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60-456: Petrosedum is a genus of the succulent family Crassulaceae (stonecrop family). Petrosedum is a genus in the family Crassulaceae , subfamily Sempervivoideae , tribe Semperviveae, together with two other genera. It was segregated from the very large cosmopolitan and polyphyletic genus, Sedum , where it was variously considered a series (Rupestria). It was originally described with eleven species. The following species are recognised in

120-496: A caudex , that is a swollen above-ground organ at soil level, formed from a stem, a root, or both. The storage of water often gives succulent plants a more swollen or fleshy appearance than other plants, a characteristic known as succulence. In addition to succulence, succulent plants variously have other water-saving features. These may include: Other than in Antarctica , succulents can be found within each continent. According to

180-462: A taxonomic category, since the term describes only the attributes of a particular species; some species in a genus such as Euphorbia , or family such as Asphodelaceae may be succulent, whereas others are less so or not at all. Many plant families have multiple succulent species found within them, more than 25 plant families. In some families, such as Aizoaceae , Cactaceae , and Crassulaceae , most species are succulents. In horticultural use,

240-1309: A broader construct of Sedum , recognising only Pseudosedum . In more recent times Ohba (1978) proposed the narrower view, segregating Rhodiola , Hylotelephium and Prometheum , among other genera. Ohba then subdivided the old world taxa of his now reduced Sedum into five subgenera: 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. As many as 32 segregate genera have been published, and most Eurasian crassulacean species were originally included in Sedum , but subsequently segregated ( see Sempervivoideae ). Subsequently, various revisions have proposed fewer subfamilies. Takhtajan (1987) initially submerged Sempervivoideae in Sedoideae and Cotyledonoideae in Kalanchiodeae to produce four, but later (1997) only three, Crassuloideae, Kalanchoideae and Sedoideae. Thorne (1992) also proposed three (Sedoidea, Cotyledonoidea, Crassuloidea), and then two (2000), Crassuloideae and Sempervivoideae. Prior to

300-614: 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. While the family can fairly easily be recognised, identifying its constituent genera has been far more problematic. For an extensive history of subfamily Sedoideae, see Ohba 1978 . Saint-Hilaire's original description in 1805 included seven genera, as did De Candolle (1815). In

360-419: A long ways without any or low water necessary. Some who grow succulents as a hobby may use the term in a different way from botanists. In horticultural use, the term succulent regularly excludes cacti. For example, Jacobsen's three volume Handbook of Succulent Plants does not include cacti. Many books covering the cultivation of these plants include "cacti (cactus) and succulents" as the title or part of

420-404: A mapping of morphological features and biogeography on the phylogenetic tree, see Mort et al 2001 Fig. 3. 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. When Carl Linnaeus published his Species Plantarum in 1753 only

480-534: 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. Two lineages, six subfamilies, and 33 genera of Crassulaceae were described by Berger in 1930: Lineages, subfamilies, biogeography, No. genera , type genus (No. species in genus) Each of these contained one of

540-649: A result, generic boundaries have been considered unclear with frequent intergradation of characteristics between taxa , which may represent recurrent adaptation to xeric habitats. Crassulaceae has been considered a part of the order Saxifragales by most modern authors, including Cronquist (1981), Takhtajan (1987), and Thorne (1992), based on phenotypic features, but subsequently confirmed by molecular methods. The place of Crassulaceae within Saxifragales has varied over time, as molecular data accumulates. The number of families within Saxifragales varies depending on

600-499: A separate clade, Rhodiola, in Thiede & Eggli, making an eighth clade. 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. Although some authors prefer the older term Sedoideae for Sempervivoideae, Sempervivoideae has taxonomic priority. The earliest branching subfamily

660-425: 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. However, a number of genera (e.g. Sempervivum , Aeonium ) are polymerous (3-32), have basally fused or partially fused corolla segments, where

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720-497: 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-sized 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

780-707: 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 . Most species are herbaceous leaf succulents, with regular 5 part (penta merous or fivemerous) flowers , isomerous free carpels and one or two whorls of stamens . Vegetative: Stems are sometimes succulent, as may also be

840-457: Is a thriving illegal trade in cacti and succulents. In South Africa, several species of succulent have been threatened with extinction due to poaching from the wild for the black market and mining related activities. The plants are mainly sold to collectors in Asian countries, where there has been a high demand for them. Since 1974, it is illegal to be in possession of protected succulents such as

900-433: Is any desert plant that a succulent plant collector wishes to grow", without any consideration of scientific classifications. Commercial presentations of "succulent" plants will present those that customers commonly identify as such. Plants offered commercially then as "succulents", such as hen and chicks , will less often include geophytes, in which the swollen storage organ is wholly underground, but will include plants with

960-463: Is often many-branched and bracteate . The flower clusters are red, yellow, or white. 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

1020-436: 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. Given the realisation that Sedum s.l. was a highly artificial construction, there

1080-770: Is that plant families are neither succulent nor non-succulent and can contain both. In many genera and families, there is a continuous gradation from plants with thin leaves and normal stems to those with very clearly thickened and fleshy leaves or stems. The succulent characteristic becomes meaningless for dividing plants into genera and families. Different sources may classify the same species differently. Species with intermediate characteristics such as somewhat fleshy leaves or stems may be described as semi-succulent . Horticulturists often follow commercial conventions and may exclude other groups of plants such as bromeliads , that scientifically are considered succulents. A practical horticultural definition has become "a succulent plant

1140-666: 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 The Sempervivoideae contain many familiar horticultural plants, such as Sedum . The phylogenetic relationships between

1200-637: 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

1260-1321: The Conophytum without authorisation in the Western Cape and Northern Cape , the two South African provinces where they grow. There are approximately sixty different plant families that contain succulents. Plant orders, families, and genera in which succulent species occur are listed below. Order Alismatales Order Apiales Order Arecales (also called Principes) Order Asparagales Order Asterales Order Brassicales Order Caryophyllales Order Commelinales Order Cornales Order Cucurbitales Order Dioscoreales Order Ericales Order Fabales Order Filicales Order Gentianales Order Geraniales Order Lamiales Order Malpighiales Order Malvales Order Myrtales Order Oxalidales Order Piperales Order Poales Order Ranunculales Order Rosales Order Santalales Order Sapindales Order Saxifragales Order Solanales Order Vitales Order Zygophyllales (unplaced order)* Boraginaceae : Heliotropium (unplaced order)* Icacinaceae : Pyrenacantha (geophyte) There also were some succulent gymnosperms (but extinct since

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1320-573: The Rosidae , 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 . 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

1380-547: The World Wildlife Fund , South Africa is home to around a third of all succulent species, most residing in the succulent Karoo biome. While it is often thought that most succulents come from dry areas such as steppes , semi-desert , and desert , the world's driest areas do not make for proper succulent habitats, mainly due to the difficulty such low growing plants or seedlings would have to thrive in environments where they could easily be covered by sand. Australia,

1440-503: The botanical authority . Authority has also, at times, been given to De Candolle (DC), who first used the term "Crassulaceae" in 1815. He later placed the family among the Dicotyledons . One of the most complete treatments was Alwin Berger 's revision in 1930. At that time the family comprised about 1,500 species, distributed over six subfamilies and 33 genera. Circumscription of

1500-521: 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). These clades were (1–7): 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

1560-893: 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. 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

1620-746: The Northern hemisphere the Sempervivoideae reached its greatest diversity. Conversely, few representatives of the Crassulaceae occur in South America and Australia. 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. The Macaronesian archipelago appears to have been reached by Crassulaceae at least three times. Once by

1680-664: 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

1740-626: The Sedoideae were problematic, being an artificial construction containing all taxa which could not be fitted into the other subfamilies ( catch-all ). 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, and 400 in Eastern and central Asia. Within Sedoideae,

1800-489: The Sedoideae. 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 . In contrast, Fröderströmm favoured retaining

1860-716: 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 . A second ITS study of 69 taxa in ten Asian genera resolved Telephium into just these two larger clades. 1. Clade numbers following van Ham, order following phylogeny of Thiede & Eggli 2. Thiede & Eggli renamed clade Telephium to Hylotelephium 3. Rhodiola and Umbilicus were included in Telephium by Hart, but formed

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1920-559: 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

1980-404: The ancestor of a lineage within the genus Umbilicus (Rhodiola clade). The Macronesian flora include three genera from the Sempervivoideae, 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

2040-431: The chloroplast gene matK . The Telephium clade, which had only been weakly supported, was seen as probably containing several subclades. 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

2100-431: 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 huge economic importance, internationally, as collectible, indoor and garden plants . Many species in

2160-496: The definition, many geophytes would be classed as succulents. Plants adapted to living in dry environments such as succulents, are termed xerophytes . Not all xerophytes are succulents, since there are other ways of adapting to a shortage of water, e.g., by developing small leaves which may roll up or having leathery rather than succulent leaves. Nor are all succulents xerophytes, as plants such as Crassula helmsii are both succulent and aquatic. Succulents allow themselves to go

2220-657: The degree of sympetaly , and phyllotaxis ) 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 . 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. Although five of his six subfamilies appeared to be morphologically and geographically defined,

2280-885: 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. Peridiscaceae Paeonia (Paeoniaceae) Altingiaceae Hamamelidaceae Cercidiphyllum (Cercidiphyllaceae) Daphniphyllum (Daphniphyllaceae) Crassulaceae Aphanopetalum (Aphanopetalaceae) Tetracarpaea (Tetracarpaeaceae) Penthorum (Penthoraceae) Haloragaceae s.s. Iteaceae (including Pterostemonaceae ) Ribes (Grossulariaceae) Saxifragaceae Crassulaceae evolved approximately 100–60 million years ago in southern Africa with

2340-485: The development of water-storing tissue. Other sources exclude roots as in the definition "a plant with thick, fleshy and swollen stems and/or leaves, adapted to dry environments". The difference affects the relationship between succulents and " geophytes "–plants that survive unfavorable seasons as a resting bud on an underground organ. The underground organs, such as bulbs , corms , and tubers , are often fleshy with water-storing tissues. Thus, if roots are included in

2400-541: The family has remained relatively stable, with the exception of the placement of the genus Penthorum and Tetracarpaea , which has at times been placed either in their own monogeneric family, Penthoraceae and Tetracarpaeaceae, or in the Saxifragaceae . When Penthorum and Tetracarpaea were separated from Crassulaceae, they became a natural monophyletic group. Some later authors, such as Cronquist , included only 900 species. Thiede and Eggli (2007), in their treatment of

2460-426: The family have a bizarre, alien and intriguing appearance, with interesting textures, growths or even "furry" coverings, and are quite hardy, typically needing only minimal care. Still, many others have a more typical, "conventional" rosette form, something reflected in many common names, such as 'black rose' often referring to Aeonium arboreum var. 'Swartzkopf' or var. 'Merlot'. Well-known genera and species include

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2520-400: The family, describe 34 genera with about 1,410 species. The size of the genera varies considerably, from Sedum , the largest with 300–500 species, to the smallest, which are monotypic . Estimates of the number of species has varied between 1500 (Berger 1930) and 900 (Cronquist 1981). Molecular phylogenetics has shown that morphological characters and chromosome numbers are so labile in

2580-399: 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. Crassulaceae is a medium size monophyletic grouping within the core eudicots . Originally considered a primitive member of

2640-469: The genus Petrosedum : This Crassulaceae -related article is a stub . You can help Misplaced Pages by expanding it . Crassulaceae Sempervivae [Sempervivaceae] Jussieu The Crassulaceae ( / ˈ k r æ s j uː l eɪ s iː ˌ iː , - s i ˌ aɪ / , 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

2700-576: The ground, and being dependent on their ability to store water and gaining nutrients by other means; it is seen in Tillandsia . Succulents also occur as inhabitants of sea coasts and dry lakes , which are exposed to high levels of dissolved minerals that are deadly to many other plant species. California is home to close to hundred succulent species that are native to the state, many of them live in coastal environments. Potted succulents are able to grow in most indoor environments with minimal care. There

2760-442: 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

2820-439: The largest genera. Though various revisions since have proposed simpler schemes, such as Borisova (1939, revised 1969). Berger's classification has proven practical and been the most widely used, although some of the subfamilies are polyphyletic. Berger's classification depended on biogeography and a number of morphological characteristics (primarily the number and arrangement of floral parts (haplostemonous androecia, polymery),

2880-399: 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. 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

2940-543: The many forms of Crassula ovata ('jade plant', 'money plant' or 'friendship tree'), Kalanchoe blossfeldiana (florists' or supermarket-kalanchoe); Cotyledon , such as 'Chalk Fingers' and ' Pig's Ear ', Sempervivum such as cobweb houseleek (or hen-and-chicks ) and S. calcareum , and Aeonium such as A. haworthii (and its popular variegate 'Kiwi'), A. arboreum, canariense , urbicum ; Monanthes , Umbilicus (pennywort), Bryophyllum , Echeveria , Sedum and Dudleya . General: Crassulaceae

3000-459: 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 ). 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

3060-510: 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 ), while Sedum includes much of the morphological diversity within the family as a whole. Although the typical number of floral parts is four or five, a number of genera, such as Sempervivum and Jovibarba , demonstrate polymery (at least ten or greater parts). Chromosome numbers are highly variable. The original base chromosome number

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3120-493: The remaining taxa are x=18. The core of this clade is probably polyploid from an ancestor with x=8. 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. Originally described by Saint-Hilaire (1805) as Crassuleae, and therefore has his name as

3180-929: The subfamilies are shown in the cladogram. Crassuloideae Kalanchoöideae Sempervivoideae Succulent Succulents may store water in various structures, such as leaves and stems . The water content of some succulent organs can get up to 90–95%, such as Glottiphyllum semicyllindricum and Mesembryanthemum barkleyii . Some definitions also include roots , thus geophytes that survive unfavorable periods by dying back to underground storage organs may be regarded as succulents. The habitats of these water-preserving plants are often in areas with high temperatures and low rainfall, such as deserts , but succulents may be found even in alpine ecosystems growing in rocky soil. Succulents are characterized by their ability to thrive on limited water sources, such as mist and dew, which makes them equipped to survive in an ecosystem that contains scarce water sources. Succulents are not

3240-424: The term is sometimes used in a way that excludes plants that botanists would regard as succulents, such as cacti . Succulents are often grown as ornamental plants because of their striking and unusual appearance, as well as their ability to thrive with relatively minimal care. By definition, succulent plants are drought -resistant plants in which the leaves, stem, or roots have become more than usually fleshy by

3300-631: The title. In botanical terminology, cacti are succulents, but not the reverse, as many succulent plants are not cacti. Cacti form a monophyletic group and apart from one species are native only to the New World , the Americas , but through parallel evolution similar looking plants in completely different families like the Apocynaceae evolved in the Old World. A further difficulty for general identification

3360-493: The two most basal phylogenetic branches (Crassula, Kalanchoe) representing the predominantly southern African members. Other sources suggest that Crassulaceae evolved approximately 70 million years ago together with Haloragaceae sensu lato ( Penthoraceae , Haloragaceae ). 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

3420-438: 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

3480-600: The use of molecular methods of classification, attempts to replace Berger's system were largely unsuccessful. Subsequently, Hart and colleagues (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. Hart utilized a hierarchical system of subfamilies, tribes and subtribes, based on molecular, geographical and morphological criteria, including embryology , pollen morphology and phytochemistry . The basal split at subfamily level, separates

3540-660: The world's driest inhabited continent, hosts very few native succulents due to the frequent and prolonged droughts. Even Africa, the continent with the most native succulents, does not host many of the plants in its most dry regions. While succulents are unable to grow in these harshest of conditions, they are able to grow in conditions that are uninhabitable by other plants. In fact, many succulents are able to thrive in dry conditions, and some are able to last up to two years without water depending on their surroundings and adaptations. Occasionally, succulents may occur as epiphytes , growing on other plants with limited or no contact with

3600-509: 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 .: 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

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