Cucurbitales Temporal range: Cretaceous – Recent Early | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Clade: | Fabids |
Order: | Cucurbitales Juss. ex Bercht. & J.Presl [1] |
Families | |
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Synonyms | |
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The Cucurbitales are an order of flowering plants, included in the rosid group of dicotyledons. This order mostly belongs to tropical areas, with limited presence in subtropical and temperate regions. The order includes shrubs and trees, together with many herbs and climbers. One major characteristic of the Cucurbitales is the presence of unisexual flowers, mostly pentacyclic, with thick pointed petals (whenever present). [2] The pollination is usually performed by insects, but wind pollination is also present (in Coriariaceae and Datiscaceae).
The order consists of roughly 2600 species in eight families. The largest families are Begoniaceae (begonia family) with around 1500 species and Cucurbitaceae (gourd family) with around 900 species. These two families include the only economically important plants. Specifically, the Cucurbitaceae (gourd family) include some food species, such as squash, pumpkin (both from Cucurbita ), watermelon (Citrullus vulgaris), and cucumber and melons ( Cucumis ). The Begoniaceae are known for their horticultural species, of which there are over 130 with many more varieties.
The Cucurbitales are an order of plants with a cosmopolitan distribution, particularly diverse in the tropics. [3] Most are herbs, climber herbs, woody lianas or shrubs but some genera include canopy-forming evergreen lauroid trees. [3] [4] Members of the Cucurbitales form an important component of low to montane tropical forest with greater representation in terms of the number of species. Although not known with certainty the total number of species in the order, conservative estimates indicate about 2600 species worldwide, distributed in 109 genera. [3] Compared to other flowering plant orders, the taxonomy is poorly understood due to their great diversity, difficulty in identification, and limited study.
The order Cucurbitales in the eurosid I clade comprises almost 2600 species in 109 or 110 genera in eight families, tropical and temperate, of very different sizes, morphology, and ecology. [3] It is a case of divergent evolution. In contrast, there is convergent evolution with other groups not related due to ecological or physical drivers toward a similar solution, including analogous structures. Some species are trees that have similar foliage to the true laurels due to convergent evolution. [3]
The patterns of speciation in the Cucurbitales are diversified in a high number of species. They have a pantropical distribution with centers of diversity in Africa, South America, and Southeast Asia. They most likely originated in West Gondwana 67–107 million years ago, so the oldest split could relate to the break-up of Gondwana in the middle Eocene to late Oligocene, 45–24 million years ago. The group reached their current distribution by multiple intercontinental dispersal events. One factor was product of aridification, other groups responded to favorable climatic periods and expanded across the available habitat, occurring as opportunistic species across wide distribution; other groups diverged over long periods within isolated areas. [3]
The Cucurbitales comprise the families: Apodanthaceae, Anisophylleaceae, Begoniaceae, Coriariaceae, Corynocarpaceae, Cucurbitaceae, Tetramelaceae, and Datiscaceae. [5] Some of the synapomorphies of the order are: leaves in spiral with secondary veins palmated, calyx or perianth valvate, and the elevated stomatal calyx/perianth bearing separate styles. The two whorls are similar in texture. [6]
Tetrameles nudiflora is a tree of immense proportions of height and width; Tetramelaceae, Anisophylleaceae, and Corynocarpaceae [7] are tall canopy trees in temperate and tropical forests. The genus Dendrosicyos , with the only species being the cucumber tree, is adapted to the arid semidesert island of Socotra. Deciduous perennial Cucurbitales lose all of their leaves for part of the year depending on variations in rainfall. The leaf loss coincides with the dry season in tropical, subtropical and arid regions. In temperate or polar climates, the dry season is due to the inability of the plant to absorb water available in the form of ice. Apodanthaceae are obligatory endoparasites that only emerge once a year in the form of small flowers that develop into small berries, however taxonomists have not agreed on the exact placement of this family within the Cucurbitales. Over half of the known members of this order belong to the greatly diverse begonia family Begoniaceae, with around 1500 species in two genera. Before modern DNA-molecular classifications, some Cucurbitales species were assigned to orders as diverse as Ranunculales, Malpighiales, Violales, and Rafflesiales. Early molecular studies revealed several surprises, such as the nonmonophyly of the traditional Datiscaceae, including Tetrameles and Octomeles , but the exact relationships among the families remain unclear. [3] The lack of knowledge about the order in general is due to many species being found in countries with limited economic means or unstable political environments, factors unsuitable for plant collection and detailed study. Thus the vast majority of species remain poorly determined, and a future increase in the number of species is expected.
Under the Cronquist system, the families Begoniaceae, Cucurbitaceae, and Datiscaceae were placed in the order Violales, within the subclass Dilleniidae, with the Tetramelaceae subsumed into the Datiscaceae. Corynocarpaceae was placed in order Celastrales, and Anisophylleaceae in order Rosales, both under subclass Rosidae. Coriariaceae was placed in Ranunculaceae, subclass Magnoliidae. Apodanthaceae was not recognised as a family, its genera being assigned to another parasitic plant family, the Rafflesiaceae. The present classification is due to APG III (2009).
Modern molecular phylogenetics suggest the following relationships: [2] [3] [8] [9] [10] [11] [12] [13]
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The Cucurbitaceae, also called cucurbits or the gourd family, are a plant family consisting of about 965 species in around 95 genera. Those most important to humans are the following:
The Laurales are an order of flowering plants. They are magnoliids, related to the Magnoliales.
The Magnoliales are an order of flowering plants.
Rosales is an order of flowering plants. It is sister to a clade consisting of Fagales and Cucurbitales. It contains about 7,700 species, distributed into about 260 genera. Rosales comprise nine families, the type family being the rose family, Rosaceae. The largest of these families are Rosaceae (90/2500) and Urticaceae (54/2600). The order Rosales is divided into three clades that have never been assigned a taxonomic rank. The basal clade consists of the family Rosaceae; another clade consists of four families, including Rhamnaceae; and the third clade consists of the four urticalean families.
The Nymphaeales are an order of flowering plants, consisting of three families of aquatic plants, the Hydatellaceae, the Cabombaceae, and the Nymphaeaceae. It is one of the three orders of basal angiosperms, an early-diverging grade of flowering plants. At least 10 morphological characters unite the Nymphaeales. One of the traits is the absence of a vascular cambium, which is required to produce both xylem (wood) and phloem, which therefore are missing. Molecular synapomorphies are also known.
The Araliaceae are a family of flowering plants composed of about 43 genera and around 1500 species consisting of primarily woody plants and some herbaceous plants commonly called the ginseng family. The morphology of Araliaceae varies widely, but it is predominantly distinguishable based on its woody habit, tropical distribution, and the presence of simple umbels.
Violales is a botanical name of an order of flowering plants and takes its name from the included family Violaceae; it was proposed by Lindley (1853). The name has been used in several systems, although some systems used the name Parietales for similar groupings. In the 1981 version of the influential Cronquist system, order Violales was placed in subclass Dilleniidae with a circumscription consisting of the families listed below. Some classifications such as that of Dahlgren placed the Violales in the superorder Violiflorae.
Saxifragaceae is a family of herbaceous perennial flowering plants, within the core eudicot order Saxifragales. The taxonomy of the family has been greatly revised and the scope much reduced in the era of molecular phylogenetic analysis. The family is divided into ten clades, with about 640 known species in about 35 accepted genera. About half of these consist of a single species, but about 400 of the species are in the type genus Saxifraga. The family is predominantly distributed in the northern hemisphere, but also in the Andes in South America.
Coriaria is the sole genus in the family Coriariaceae, which was described by Linnaeus in 1753. It includes 14 species of small trees, shrubs and subshrubs, with a widespread but disjunct distribution across warm temperate regions of the world, occurring as far apart as the Mediterranean region, southern and eastern Asia, New Zealand, the Pacific Ocean islands, and Central and South America.
The Kubitzki system is a system of plant taxonomy devised by Klaus Kubitzki, and is the product of an ongoing survey of vascular plants, entitled The Families and Genera of Vascular Plants, and extending to 15 volumes in 2018. The survey, in the form of an encyclopedia, is important as a comprehensive, multivolume treatment of the vascular plants, with keys to and descriptions of all families and genera, mostly by specialists in those groups. The Kubitzki system served as the basis for classification in Mabberley's Plant-Book, a dictionary of the vascular plants. Mabberley states, in his Introduction on page xi of the 2008 edition, that the Kubitzki system "has remained the standard to which other literature is compared".
The Rafflesiaceae are a family of rare parasitic plants comprising 36 species in 3 genera found in the tropical forests of east and southeast Asia, including Rafflesia arnoldii, which has the largest flowers of all plants. The plants are endoparasites of vines in the genus Tetrastigma (Vitaceae) and lack stems, leaves, roots, and any photosynthetic tissue. They rely entirely on their host plants for both water and nutrients, and only then emerge as flowers from the roots or lower stems of the host plants.
The Anisophylleaceae are a small family with four genera and about 70 species, in the order Cucurbitales, according to the APG II. However, it is more isolated from the other suprafamilial clades in this order, while it shows some similarities in flower morphology with the genus Ceratopetalum. Several wood features of this family are more primitive than those of the other families in the order Cucurbitales.
Octomeles is a monotypic genus of plant in family Tetramelaceae. The sole species is Octomeles sumatrana, sometimes written O. sumatranum.
Tetrameles is a genus of flowering plants in the family Tetramelaceae with one species, Tetrameles nudiflora. It grows as a large deciduous tree and is found across southern Asia from India through southeast Asia, Malesia, and into northern Australia.
When the APG II system of plant classification was published in April 2003, fifteen genera and three families were placed incertae sedis in the angiosperms, and were listed in a section of the appendix entitled "Taxa of uncertain position".
The family Apodanthaceae comprises about 10 species of endoparasitic herbs. They live in the branches or stems of their hosts, emerging only to flower and fruit. The plants produce no green parts and do not carry out any photosynthesis. There are two genera: Pilostyles and Apodanthes. A third genus, Berlinianche, was never validly published. Mitochondrial and nuclear DNA sequences confidently place the Apodanthaceae in the Cucurbitales, where they also fit well in terms of their flower morphology.
The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a further revision, the APG IV system.
The Cucurbiteae are a tribe of the subfamily Cucurbitoideae, which is part of the flowering plant family Cucurbitaceae (gourds). Species are usually monoecious herbaceous annuals or woody lianas.