''Pyrus calleryana'', or the Callery pear, is a species of
pear
Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the family Rosaceae, bearing the p ...
tree
native
Native may refer to:
People
* Jus soli, citizenship by right of birth
* Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory
** Native Americans (disambiguation)
In arts and entert ...
to China and Vietnam,
in the family
Rosaceae
Rosaceae (), the rose family, is a medium-sized family of flowering plants that includes 4,828 known species in 91 genera.
The name is derived from the type genus ''Rosa''. Among the most species-rich genera are ''Alchemilla'' (270), ''Sorbus ...
. It is most commonly known for its
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
'Bradford' and its offensive odor, widely planted throughout the United States and increasingly regarded as an
invasive species
An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...
.
''Pyrus calleryana'' is
deciduous
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...
, growing to tall, often with a conical to rounded crown. The
leaves
A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
are oval, long, glossy dark green above, on long pedicels that make them flash their slightly paler undersides in a breeze. The white, five-
petal
Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...
ed
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s are about in diameter. They are produced abundantly in early spring, before the leaves expand fully.
The
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
s (which are often assumed to be inedible due to their abundant, cyanide laced seeds) of the Callery pear are small (less than in diameter), and hard, almost woody, until softened by
frost
Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a gas) ...
, after which they are readily taken by birds, which disperse the
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s in their droppings. In summer, the shining
foliage
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, s ...
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
Fire blight, also written fireblight, is a contagious disease affecting apples, pears, and some other members of the family Rosaceae. It is a serious concern to apple and pear producers. Under optimal conditions, it can destroy an entire orchard ...
. 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
Joseph-Marie Callery
Joseph-Gaëtan-Pierre-Maxime-Marie Callery or Giuseppe Gaetano Pietro Massimo Maria Calleri in Italian form (25 June 1810 – 8 June 1862) was an Italian-French Roman Catholic missionary who travelled into Southeast Asia where he studied Chinese an ...
(1810–1862), a
sinologue
Sinology, or Chinese studies, is an academic discipline that focuses on the study of China primarily through Chinese philosophy, language, literature, culture and history and often refers to Western scholarship. Its origin "may be traced to the e ...
who sent specimens of the tree to Europe from China.
Cultivation
Numerous
cultivars
A cultivar is a type of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and when Plant propagation, propagated retain those traits. Methods used to propagate cultivars include: division, root and st ...
of Callery pear are offered commercially, including 'Aristocrat', 'Autumn Blaze', 'Bradford', 'Capital', 'Chanticleer' (also known as 'Cleveland Select'), 'New Bradford', 'Redspire', and 'Whitehouse'.
File:Bradford 9288.JPG, alt=Cultivated Callery pears in flower
File:2014-11-02 14 11 35 Bradford Pear during autumn along Hunters Ridge Drive in Hopewell Township, New Jersey.jpg, Autumn color
File:2014-11-02 12 22 20 Bradford Pear foliage during autumn along Scotch Road in Ewing, New Jersey.JPG, Autumn color
In the United States
The trees were introduced to the U.S. by the
United States Department of Agriculture
The United States Department of Agriculture (USDA) is the United States federal executive departments, federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, ...
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
Claudia Alta "Lady Bird" Johnson (''née'' Taylor; December 22, 1912 – July 11, 2007) was First Lady of the United States from 1963 to 1969 as the wife of President Lyndon B. Johnson. She previously served as Second Lady from 1961 to 1963 when ...
promoted the tree in 1966 by planting one in downtown Washington, D.C. ''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."
In much of North America these cultivars, particularly 'Bradford', are widely planted as
ornamental trees
Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that i ...
. 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
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
s 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
Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Semen i ...
.
[''Pyrus calleryana'' at Floridata]
/ref> According to extension specialist Kelly Oten of North Carolina State University
North Carolina State University (NC State) is a public land-grant research university in Raleigh, North Carolina. Founded in 1887 and part of the University of North Carolina system, it is the largest university in the Carolinas. The universit ...
, the smell attracts flies
Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
which are the primary pollinator
A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains.
Insects are the maj ...
s rather than bees. At the latitude of Pittsburgh, Pennsylvania, the trees often remain green until mid-November, 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.
As an invasive species
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. 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.
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
Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcrossing and allogamy. It is contrasted with separation of sexes among individuals ...
, 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), 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
Thorn(s) or The Thorn(s) may refer to:
Botany
* Thorns, spines, and prickles, sharp structures on plants
* ''Crataegus monogyna'', or common hawthorn, a plant species
Comics and literature
* Rose and Thorn, the two personalities of two DC Com ...
.
Callery pear is reported as established outside cultivation in 152 counties in 25 states in the United States. 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. 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.
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
Pruning is a horticultural, arboricultural, and silvicultural practice involving the selective removal of certain parts of a plant, such as branches, buds, or roots.
The practice entails the ''targeted'' removal of diseased, damaged, dead, ...
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.
File:CalleryPearC.JPG, alt=Fruit
File:Callery Pear Fruit.JPG, In winter, alt=Fruit in winter
Uses
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.[Ohio State Universit]
''Pyrus calleryana''
Pear wood is also among those preferred for preparing woodcuts
Woodcut is a relief printing technique in printmaking. An artist carves an image into the surface of a block of wood—typically with gouges—leaving the printing parts level with the surface while removing the non-printing parts. Areas that ...
for printing, either end-grained for small works or side-grained for larger.[Escher, M.C. The Graphic Work of M. C. Escher. Pub: Oldbourne Book Co. London. 1961. page 9]
Callery pear has been used as rootstock
A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to a ...
for grafting
Grafting or graftage is a horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion () while the lower part is called the rootstock. The succ ...
such pear cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
s 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
Frank Nicholas Meyer (30 November 1875 – 2 June 1918) was a United States Department of Agriculture explorer who traveled to Asia to collect new plant species. The Meyer lemon was named in his honor.
Biography
He was born Frans Nicolaas Meij ...
, plant explorer for the US Department of Agriculture
The United States Department of Agriculture (USDA) is the United States federal executive departments, federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, ...
, commonly known for the discovery of the Meyer lemon
''Citrus'' × ''meyeri'', the Meyer lemon (), is a hybrid citrus fruit native to China. It is a cross between a citron and a mandarin/pomelo hybrid.
Mature trees are around tall with dark green shiny leaves. The flowers are white with a purp ...
, for agricultural experimentation, pre-dating recognition in the 1950s of the species' potential as an ornamental plant.
References
External links
Plant Invaders of Mid-Atlantic Natural Areas
{{Authority control
Naturalized trees of Alabama
Pears
calleryana
Taxa named by Joseph Decaisne