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46-671: Sempervivum ( / s ɛ m p ə ˈ v aɪ v əm / ) is a genus of about 40 species of flowering plants in the family Crassulaceae , commonly known as houseleeks . Other common names include liveforever (the source of the taxonomical designation Sempervivum , literally "always/forever alive") and hen and chicks , a name shared with plants of other genera as well. They are succulent perennials forming mats composed of tufted leaves in rosettes. In favourable conditions they spread rapidly via offsets , and several species are valued in cultivation as groundcover for dry, sunny locations. Houseleeks exist from Morocco to Iran, through

92-503: A calque of Ancient Greek ἀείζωον ("houseleek", literally "(the) forever-living (one)"), because this perennial plant keeps its leaves in winter and is very resistant to difficult conditions of growth. The common name "houseleek" comes from the Anglo-Saxon word leac , meaning "plant", since these are literally plants that grow on houses. They were believed to ward off fire and lightning strikes. Some Welsh people still hold

138-557: A species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in the nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,

184-651: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as

230-628: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,

276-668: A lot of them are not much different from each other. The main interest of these cultivars is not their flowers, but form and color of the rosette-leaves. The following species and cultivars - some of mixed or uncertain parentage - have gained the Royal Horticultural Society 's Award of Garden Merit :- Genus The composition of a genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including

322-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for

368-411: A result, after a few years, the plants lose their compact appearance and need to be re-rooted or propagated. In addition, if not removed, the shed leaves may decay, harboring fungus that can then infect the plant. They can be propagated easily by separating offsets, but also by leaf cuttings , and by seed if they are not hybrids. Echeveria has been extensively bred and hybridized . The following

414-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;

460-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and

506-612: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms

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552-451: Is furthermore said to bring relief in cases of swellings and water retention. The famous English herbalist Culpepper says 'Our ordinary Houseleek is good for all inward heats, as well as outward, and in the eyes or other parts of the body: a posset made of the juice is singularly good in all hot agues, for it cooleth and tempereth the blood and spirits and quencheth the thirst; and is also good to stay all deflection or sharp and salt rheums in

598-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,

644-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with

690-400: Is used presently for purported health benefits. It has no known side effects (aside from being an emetic in large doses) or drug interactions. Common herbal uses are stopping bad cases of diarrhea by drinking the juice of the leaf or eating the leaves directly, and the juice is commonly applied directly to the skin for many of the same uses as aloe vera such as burns, warts and insect bites. It

736-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to

782-824: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;

828-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,

874-473: The French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or the scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of

920-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of

966-527: The course of their lifetimes. Often numerous offsets are produced, and are commonly known as " hen and chicks ", which can also refer to other genera, such as Sempervivum , that are significantly different from Echeveria . Many species of Echeveria serve important environmental roles, such as those of host plants for butterflies . For example, the butterfly Callophrys xami uses several species of Echeveria , such as Echevelia gibbiflora , for suitable host plants. Even more, these plants are integral to

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1012-1163: The eyes, the juice being dropped into them. If the juice be dropped into the ears, it easeth pain.... It cooleth and restraineth all hot inflammations St. Anthony's fire (Erysipelas), scaldings and burnings, the shingles, fretting ulcers, ringworms and the like; and much easeth the pain and the gout.' Although their subtropical cousins are very frost-sensitive, sempervivums are among the most frost-resistant succulents, making them popular garden plants. They tend to grow best in dry conditions with well-draining, sandy soil to prevent soggy roots. They require only moderate watering, especially during warmer months, with occasional protection from extreme sun exposure. Sempervivums also make suitable plants for containers, and do well in breathable terracotta, concrete, and cement pots. They have also been known to grow in rock crevices , metal containers, succulent wreaths, roof shingles, and anywhere else that allows adequate root drainage. Collectors are numerous and often have many different cultivars in their collections. Sempervivums are very variable plants and hence hundreds, maybe thousands of cultivars have been created, but

1058-632: The flowers are actinomorphic (like a star) and have more than six petals, while in Jovibarba , the flowers are campanulate (bell-shaped) and are pale green-yellow with six petals . After flowering, the plant dies, usually leaving many offsets it has produced during its life. The genus Sempervivum is usually easy to recognize, although it may sometimes be confused with the genus Echeveria . However, its species are often not easy to identify. Even one single clone can look very different under various growth conditions ( modifications ) or different times of

1104-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this

1150-511: The genera Jovibarba , Aeonium , Greenovia , Aichryson , and Monanthes , occurring mainly in Macaronesia (Azores, Canary Islands, Cape Verde, Madeira). Some botanists include some or all of these genera within a wider interpretation of Sempervivum , particularly Jovibarba . The name Sempervivum has its origin in the Latin semper ("always") and vivus ("living"),

1196-737: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,

1242-446: The genus not to be monophyletic : species of Echeveria cluster with species of Cremnophila , Graptopetalum , Pachyphytum , and Thompsonella as well as species of Sedum sect. Pachysedum . The former Urbinia species do appear to form a monophyletic group within this grouping. Although it is clear that Echeveria is not monophyletic, its limits are not clear, and further analyses are needed to determine whether and how

1288-460: The genus should be split, or if it should be included in an expanded concept of Sedum . The International Crassulaceae Network accepts the following species: Many Echeveria species are popular as ornamental garden plants . They are drought-resistant, although they do better with regular deep watering and fertilizing. Most will tolerate shade and some frost, although hybrids tend to be less tolerant. Most lose their lower leaves in winter; as

1334-432: The idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of the same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but

1380-633: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,

1426-420: The limestone houseleek ( S. calcareum ). More rare are S. dolomiticum and S. pittonii , the latter which is endemic to Eastern Austria. On roofs or old walls S. tectorum can be found, more or less wild, very far out of its natural area. It is a very old medicinal and witch-plant. Some superstitious people believe this plant is able to protect a house from lightning . It has been used historically and

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1472-639: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Echeveria See text Courantia Lem. Echeveria is a large genus of flowering plants in the family Crassulaceae , native to semi-desert areas of Central America, Mexico and northwestern South America. Echeveria plants are evergreen . Flowers on short stalks (cymes) arise from compact rosettes of succulent fleshy, often brightly coloured leaves. Species are polycarpic , meaning that they may flower and set seed many times over

1518-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus

1564-653: The mountains of Iberia, the Alps, Carpathians, Balkan mountains, Turkey, the Armenian mountains, in the northeastern part of the Sahara Desert, and the Caucasus. Their ability to store water in their thick leaves allows them to live on sunny rocks and stony places in the mountain, subalpine and alpine belts. Most are hardy to US zone 4, and will handle warm climates to about zone 9. Morphologically, they are similar to

1610-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this

1656-833: The old folk belief that having it grow on the roof of the house ensures the health and prosperity of those who live there. The plant is not closely related to the true leek , which belongs to the Allium genus. Other common names reflect the plant's ancient association with Thor , the Norse god of thunder, and the Roman Jupiter , hence names such as "Jupiter's beard" and the German Donnerbart ("thunder beard"). Houseleeks grow as tufts of perennial but monocarpic rosettes . Each rosette propagates asexually by lateral rosettes (offsets, " hen and chicks "), by splitting of

1702-576: The oviposition process of C. xami and some other butterfly species as well. Echeveria is named for Atanasio Echeverría y Godoy , a botanical illustrator who contributed to Flora Mexicana . The genus was erected by A. P. de Candolle in 1828, and is named after the 18th century Mexican botanical artist Atanasio Echeverría y Godoy . As of June 2018 , the genus consists of about 150 species, including genera such as Oliveranthus and Urbinia that have formerly been split off from Echeveria . Molecular phylogenetic studies have repeatedly shown

1748-541: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for

1794-428: The rosette (only Jovibarba heuffelii ) or sexually by tiny seeds. Typically, each plant grows for several years before flowering. Their hermaphrodite flowers have first a male stage. Then the stamens curve themselves and spread away from the carpels at the center of the flower, so self-pollination is rather difficult. The colour of the flowers is reddish, yellowish, pinkish, or—seldom—whitish. In Sempervivum ,

1840-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,

1886-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being

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1932-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for

1978-576: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up

2024-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in

2070-450: The whole area of the genus, but there are many more local populations , without nomenclatural valour but sometimes with their own characters. In the Alps, the most distributed species are S. tectorum (common houseleek, sometimes called S. alpinum ), S. montanum (mountain houseleek) and S. arachnoideum (cobwebbed houseleek), each one with several subspecies. More local are the yellow-flowered S. wulfenii and S. grandiflorum , and

2116-400: The year. The members of this genus are very similar and closely linked to each other. As a consequence, many subspecies , varieties , and forms were described, without well-defined limits between them. As a second consequence, there is a high frequency of natural hybrids in this genus and the possibility of back-crossings of these. However, more or less 40 species can be individualized in

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