In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more they represent problematic species concepts. For example, the boundaries between related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, in a ring species. Among organisms that reproduce only asexually, the concept of a reproductive species breaks down, each clone is a microspecies. All species are given a two-part name, a "binomial"; the first part of a binomial is the genus.
The second part is called the specific epithet. For example, Boa constrictor is one of four species of the genus Boa. None of these is satisfactory definitions, but scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties. If species were fixed and distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, to grade into one another. Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped. Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection; that understanding was extended in the 20th century through genetics and population ecology. Genetic variability arises from mutations and recombination, while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures.
Genes can sometimes be exchanged between species by horizontal gene transfer. Viruses are a special case, driven by a balance of mutation and selection, can be treated as quasispecies. Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics. Early taxonomists such as Linnaeus had no option but to describe what they saw: this was formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or impossible to test. Biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: agamospecies for asexual organisms biospecies for reproductively isolated sexual organisms ecospecies based on ecological niches evolutionary species based on lineage genetic species based on gene pool morphospecies based on form or phenotype and taxonomic species, a species as determined by a taxonomist.
A typological species is a group of organisms in which individuals conform to certain fixed properties, so that pre-literate people recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens would differentiate the species; this method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, different phenotypes are not different species. Species named in this manner are called morphospecies. In the 1970s, Robert R. Sokal, Theodore J. Crovello and Peter Sneath proposed a variation on this, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms, it differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species is a group of sexually reproducing organisms that recognize one another as potential mates.
Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms. A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology, genes can move even between distantly related bacteria extending to the whole bacterial domain; as a rule of thumb, microbiologists have assumed that kinds of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA-DNA hybridisation to decide if they belong to the same species or not. This concept was narrowed in 2006 to a similarity of 98.7%. DNA-DNA hybri
Laelia is a small genus of 25 species in the orchid family. Laelia species are found in areas of subtropical or temperate climate in Central and South America, but in Mexico. Laelia is abbreviated L. in the horticultural trade. Epiphyte herbs with laterally compressed pseudobulbs. One to four leathery or fleshy leaves are born near the top of each pseudobulb, can be broadly ovate to oblong; the inflorescence is a terminal raceme. The flowers have 8 pollinia. Species of Laelia can be found from western Mexico south to Bolivia, from sea level to mountain forests; the genus Laelia was described as part of subfamily Epidendroideae by John Lindley. Brazilian Laelias, after being classified for several years under Sophronitis, have now been placed in the genus Cattleya. Moreover, species placed in the genus Schomburgkia have been moved either to the genus Laelia or Myrmecophila. Laelia comprises the following species: Species in this genus are found in forests from sea level to mountain habitats above 2000 m.
Species from above 2000 m of elevation like L. albida, L. autumnalis are adapted to temperate climates and can be grown outdoors in places like the Mexican Plateau and other subtropical areas with cool summers. Laelia is one of the orchid genera known to use crassulacean acid metabolism photosynthesis, which reduces evapotranspiration during daylight because carbon dioxide is collected at night. Laelias can be grown fastened to tree trunks, as long; the growing medium must have good drainage drying after watering. If grown mounted they need 50-70% humidity, while cooler temperatures increase the blooming process. Watering can be with lower frequency in winter. Fertilization can be done with a dilute solution, twice a month during growing season. Media related to Laelia at Wikimedia Commons
Brassavola is a genus of 21 orchids. They were named in 1813 by the Scottish botanist Robert Brown; the name comes from physician Antonio Musa Brassavola. This genus is abbreviated B. in trade journals. These species are widespread across Central America, the West Indies and South America, they are epiphytes, a few are lithophytes. A single and succulent leaf grows on an elongated pseudobulb; the orchid yields a raceme of a few flowers. The three sepals and two lateral petals are greenish and long; the base of the broad, sometimes fringed lip enfolds the column. This column contains twelve pollinia. Most Brassavola orchids are fragrant, attracting pollinators with their citrusy smell, but they are only fragrant at night. Longevity of flowers is between five and thirty days. In 1698 Brassavola nodosa was the first tropical orchid to be brought from the Caribbean island Curaçao to Holland, thus began the propagation of this orchid and the fascination for orchids in general. The species of Brassavola have been divided into four sections: This monotypic section, erected by H. G. Jones in 1969, contains the type of the genus: B. cucullata - Hooded brassavola, daddy longlegs orchid This section, erected by Rolfe in 1902, is characterized by narrow labella with fimbriate margins to wider labella with entire margins.
B. fasciculata B. filifolia B. flagellaris B. gardneri B. martiana B. perrinii B. reginae B. retusa B. revoluta B. rhomboglossa B. tuberculata This section, erected by Rolfe in 1902, is characterized by narrowly constricted labellum bases. The sectional type is B. nodosa B. gillettei B. grandiflora B. harrisii B. nodosa - Lady-of-the-night orchid B. subulifolia B. venosa This section, erected by H. G. Jones in 1975, is characterized by laterally-borne inflorescences; the sectional type is B. acaulis B. acaulis Other species accepted as of May 2014 but of unknown section: B. angustata B. ceboletta Brassavola is in the same alliance as the genera Cattleya and Laelia. They have been used extensively in hybridization and represent the "B" at the beginning of the names of such crosses. For example, Blc. is Brassolaeliocattleya. B. Little Stars, a primary hybrid between B. nodosa and B. subulifolia Rhynchovola David Sanders, a primary intergeneric hybrid between B. cucullata and Rhyncholaelia digbyana.
Rhyncolaelia digbyana was classified as a Brassavola. Brassocattleya Yellow Bird = Brassocattleya Richard Mueller × B. nodosa Brassocattleya Richard Mueller is a primary intergeneric hybrid between B. nodosa and C. milleri. C. milleri was classified as a Laelia until it was transferred into Sophronitis, sunk into Cattleya to avoid confusion. Media related to Brassavola at Wikimedia Commons Data related to Brassavola at Wikispecies
Broughtonia is a genus of orchids native to the Bahamas and the Greater Antilles. The genus is abbreviated Bro in trade journals; as presently constituted, Broughtonia consists of 6 accepted natural species plus one recognized nothospecies. Broughtonia cubensis Cogn. in I. Urban - Cuba Broughtonia domingensis Rolfe - Hispaniola, Mona Island Broughtonia × jamaicensis Sauleda & R. M. Adams - Jamaica Broughtonia lindenii Dressler - Cuba, Bahamas Broughtonia negrilensis Fowlie - Jamaica Broughtonia ortgiesiana Dressler - Cuba Broughtonia sanguinea R. Br. in W. T. Aiton - JamaicaThe haploid chromosome number of one species, B. sanguinea, has been determined as n = 20. Nir, M. Orchidaceae Antillanae, 49-52, 2000
The Orchidaceae are a diverse and widespread family of flowering plants, with blooms that are colourful and fragrant known as the orchid family. Along with the Asteraceae, they are one of the two largest families of flowering plants; the Orchidaceae have about 28,000 accepted species, distributed in about 763 genera. The determination of which family is larger is still under debate, because verified data on the members of such enormous families are continually in flux. Regardless, the number of orchid species nearly equals the number of bony fishes and is more than twice the number of bird species, about four times the number of mammal species; the family encompasses about 6–11% of all seed plants. The largest genera are Bulbophyllum, Epidendrum and Pleurothallis, it includes Vanilla–the genus of the vanilla plant, the type genus Orchis, many cultivated plants such as Phalaenopsis and Cattleya. Moreover, since the introduction of tropical species into cultivation in the 19th century, horticulturists have produced more than 100,000 hybrids and cultivars.
Orchids are distinguished from other plants, as they share some evident, shared derived characteristics, or synapomorphies. Among these are: bilateral symmetry of the flower, many resupinate flowers, a nearly always modified petal, fused stamens and carpels, small seeds. All orchids are perennial herbs, they can grow according to two patterns: Monopodial: The stem grows from a single bud, leaves are added from the apex each year and the stem grows longer accordingly. The stem of orchids with a monopodial growth can reach several metres in length, as in Vanda and Vanilla. Sympodial: Sympodial orchids have a front and a back; the plant produces a series of adjacent shoots, which grow to a certain size and stop growing and are replaced. Sympodial orchids grow laterally following the surface of their support; the growth continues by development of new leads, with their own leaves and roots, sprouting from or next to those of the previous year, as in Cattleya. While a new lead is developing, the rhizome may start its growth again from a so-called'eye', an undeveloped bud, thereby branching.
Sympodial orchids may have visible pseudobulbs joined by a rhizome, which creeps along the top or just beneath the soil. Terrestrial orchids may form corms or tubers; the root caps of terrestrial orchids are white. Some sympodial terrestrial orchids, such as Orchis and Ophrys, have two subterranean tuberous roots. One is used as a food reserve for wintry periods, provides for the development of the other one, from which visible growth develops. In warm and humid climates, many terrestrial orchids do not need pseudobulbs. Epiphytic orchids, those that grow upon a support, have modified aerial roots that can sometimes be a few meters long. In the older parts of the roots, a modified spongy epidermis, called velamen, has the function of absorbing humidity, it can have a silvery-grey, white or brown appearance. In some orchids, the velamen includes spongy and fibrous bodies near the passage cells, called tilosomes; the cells of the root epidermis grow at a right angle to the axis of the root to allow them to get a firm grasp on their support.
Nutrients for epiphytic orchids come from mineral dust, organic detritus, animal droppings and other substances collecting among on their supporting surfaces. The base of the stem of sympodial epiphytes, or in some species the entire stem, may be thickened to form a pseudobulb that contains nutrients and water for drier periods; the pseudobulb has a smooth surface with lengthwise grooves, can have different shapes conical or oblong. Its size is variable; some Dendrobium species have long, canelike pseudobulbs with short, rounded leaves over the whole length. With ageing, the pseudobulb becomes dormant. At this stage, it is called a backbulb. Backbulbs still hold nutrition for the plant, but a pseudobulb takes over, exploiting the last reserves accumulated in the backbulb, which dies off, too. A pseudobulb lives for about five years. Orchids without noticeable pseudobulbs are said to have growths, an individual component of a sympodial plant. Like most monocots, orchids have simple leaves with parallel veins, although some Vanilloideae have reticulate venation.
Leaves may be ovate, lanceolate, or orbiculate, variable in size on the individual plant. Their characteristics are diagnostic, they are alternate on the stem folded lengthwise along the centre, have no stipules. Orchid leaves have siliceous bodies called stegmata in the vascular bundle sheaths and are fibrous; the structure of the leaves corresponds to the specific habitat of the plant. Species that bask in sunlight, or grow on sites which can be very dry, have thick, leathery leaves and the laminae are covered by a waxy cuticle to retain their necessary water supply. Shade-loving species, on the other hand, have thin leaves; the leaves of most orchids are perennial, that is, they live for several years, while others those with plicate leaves as in Catasetum, shed them annually and de
Cattleya is a genus of orchids from Costa Rica south to Argentina. The genus is abbreviated C in trade journals. Epiphytic or terrestrial orchids with cylindrical rhizome from which the fleshy noodle-like roots grow. Pseudobulbs can be spindle-shaped or cylindrical; the leaves can be lanceolate or elliptical, somewhat fleshy, with smooth margin. The inflorescence is a terminal raceme with several flowers. Flowers have petals free from each other. There are four polliniums; the fruit is a capsule with many small seeds. The genus was named in 1824 by John Lindley after horticulturalist William Cattley. Cattley obtained a specimen of unnamed Cattleya labiata from William Swainson who had discovered the new plant in Pernambuco, Brazil, in 1817; the plant bloomed under the care of Cattley and it became the type specimen from which Lindley described C. labiata. Accepted species and subgeneric division within genus Cattleya are: C. aurea C. dowiana. C. gaskelliana. C. iricolor. C. jenmanii. C. labiata C. luteola.
C. mendelii. C. mooreana. C. mossiae C. percivaliana. C. quadricolor C. rex. C. schroederae. C. trianae. C. warneri. C. warscewiczii. C. crispa C. grandis. C. lobata C. perrinii C. purpurata C. tenebrosa. C. virens C. xanthina. C. alaorii. C. bicalhoi. C. jongheana. C. praestans C. pumila C. sincorana. C. lundii. C. alvarenguensis C. alvaroana. C. angereri. C. blumenscheinii. C. bradei. C. briegeri. C. campacii. C. caulescens. C. cinnabarina. C. colnagoi. C. conceicionensis Brazil - Minas Gerais) C. crispata C. endsfeldzii. C. esalqueana. C. flavasulina C. fournieri C. ghillanyi. C. gloedeniana C. gracilis. C. hatae C. hegeriana C. hispidula. C. hoehnei C. itambana. C. kautskyana. C. kettieana C. kleberi C. liliputana. C. locatellii C. longipes. C. luetzelburgii. C. macrobulbosa C. marcaliana. C. milleri. C. mirandae. C. munchowiana. C. neokautskyi C. pabstii C. pendula C. pfisteri. C. presidentensis. C. reginae. C. rupestris. C. viridiflora C. acuensis. C. alagoensis C. brevipedunculata. C. cernua. C. coccinea. C. dichroma. C. mantiqueirae.
C. pygmaea. C. wittigiana. C. lawrenceana. C. lueddemanniana. C. wallisii C. araguaiensis C. aclandiae C. amethystoglossa C. bicolor C. dormaniana C. elongata C. forbesii C. granulosa C. guttata. C. harrisoniana. C. intermedia. C. kerrii. C. loddigesii. C. nobilior. C. porphyroglossa. C. schilleriana. C. schofieldiana C. tenuis. C. tigrina. C. velutina C. violacea. C. walkeriana. C. maxima. Accepted natural hybrids are: This section is incomplete. Hybrids of Cattleya and other genera are placed in the following nothogenera: Brassocattleya = Brassavola × Cattleya Brassolaeliocattleya = Brassavola × Cattleya × Laelia Cattleytonia = Cattleya × Broughtonia Rhyncholaeliocattleya = Rhyncholaelia × Cattleya LightCattleyas need light, but not direct sunlight. TemperatureDay temperatures must be between 25-30 °C and night temperatures not lower than 10-12 °C. HumidityMust be between 40-70% with good ventilation. WateringWater only if substrate is dry, it can be done once a week. FertilizingCattleyas can survive without fertilizing.
However, it is advisable to use nitrogen-base
Asparagales is an order of plants in modern classification systems such as the Angiosperm Phylogeny Group and the Angiosperm Phylogeny Web. The order takes its name from the type family Asparagaceae and is placed in the monocots amongst the lilioid monocots; the order has only been recognized in classification systems. It was first put forward by Huber in 1977 and taken up in the Dahlgren system of 1985 and the APG in 1998, 2003 and 2009. Before this, many of its families were assigned to the old order Liliales, a large order containing all monocots with colourful tepals and lacking starch in their endosperm. DNA sequence analysis indicated that many of the taxa included in Liliales should be redistributed over three orders, Liliales and Dioscoreales; the boundaries of the Asparagales and of its families have undergone a series of changes in recent years. In the APG circumscription, Asparagales is the largest order of monocots with 14 families, 1,122 genera, about 36,000 species; the order is circumscribed on the basis of molecular phylogenetics, but is difficult to define morphologically, since its members are structurally diverse.
Most species of Asparagales are herbaceous perennials, although some are climbers and some are tree-like. The order contains many geophytes. According to telomere sequence, at least two evolutionary switch-points happened within the order. Basal sequence is formed by TTTAGGG like in majority of higher plants. Basal motif was changed to vertebrate-like TTAGGG and the most divergent motif CTCGGTTATGGG appears in Allium. One of the defining characteristics of the order is the presence of phytomelanin, a black pigment present in the seed coat, creating a dark crust. Phytomelanin is found in most families of the Asparagales; the leaves of all species form a tight rosette, either at the base of the plant or at the end of the stem, but along the stem. The flowers are not distinctive, being'lily type', with six tepals and up to six stamina; the order is thought to have first diverged from other related monocots some 120–130 million years ago, although given the difficulty in classifying the families involved, estimates are to be uncertain.
From an economic point of view, the order Asparagales is second in importance within the monocots to the order Poales. Species are used as food and flavourings, as cut flowers, as garden ornamentals. Although most species in the order are herbaceous, some no more than 15 cm high, there are a number of climbers, as well as several genera forming trees, which can exceed 10 m in height. Succulent genera occur in several families. All species have a tight cluster of leaves, either at the base of the plant or at the end of a more-or-less woody stem as with Yucca. In some cases the leaves are produced along the stem; the flowers are in the main not distinctive, being of a general'lily type', with six tepals, either free or fused from the base and up to six stamina. They are clustered at the end of the plant stem; the Asparagales are distinguished from the Liliales by the lack of markings on the tepals, the presence of septal nectaries in the ovaries, rather than the bases of the tepals or stamen filaments, the presence of secondary growth.
They are geophytes, but with linear leaves, a lack of fine reticular venation. The seeds characteristically have the external epidermis either obliterated, or if present, have a layer of black carbonaceous phytomelanin in species with dry fruits; the inner part of the seed coat is collapsed, in contrast to Liliales whose seeds have a well developed outer epidermis, lack phytomelanin, display a cellular inner layer. The orders which have been separated from the old Liliales are difficult to characterize. No single morphological character appears to be diagnostic of the order Asparagales; the flowers of Asparagales are of a general type among the lilioid monocots. Compared to Liliales, they have plain tepals without markings in the form of dots. If nectaries are present, they are in the septa of the ovaries rather than at the base of the tepals or stamens; those species which have large dry seeds have a dark, crust-like outer layer containing the pigment phytomelan. However, some species with hairy seeds, berries, or reduced seeds lack this dark pigment in their seed coats.
Phytomelan is not unique to Asparagales but it is common within the order and rare outside it. The inner portion of the seed coat is completely collapsed. In contrast, the morphologically similar seeds of Liliales have no phytomelan, retain a cellular structure in the inner portion of the seed coat. Most monocots are unable to thicken their stems once they have formed, since they lack the cylindrical meristem present in other angiosperm groups. Asparagales have a method of secondary thickening, otherwise only found inDioscorea. In a process called'anomalous secondary growth', they are able to create new