Skin. Greengrass. p. 226. ISBN 978-0-88978-047-7.
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Gwaltney-Brant, Sharon M. (2012). Christmastime Plants. pp. 419–512., in Peterson & Talcott (2012)
Hart, H. 't; Eggli, U. (1995). Introduction. pp. 7–15., in Hart & Eggli (1995)
Hart, H. 't (1995). Infrafamilial and generic classification of the Crassulaceae. pp. 159–172., in Hart & Eggli (1995)
Ohba, Hideaki (1995). Systematic problems of Asian Sedoideae. pp. 151–158., in Hart & Eggli (1995)
van Ham, R.C.H.J. (1995). Phylogenetic relationships in the Crassulaceae inferred from chloroplast DNA variation. pp. 16–29., in Hart & Eggli (1995)
Historical
Berger, A. (1930). "Crassulacaeae". In Engler, Adolf; Prantl, Karl Anton (eds.). Die Natürlichen Pflanzenfamilien. Vol. 18A. Leipzig: Verlag von Wilhelm Engelmann. pp. 352–483.
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de Lamarck; de Candolle (1815) [1805]. "Crassulaceae". Flore française ou descriptions succinctes de toutes les plantes qui croissent naturellement en France disposées selon une nouvelle méthode d'analyse; et précédées par un exposé des principes élémentaires de la botanique. Vol. 4 (3 ed.). Paris: Desray. pp. 382–398.
Gray, Samuel Frederick (1821). "Crassulaceae". A natural arrangement of British plants: according to their relations to each other as pointed out by Jussieu, De Candolle, Brown, &c. 2 vols. London: Baldwin, Cradock, and Joy. pp. ii: 538–543.
Linnaeus, Carl (1753). Species Plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Stockholm: Impensis Laurentii Salvii. pp. 282–283, 128–129, 429–30, 464–465, 1035, 430–432., see also Species Plantarum
Saint-Hilaire, Jean Henri Jaume (1805). "Crassuleae". Exposition des familles naturelles et de la germination des plantes, contentant la description de 2,337 genres et d'environ 4,000 espèces, 112 planches dont les figures ont été dessinées par l'auteur. vol II. Paris: Treuttel et Würtz. pp. 123–128.
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Anonymous (1937). "The Crassulaceae". The Cactus Journal. 5 (3): 51–53. ISSN 0950-7949. JSTOR 42784672.
Christenhusz, Maarten J.M. & Byng, J.W. (2016). "The number of known plants species in the world and its annual increase". Phytotaxa. Magnolia Press. 261 (3): 201–217. doi:10.11646/phytotaxa.261.3.1.
Grulich, Vit (1984). "Generic division of Sedoideae in Europe and the adjacent regions" (PDF). Preslia. 56: 29–45.
Hart, H. 't; Koek-Noorman, J. (November 1989). "The origin of the woody Sedoideae (Crassulaceae)". Taxon. 38 (4): 535–544. doi:10.2307/1222628. JSTOR 1222628.
Ohba, Hideaki (March 1977). "The taxonomic status of Sedum telephium and its allied species (Crassulaceae)". The Botanical Magazine Tokyo. 90 (1): 41–56. doi:10.1007/BF02489468. S2CID 22239507.
Ohba, H (1978). "Generic and infrageneric classification of the old world sedoideae crassulaceae". Journal of the Faculty of Science University of Tokyo Section III Botany. 12 (4): 139–193.
Thorne, Robert F. (1992). "Classification and Geography of the Flowering Plants". Botanical Review. 58 (3): 225–348. doi:10.1007/BF02858611. ISSN 0006-8101. JSTOR 4354190. S2CID 40348158.
Phylogeny
Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV". Botanical Journal of the Linnean Society. 181 (1): 1–20. doi:10.1111/boj.12385.
Carrillo-Reyes, Pablo; Sosa, Victoria; Mort, Mark E. (October 2009). "Molecular phylogeny of the Acre clade (Crassulaceae): Dealing with the lack of definitions for Echeveria and Sedum" (PDF). Molecular Phylogenetics and Evolution. 53 (1): 267–276. doi:10.1016/j.ympev.2009.05.022. PMID 19482091. Archived from the original (PDF) on 2019-08-24. Retrieved 2019-08-24.
Gontcharova, S. B.; Artyukova, E. V.; Gontcharov, A. A. (June 2006). "Phylogenetic relationships among members of the subfamily Sedoideae (Crassulaceae) inferred from the ITS region sequences of nuclear rDNA" (PDF). Russian Journal of Genetics. 42 (6): 654–661. doi:10.1134/S102279540606010X. S2CID 33249840. Archived from the original (PDF) on 2017-08-09. Retrieved 2019-09-27.
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Gontcharova, S. B.; Gontcharov, A. A. (11 October 2009). "Molecular phylogeny and systematics of flowering plants of the family Crassulaceae DC". Molecular Biology. 43 (5): 794–803. doi:10.1134/S0026893309050112. S2CID 39602334.
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Jian, Shuguang; Soltis, Pamela S.; Gitzendanner, Matthew A.; Moore, Michael J.; Li, Ruiqi; Hendry, Tory A.; Qiu, Yin-Long; Dhingra, Amit; Bell, Charles D.; Soltis, Douglas E. (February 2008). "Resolving an ancient, rapid radiation in Saxifragales". Systematic Biology. 57 (1): 38–57. doi:10.1080/10635150801888871. PMID 18275001.
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Messerschmid, Thibaud F.E.; Klein, Johannes T.; Kadereit, Gudrun; Kadereit, Joachim W. (4 September 2020). "Linnaeus's folly – phylogeny, evolution and classification of Sedum (Crassulaceae) and Crassulaceae subfamily Sempervivoideae". Taxon. 69 (5): 892–926. doi:10.1002/tax.12316.
Mort, Mark E.; Soltis, Douglas E.; Soltis, Pamela S.; Francisco-Ortega, Javier; Santos-Guerra, Arnoldo (January 2001). "Phylogenetic relationships and evolution of Crassulaceae inferred from matK sequence data". American Journal of Botany. 88 (1): 76–91. doi:10.2307/2657129. JSTOR 2657129. PMID 11159129.
Mort, Mark E.; Levsen, Nicholas; Randle, Christopher P.; Van Jaarsveld, Ernst; Palmer, Annie (July 2005). "Phylogenetics and diversification of Cotyledon (Crassulaceae) inferred from nuclear and chloroplast DNA sequence data". American Journal of Botany. 92 (7): 1170–1176. doi:10.3732/ajb.92.7.1170. PMID 21646139.
Mort, Mark E.; O'Leary, T. Ryan; Carrillo-Reyes, Pablo; Nowell, Tracey; Archibald, Jenny K.; Randle, Christopher P. (December 2010). "Phylogeny and evolution of Crassulaceae: Past, present, and future". Biodiversity & Ecology. 3: 69–86.
Nikulin, Arthur; Nikulin, Vyacheslav; Gontcharov, Andrey (October 2015). "To the question of phylogenetic structure of the tribe Telephieae (Sempervivoideae, Crassulaceae) based on ITS rDNA sequence comparisons". Botanicheskii Zhurnal (in Russian). 100 (10): 1030–1040.
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van Ham, Roeland C. H. J.; Hart, Henk ’t (January 1998). "Phylogenetic relationships in the Crassulaceae inferred from chloroplast DNA restriction-site variation". American Journal of Botany. 85 (1): 123–134. doi:10.2307/2446561. JSTOR 2446561. PMID 21684886.
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Websites
Hosch, William L. (27 Jun 2008). Crassulaceae. Encyclopædia Britannica. Retrieved 18 August 2019.
Stevens, P.F. (2019) [2001]. "Crassulaceae". AP Web v. 14. Missouri Botanical Garden. Retrieved 31 July 2019. (see also Angiosperm Phylogeny Website)
Fu, Kunjun; Ohba, Hideaki; Gilbert, Michael G. (2004). "Crassulaceae Candolle". p. 202. Retrieved 24 August 2019., in Flora of China online vol. 8
Rosen, Ralph (5 April 2018). "Crassuloideae". The Cactus Expert: World of Succulents. Retrieved 18 August 2019.
"International Crassulaceae Network". Retrieved 5 September 2019.
Etter, Julia; Kristen, Martin (2019). "The Crassulaceae database". Retrieved 9 October 2019.
Databases
"The Plant List Version 1.1: Crassulaceae". The Plant List. Royal Botanic Gardens, Kew and Missouri Botanical Garden. 2013. Retrieved 1 September 2019.
"Crassulaceae J.St.-Hil". World Flora Online. 2019. Retrieved 1 September 2019.
"Crassulaceae J.St.-Hil". Plants of the World Online. Royal Botanic Gardens, Kew. 2019. Retrieved 1 September 2019.
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