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Betulaceae Temporal range: | |
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Black alder ( Alnus glutinosa ) | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Fagales |
Family: | Betulaceae Gray [1] |
Type genus | |
Betula | |
Subfamilies and genera | |
See text | |
The range of the Betulaceae |
Betulaceae, the birch family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams, hazel-hornbeam, and hop-hornbeams numbering a total of 167 species. [2] They are mostly natives of the temperate Northern Hemisphere, with a few species reaching the Southern Hemisphere in the Andes in South America. Their typical flowers are catkins and often appear before leaves.
In the past, the family was often divided into two families, Betulaceae (Alnus, Betula) and Corylaceae (the rest). Recent treatments, including the Angiosperm Phylogeny Group, have described these two groups as subfamilies within an expanded Betulaceae: Betuloideae and Coryloideae.
Betulaceae flowers are monoecious, meaning that they have both male and female flowers on the same tree. Their flowers present as catkins and are small and inconspicuous, often with reduced perianth parts. These flowers have large feathery stamen and produce a high volume of pollen, as they rely on wind pollination. Their leaves are simple, with alternate arrangement and doubly serrate margins.
The Betulaceae are believed to have originated at the end of the Cretaceous period (about 70 million years ago) in central China. This region at the time would have had a Mediterranean climate due to the proximity of the Tethys Sea, which covered parts of present-day Tibet and Xinjiang into the early Tertiary period. This point of origin is supported by the fact that all six genera and 52 species are native to this region, many of those being endemic. All six modern genera are believed to have diverged fully by the Oligocene, with all genera in the family (with the exception of Ostryopsis ) having a fossil record stretching back at least 20 million years from the present.
According to molecular phylogeny, the closest relatives of the Betulaceae are the Casuarinaceae, or the she-oaks. [3]
The common hazel ( Corylus avellana ) and the filbert ( Corylus maxima ) are important orchard plants, grown for their edible nuts.
The other genera include a number of popular ornamental trees, widely planted in parks and large gardens; several of the birches are particularly valued for their smooth, brightly coloured bark.
The wood is generally hard, tough and heavy, hornbeams particularly so; several species were of significant importance in the past where very hard wood capable of withstanding heavy wear was required, such as for cartwheels, water wheels, cog wheels, tool handles, chopping boards, and wooden pegs. In most of these uses, wood has now been replaced by metal or other man-made materials.
Modern molecular phylogenetics suggest the following relationships: [3] [4] [5]
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Alders are trees comprising the genus Alnus in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few species extending into Central America, as well as the northern and southern Andes.
The Fagales are an order of flowering plants, including some of the best-known trees. The order name is derived from genus Fagus, beeches. They belong among the rosid group of dicotyledons. The families and genera currently included are as follows:
A birch is a thin-leaved deciduous hardwood tree of the genus Betula, in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus Betula contains 30 to 60 known taxa of which 11 are on the IUCN 2011 Red List of Threatened Species. They are a typically rather short-lived pioneer species widespread in the Northern Hemisphere, particularly in northern areas of temperate climates and in boreal climates.
Hornbeams are hardwood trees in the plant genus Carpinus in the family Betulaceae. The 30–40 species occur across much of the temperate regions of the Northern Hemisphere.
The Juglandaceae are a plant family known as the walnut family. They are trees, or sometimes shrubs, in the order Fagales. Members of this family are native to the Americas, Eurasia, and Southeast Asia.
Hazels are plants of the genus Corylus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is usually placed in the birch family Betulaceae, though some botanists split the hazels into a separate family Corylaceae. The fruit of the hazel is the hazelnut.
Alnus glutinosa, the common alder, black alder, European alder, European black alder, or just alder, is a species of tree in the family Betulaceae, native to most of Europe, southwest Asia and northern Africa. It thrives in wet locations where its association with the bacterium Frankia alni enables it to grow in poor quality soils. It is a medium-sized, short-lived tree growing to a height of up to 30 metres (98 feet). It has short-stalked rounded leaves and separate male and female flowers in the form of catkins. The small, rounded fruits are cone-like and the seeds are dispersed by wind and water.
The Ulmaceae are a family of flowering plants that includes the elms, and the zelkovas. Members of the family are widely distributed throughout the north temperate zone, and have a scattered distribution elsewhere except for Australasia.
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.
Betula nigra, the black birch, river birch or water birch, is a species of birch native to the Eastern United States from New Hampshire west to southern Minnesota, and south to northern Florida and west to Texas. It is one of the few heat-tolerant birches in a family of mostly cold-weather trees which do not thrive in USDA Zone 6 and up. B. nigra commonly occurs in floodplains and swamps.
A catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated. They contain many, usually unisexual flowers, arranged closely along a central stem that is often drooping. They are found in many plant families, including Betulaceae, Fagaceae, Moraceae, and Salicaceae.
Ostryopsis is a small genus of deciduous shrubs belonging to the birch family Betulaceae. The species have no common English name, though hazel-hornbeam has been suggested, reflecting their similarities to the closely related hazels and hop-hornbeams.
Hydrostachys is a genus of about 22 species of flowering plants native to Madagascar and southern and central Africa. It is the only genus in the family Hydrostachyaceae. All species of Hydrostachys are aquatic, growing on rocks in fast-moving water. They have tuberous roots, usually pinnately compound leaves, and highly reduced flowers on dense spikes.
Coleophora anatipennella is a moth of the case-bearer family (Coleophoridae).
Coleophora fuscocuprella is a moth of the family Coleophoridae. It is found from Fennoscandia to the Pyrenees, Italy, Albania and Romania and from Ireland to Russia.
Alnus serrulata, the hazel alder or smooth alder, is a thicket-forming shrub in the family Betulaceae. It is native to eastern North America and can be found from western Nova Scotia and southern New Brunswick south to Florida and Texas.
Coryloideae is a subfamily in the woody angiosperm family Betulaceae, commonly known as the birch family, and consists of four extant genera - Corylus L., Ostryopsis Decne., Carpinus L., and Ostrya Scop. These deciduous trees and shrubs are primarily distributed in the boreal and cool temperate zones of the Northern Hemisphere, with the majority occurring in Asia, many occurring in North America and a few species occurring as far south as South America. Synapomorphies such reduced staminate flowers, advanced wood anatomy features, and the presence of spermidines in pollen define the Coryloideae.
Carpinus perryae is an extinct species of hornbeam known from fossil fruits found in the Klondike Mountain Formation deposits of northern Washington state, dated to the early Eocene Ypresian stage. Based on described features, C. perryae is the oldest definite species in the genus Carpinus.