Hamamelidaceae | |
---|---|
| |
Fothergilla major (Witch alder) | |
Scientific classification ![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Saxifragales |
Family: | Hamamelidaceae R.Br. [1] [2] |
Type genus | |
Hamamelis L. | |
Subfamilies | |
See text | |
![]() | |
The range of Hamamelidaceae. |
Hamamelidaceae, commonly referred to as the witch-hazel family, is a family of flowering plants in the order Saxifragales. The clade consists of shrubs and small trees positioned within the woody clade of the core Saxifragales. An earlier system, the Cronquist system, recognized Hamamelidaceae in the Hamamelidales order.
The Hamamelidaceae are distinguishable from other families in the Saxifragales due to the range of floral characteristics that are generally uniform though all genera. Uniform characteristics include stipules borne on stems with leaves often 2-ranked. [3] Genera usually have a two carpel gynoecium, although some species show variation. Other characteristics include a multicellular stigma, with shallow papillae or ridges. [4]
Anther structure and the modes of opening are considered to be one of the most important features in the systematics and evolution of hamamelids. The anthers in Hamamelids are on average shorter than in other families in the Saxifragales. [3] The anther valve openings are unique pleismorphic features that contrast with the simple longitudinal slits of the anthers in the upper Hamamelidae where the pollen is predominantly wind-driven. [5]
The three types of anthers found in the Hamamelidaceae are:
Plants of the Hamamelidaceae have sticky pollen, which may have influenced the type of pollination that is seen in this family. Pollination is predominantly via insects or wind. However, the insect-pollinated genus Disanthus has been known to wind-pollinate (although inefficiently) in the event pollinators do not visit its flowers. [6] The genus Rhodoleia is unique because it is bird-pollinated. [5] [3] [7]
The pollen structure in the lower Hamamelidae is relatively uniform. The pollen patterns are tricolpate [5] [3] with reticulate exines.
The petals of the Hamamelidaceae are generally narrow and ribbon-like. The exceptions are the genera Corylopsis and Rhodoleia, which have spathulate or circular-like petals. [5]
The flowers of Hamamelidaceae are mostly bisexual with perianth parts, which mature to fruits arranged in spikes, racemes or nonglobose heads. [5] [3]
The anemophilous groups within the Hamamelidaceae are often andromonoecious. Self-incompatibility is common, but self-compatibility occurs in some genera such as Hamamelis. [5]
The fossil record dates from the Eocene. [8] Hamamelidaceae was established by Brown in 1818 [1] as the Hamamelideae, including four genera. [9] The phylogenetic relationship of the Hamamelidaceae have been revisited several times since the first comprehensive classification of the family in 1930. [10] This was clarified in 1998 by the molecular phylogenetic work of the Angiosperm Phylogeny Group (APG) which placed the family within the eudicot order Saxifragales. In doing so, it separated one of the existing subfamilies, the Altingioideae, which formed the basal group, into its own family within the order, the Altingiaceae. [11]
Cladogram of Saxifragales families [12] [13] [2] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Cynomorium (Cynomoriaceae) remains unplaced within this tree |
The infrafamilial classification of the Hamamelidaceae has been controversial, and has undergone a number of revisions based on morphology, the best known of which are those of Harms (1930) [10] and Endress (1989). [5] [14] [15]
Morphological and DNA studies have supported monophyly of the Hamamelidoideae [16] [17] and have recognized the separation of the Rhodoleioideae and Disanthoideae subfamily and newly erected Mytilarioideae. [18] [14] [15] [19] [20] [21]
The relationships between Exbucklandioideae and the other subfamilies have proven controversial. The unresolved monophyly of Exbucklandioideae and the clades of Disanthoideae, Rhodoleioideae, Exbucklandioideae or even Mytilarioideae being a sister clade to Hamamelidoideae may have been a result of differing DNA methodologies researchers have used to produce phylogenetic trees and the inclusion or exclusion of certain genera used as outgroups in their analyses. However, the sister relationship of Disanthoideae and Hamamelidoideae has been well supported, [14] [17] [15] [22] although some researchers [16] do not support this. Strong support for making Altingioideae a family has been recognized by textbooks [3] and the Angiosperm Phylogeny Group. Research continues to resolve the deep relationships of the subfamilies within the Hamamelidaceae by incorporating whole or fragmentary fossil evidence. [18] [20]
Hamamelidaceae contains 27-30 genera and 80-140 species distributed among five to six subfamilies. The subfamilies are Exbucklandioideae, Rhodoleioideae, Mytilarioideae, Disanthoideae, Hamamelidoideae, and Altingioideae, which has been elevated to a family Altingiaceae in some recent treatments. [3] Many of the subfamilies are monotypic and the majority of the species lie within the Hamamelidoideae, which has 22 genera.
The long-standing question of whether Altingioideae should be a separate family has been assessed and supported by morphological and molecular phylogenetic studies. [2] [23] [3] [22] [24] The resulting subfamilial structure was eventually resolved in a series of molecular studies in the late 1990s, resulting in five distinct subfamilies, the majority of the genera residing in the nominative subfamily, Hamamelidoideae: [9]
The relatively large size of subfamily Hamamelidoideae and its further subdivision into tribes has also been a matter of study and controversy. Six tribes are now recognized. The revised structure has greatly reduced Hamamelideae to a monotypic taxon, which had previously been further divided into subtribes: [25]
The Hamamelidaceae were widely distributed in the Northern Hemisphere during the Upper Cretaceous and early Tertiary. [5] [18] Quaternary glaciation across the Northern Hemisphere caused the extinction of numerous species and the restricted distribution of others. Hamamelidaceae were obliterated from Europe along with numerous other genera of plants that were unable to escape the ice sheets due to geography (the Mediterranean Sea and Alps forming barriers that did not exist in North America and Asia) [26]
The largest subfamily, the Hamamelidoideae, is now distributed in North America and western and eastern Asia. The Hamamelidoideae subtribe Dicoryphinae is now restricted to the African (including Madagascar and Comores) and Australian continents. [26] [4] [14] Disanthoideae and Rhodoleioideae are now restricted to southern China and the Caucasus region. [26] Mytilarioideae is restricted to eastern Asia. Altingioideae is now restricted to eastern Asia and western Asia and North America between central Mexico and Belize. [26] [23]
The Malpighiales comprise one of the largest orders of flowering plants, containing about 36 families and more than 16,000 species, about 7.8% of the eudicots. The order is very diverse, containing plants as different as the willow, violet, poinsettia, manchineel, rafflesia and coca plant, and are hard to recognize except with molecular phylogenetic evidence. It is not part of any of the classification systems based only on plant morphology. Molecular clock calculations estimate the origin of stem group Malpighiales at around 100 million years ago (Mya) and the origin of crown group Malpighiales at about 90 Mya.
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 (91/4828) and Urticaceae (53/2625). 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.
Saxifragales is an order of angiosperms, or flowering plants, containing 15 botanical families and around 100 genera, with nearly 2,500 species. Of the 15 families, many are small, with eight of them being monotypic. The largest family is the Crassulaceae (stonecrops), a diverse group of mostly succulent plants, with about 35 genera. Saxifragales are found worldwide, primarily in temperate to subtropical zones, rarely being encountered growing wild in the tropics; however, many species are now cultivated throughout the world as knowledge of plant husbandry has improved. They can be found in a wide variety of environments, from deserts to fully aquatic habitats, with species adapted to alpine, forested or fully-aquatic habitats. Many are epiphytic or lithophytic, growing on exposed cliff faces, on trees or on rocks, and not requiring a highly organic or nutrient-dense substrate to thrive.
The Santalales are an order of flowering plants with a cosmopolitan distribution, but heavily concentrated in tropical and subtropical regions. It derives its name from its type genus Santalum (sandalwood). Mistletoe is the common name for a number of parasitic plants within the order.
The Cornales are an order of flowering plants, early diverging among the asterids, containing about 600 species. Plants within the Cornales usually have four-parted flowers, drupaceous fruits, and inferior to half-inferior gynoecia topped with disc-shaped nectaries.
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.
Amborella is a monotypic genus of understory shrubs or small trees endemic to the main island, Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family Amborellaceae and the order Amborellales and contains a single species, Amborella trichopoda. Amborella is of great interest to plant systematists because molecular phylogenetic analyses consistently place it as the sister group to all other flowering plants, meaning it was the earliest group to evolve separately from all other flowering plants.
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.
Commelinaceae is a family of flowering plants. In less formal contexts, the group is referred to as the dayflower family or spiderwort family. It is one of five families in the order Commelinales and by far the largest of these with about 731 known species in 41 genera. Well known genera include Commelina (dayflowers) and Tradescantia (spiderworts). The family is diverse in both the Old World tropics and the New World tropics, with some genera present in both. The variation in morphology, especially that of the flower and inflorescence, is considered to be exceptionally high amongst the angiosperms.
Dilleniaceae is a family of flowering plants with 11 genera and about 430 known species. Such a family has been universally recognized by taxonomists. It is known to gardeners for the genus Hibbertia, which contains many commercially valuable garden species.
Altingiaceae is a small family of flowering plants in the order Saxifragales, consisting of wind-pollinated trees that produce hard, woody fruits containing numerous seeds. The fruits have been studied in considerable detail. They naturally occur in Central America, Mexico, eastern North America, the eastern Mediterranean, China, and tropical Asia. They are often cultivated as ornamentals and many produce valuable wood.
The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants (angiosperms) which are mainly characterized by having two seed leaves (cotyledons) upon germination. The term derives from dicotyledon. Previously, they were called tricolpates or non-magnoliid dicots by past authors. The current botanical terms were introduced in 1991, by evolutionary botanist James A. Doyle and paleobotanist Carol L. Hotton, to emphasize the later evolutionary divergence of tricolpate dicots from earlier, less specialized, dicots.
The rosids are members of a large clade of flowering plants, containing about 70,000 species, more than a quarter of all angiosperms.
Chloranthaceae is a family of flowering plants (angiosperms), the only family in the order Chloranthales. It is not closely related to any other family of flowering plants, and is among the early-diverging lineages in the angiosperms. They are woody or weakly woody plants occurring in Southeast Asia, the Pacific, Madagascar, Central and South America, and the West Indies. The family consists of four extant genera, totalling about 77 known species according to Christenhusz and Byng in 2016. Some species are used in traditional medicine. The type genus is Chloranthus. The fossil record of the family, mostly represented by pollen such as Clavatipollenites, extends back to the dawn of the history of flowering plants in the Early Cretaceous, and has been found on all continents.
Peridiscaceae is a family of flowering plants in the order Saxifragales. Four genera comprise this family: Medusandra, Soyauxia, Peridiscus, and Whittonia., with a total of 12 known species. It has a disjunct distribution, with Peridiscus occurring in Venezuela and northern Brazil, Whittonia in Guyana, Medusandra in Cameroon, and Soyauxia in tropical West Africa. Whittonia is possibly extinct, being known from only one specimen collected below Kaieteur Falls in Guyana. In 2006, archeologists attempted to rediscover it, however, it proved unsuccessful.
Haloragaceae is a eudicot flowering plant family in the order Saxifragales, based on the phylogenetic APG system. In the Cronquist system, it was included in the order Haloragales.
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".
Tetracarpaea is the only genus in the flowering plant family Tetracarpaeaceae. Some taxonomists place it in the family Haloragaceae sensu lato, expanding that family from its traditional circumscription to include Penthorum and Tetracarpaea, and sometimes Aphanopetalum as well.
In phylogenetic nomenclature, the Pentapetalae are a large group of eudicots that were informally referred to as the "core eudicots" in some papers on angiosperm phylogenetics. They comprise an extremely large and diverse group accounting for about 65% of the species richness of the angiosperms, with wide variability in habit, morphology, chemistry, geographic distribution, and other attributes. Classical systematics, based solely on morphological information, was not able to recognize this group. In fact, the circumscription of the Pentapetalae as a clade is based on strong evidence obtained from DNA molecular analysis data.