Pyrus calleryana | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Rosales |
Family: | Rosaceae |
Genus: | Pyrus |
Species: | P. calleryana |
Binomial name | |
Pyrus calleryana | |
Synonyms [1] | |
List
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Pyrus calleryana, also known as the Callery pear or Bradford pear, is a species of pear tree native to China and Vietnam, [2] in the family Rosaceae. It is most commonly known for its cultivar 'Bradford' and its offensive odor, widely planted throughout the United States and increasingly regarded as an invasive species. [2]
Pyrus calleryana is deciduous, growing to 5 to 8 m (16 to 26 ft) tall, [3] often with a conical to rounded crown. The leaves are oval, 4 to 8 cm (1+1⁄2 to 3 in) long, glossy dark green above and pale beneath. They have long petioles alternately arranged on branches. [4] The white, five-petaled flowers are about 2 to 2.5 cm (3⁄4 to 1 in) in diameter. They are produced abundantly in early spring, before the leaves expand fully.
The fruits (which are often assumed to be inedible due to their abundant, cyanide laced seeds) of the Callery pear are small (less than 1 centimetre (3⁄8 in) in diameter), and hard, almost woody, until softened by frost, after which they are readily taken by birds, which disperse the seeds in their droppings. In summer, the shining foliage is dark green and very smooth, and in autumn the leaves commonly turn brilliant colors, ranging from yellow and orange to more commonly red, pink, purple, and bronze. However, since the color often develops very late in autumn, the leaves may be killed by a hard frost before full color can develop.
Callery pears are remarkably resistant to disease or fireblight. However, some cultivars, such as 'Bradford', are particularly susceptible to storm damage and are regularly disfigured or killed by strong winds, winter weather, or limb loss due to their naturally rapid growth rate.
The species is named after the Italian-French missionary Joseph-Marie Callery (1810–1862), a sinologue who sent specimens of the tree to Europe from China. [5] [6]
Numerous cultivars of Callery pear are offered commercially, including 'Aristocrat', 'Autumn Blaze', 'Bradford', 'Capital', 'Chanticleer' (also known as 'Cleveland Select'), 'New Bradford', 'Redspire', and 'Whitehouse'.[ citation needed ]
The trees were introduced to the U.S. by the United States Department of Agriculture facility at Glenn Dale, Maryland, as ornamental landscape trees in the mid-1960s. They became popular with landscapers because they were inexpensive, transported well and grew quickly. Lady Bird Johnson promoted the tree in 1966 by planting one in downtown Washington, D.C. [7] [8] The New York Times also promoted the tree saying, "Few trees possess every desired attribute, but the Bradford ornamental pear comes unusually close to the ideal." [9]
In much of North America these cultivars, particularly 'Bradford', are widely planted as ornamental trees. The trees are tolerant of a variety of soil types, drainage levels, and soil acidity. Their crown shape varies from ovate to elliptical, but may become asymmetric from limb loss due to excessive and unstable growth rate. The initial symmetry of several cultivars leads to their attempted use in settings such as industrial parks, streets, shopping centers, and office parks. Their dense clusters of white blossoms are conspicuous in early spring, with an odor often compared to rotting fish or semen. [10] [11] [12] [13] According to extension specialist Kelly Oten of North Carolina State University, the smell attracts flies which are the primary pollinators rather than bees. [14] At the latitude of Pittsburgh, Pennsylvania, the trees often remain green until mid-November,[ citation needed ] and in warm autumns, the colors are often bright, although in a cold year they may get frozen off before coloring. In the South, Callery pears tend to be among the more reliable coloring trees.[ citation needed ]
The following varieties are currently accepted: [1]
The Bradford pear and related cultivars of Pyrus calleryana are regarded as invasive species in many areas of the Eastern and Midwestern regions in North America, outcompeting many native plants and trees. [2] In the northeastern United States, wild Callery pears sometimes form extensive, nearly homogeneous stands in old fields, along roadsides, and in similar disturbed areas. The species was first noticed spreading outside of human cultivation in the 1990s, and by the latter half of the 2000s, Callery pear trees were widespread and could be found in habitats ranging from wetlands to forests. [15]
While various cultivars of the Callery pear are commonly planted for their ornamental value, their prolifically produced fruits are taken by birds, which disperse the seeds in their droppings. The various cultivars are generally themselves self-incompatible, unable to produce fertile seeds when self-pollinated, or cross-pollinated with another tree of the same cultivar. However, if different cultivars of Callery pears are grown in proximity (within insect-pollination distance, about 300 ft or 100 m), [2] they often produce fertile seeds that can sprout and establish wherever they are dispersed. The resulting wild individuals, of various genetic backgrounds, can in turn interbreed, producing more viable seed and furthering expansion and dispersal of the wild stand of the species. These plants often differ from the selected cultivars in their irregular crown shape and (sometimes) presence of thorns.[ citation needed ]
Callery pear is reported as established outside cultivation in 152 counties in 25 states in the United States. [16] While these wild plants are sometimes called "Bradford pear" (for the 'Bradford' cultivar), they are actually wild-growing descendants of multiple genotypes of Pyrus calleryana, and hence more correctly referred to by the common (or scientific) name of the species itself. [2] Currently, the spread of the invasive trees is limited by their intolerance to extreme cold, but they are creeping northward as climate change causes warming temperatures, and have been found as far north as Madison, Wisconsin. [17]
The Bradford pear in particular has become further regarded as a nuisance tree for its initially neat, dense upward growth, which made it desirable in cramped urban spaces. Without corrective selective pruning at an early stage, these weak crotches result in a multitude of narrow, weak forks that are very susceptible to storm damage. Because of this, and the resulting relatively short life span (typically less than 25 years), many groups have discouraged further planting of 'Bradford' and other similarly structurally deficient Callery pear cultivars (such as 'Cleveland Select') in favor of increasing use of locally native ornamental tree species. [18]
In 2023, the state of Ohio banned the sale and cultivation of Callery pear trees. [19]
Pear wood (of any species) is among the finest-textured of all fruitwoods. It is prized for making woodwind instruments, and pear veneer is used in fine furniture. [20] Pear wood is also among those preferred for preparing woodcuts for printing, either end-grained for small works or side-grained for larger. [21]
Callery pear has been used as rootstock for grafting such pear cultivars as Comice, Bosc, or Seckel, and especially for Nashi. Pyrus calleryana was first introduced into the United States in 1909 and 1916, largely influenced by the dedicated research of Frank N. Meyer, plant explorer for the US Department of Agriculture, commonly known for the discovery of the Meyer lemon, for agricultural experimentation, pre-dating recognition in the 1950s of the species' potential as an ornamental plant. [2]
Pears are fruits produced and consumed around the world, growing on a tree and harvested in late summer into mid-autumn. The pear tree and shrub are a species of genus Pyrus, in the family Rosaceae, bearing the pomaceous fruit of the same name. Several species of pears are valued for their edible fruit and juices, while others are cultivated as trees.
Malus is a genus of about 32–57 species of small deciduous trees or shrubs in the family Rosaceae, including the domesticated orchard apple, crab apples and wild apples.
Rosa multiflora is a species of rose known commonly as multiflora rose, baby rose, Japanese rose, many-flowered rose, seven-sisters rose, Eijitsu rose and rambler rose. It is native to eastern Asia, in China, Japan, and Korea. It should not be confused with Rosa rugosa, which is also known as "Japanese rose", or with polyantha roses which are garden cultivars derived from hybrids of R. multiflora. It was introduced to North America, where it is regarded as an invasive species.
Pyrus pyrifolia is a species of pear tree native to southern China and northern Indochina that has been introduced to Korea, Japan and other parts of the world. The tree's edible fruit is known by many names, including Asian pear, Persian pear, Japanese pear, Chinese pear, Korean pear, Taiwanese pear, apple pear, zodiac pear, three-halves pear, papple, naspati and sand pear. Along with cultivars of P. × bretschneideri and P. ussuriensis, the fruit is also called the nashi pear. Cultivars derived from Pyrus pyrifolia are grown throughout East Asia, and in other countries such as India, Pakistan, Nepal, Australia, New Zealand, and the United States. Traditionally in East Asia the tree's flowers are a popular symbol of early spring, and it is a common sight in gardens and the countryside.
Cercidiphyllum is a genus containing two species of plants, both commonly called katsura. They are the sole members of the monotypic family Cercidiphyllaceae. The genus is native to Japan and China and unrelated to Cercis (redbuds).
Magnolia tripetala, commonly called umbrella magnolia or simply umbrella-tree, is a deciduous tree native to the eastern United States in the Appalachian Mountains, the Ozarks, and the Ouachita Mountains. The name "umbrella tree" derives from the fact that the large leaves are clustered at the tips of the branches forming an umbrella-shaped structure.
Pyrus communis, the common pear, is a species of pear native to central and eastern Europe, and western Asia.
Juniperus squamata, the flaky juniper, or Himalayan juniper is a species of coniferous shrub in the cypress family Cupressaceae, native to the Himalayas and China.
Ulmus bergmannianaC.K.Schneid., commonly known as Bergmann's elm, is a deciduous tree found across much of China in forests at elevations of 1500–3000 m.
Euonymus fortunei, the spindle, Fortune's spindle, winter creeper or wintercreeper, is a species of flowering plant in the family Celastraceae, native to east Asia, including China, Korea, the Philippines and Japan. E. fortunei is highly invasive and damaging in the United States, causing the death of trees and forest in urban areas.
Rosa chinensis, known commonly as the China rose, Chinese rose, or Bengal rose, is a member of the genus Rosa native to Southwest China in Guizhou, Hubei, and Sichuan Provinces. The first publication of Rosa chinensis was in 1768 by Nikolaus Joseph von Jacquin in Observationum Botanicarum, 3, p. 7 & plate 55.
Fraxinus mandshurica, the Manchurian ash, is a species of Fraxinus native to northeastern Asia in northern China, Korea, Japan and southeastern Russia.
Ulmus laciniata var. nikkoensisRehder, the Nikko elm, was discovered as a seedling near Lake Chūzenji, near Nikkō, Japan, and obtained by the Arnold Arboretum in 1905. The taxonomy of the tree remains a matter of contention, and has been considered possibly a hybrid of U. laciniata and U. davidiana var. japonica. However, in crossability experiments at the Arnold Arboretum in the 1970s, U. laciniata, a protogynous species, was found to be incompatible with U. davidiana var. japonica, which is protandrous.
Gymnosporangium sabinae is a species of rust fungus in the subdivision Pucciniomycotina. Known as pear rust, European pear rust, or pear trellis rust, it is a heteroecious plant pathogen with Juniperus sabina as the main primary (telial) host and Pyrus communis as the main secondary (aecial) host.
Frank Nicholas Meyer was a United States Department of Agriculture explorer who travelled to Asia to collect new plant species. The Meyer lemon was named in his honor.
Acer palmatum, commonly known as Japanese maple, palmate maple, or smooth Japanese maple (Korean: danpungnamu, 단풍나무, Japanese: irohamomiji, イロハモミジ, or momiji,, is a species of woody plant native to Korea, Japan, China, eastern Mongolia, and southeast Russia. Many different cultivars of this maple have been selected and they are grown worldwide for their large variety of attractive forms, leaf shapes, and spectacular colors.
Pyrus bourgaeana, the Iberian pear, is a close relative of Pyrus communis L. The latter was domesticated about 2500 years ago. This small tree is widely distributed across the southern Iberian Peninsula and northern Morocco, where it coexists with four Pyrus species: P. communis L., P. cordata Dew., P. spinosa Forssk, and P. nivalis Jacq. Characteristics to discriminate these species are the width of fruit peduncle, petal size, leaf width and petiole length served to the taxa.
Pyrus cordata, the Heart-leaved pear or Plymouth pear, is a rare wild species of pear belonging to the family Rosaceae. It gets its name in Spanish, Portuguese and French from the shape of its leaves. In the UK, it is known as Plymouth Pear after the city of Plymouth in Devon, where it was originally found in 1870 The Plymouth pear was one of the British trees to be funded under English Natures Species Recovery Programme.
Liquidambar acalycina, Chang’s sweet gum, is a species of flowering plant in the family Altingiaceae, native to southern China. Growing to 30–50 ft (9.1–15.2 m) tall and 20–30 ft (6.1–9.1 m) broad. It is a medium-sized deciduous tree with three-lobed maple-like leaves that turn red in autumn before falling. It is monoecious, meaning both male and female flowers appear on the same plant. The flowers are insignificant, yellow/green in colour, and are followed by small gum-balls that persist on the tree until winter. The wood exudes a sweet-smelling resin when pierced, giving the tree its common name.
Pyrus phaeocarpa, the dusky pear or orange pear, is a species of flowering plant in the family Rosaceae, native to the Loess Plateau of northern China. A wide tree reaching at most 7–8 m (23–26 ft) in height, it is hardy to USDA zone 5, or perhaps even zone 4. Its small yellow to brown fruit are edible, and its Autumn foliage is bright orange to orange-red, giving it good potential as an ornamental. Its chloroplast genome shows that it is closely related to Pyrus pashia, the wild Himalayan pear, and it is suspected to be a hybrid of P. betulifolia, the birchleaf pear, P. pyrifolia, the apple pear, and P. ussuriensis, the Manchurian pear.