Callery Pear
Place of Origin: China and Southeast Asia
Place of Harm: Southeast, Texas, North to NY, West to Illinois
First Introduced: 1909
Harms: native plants, summer scents
Other Names: Bradford pear, Aristocrat pear, Chanticleer pear (all cultivars)
Taxonomy: Rosales, Rosaceae
Callery Pear is a deciduous tree that was first introduced to Harvard’s Arnold Arboretum. It was later introduced again in 1916 to prevent the fire blight (Erwinia amylovora) that was devastating common pears (Pyrus communis) and thus the US pear industry. In the 1950’s, many cultivars were developed due to the tree’s ornamental value. It grows up to 30 ft tall and is Callery pears are highly resistant to diseases, but are often killed by storms or frost. With a lifespan of <25 years, they can be found in old fields, roadsides, and in lawns. They prefer full sun and dry to medium soils, and can survive partial shade and all types of soils. The problem with Callery pear is that it is aggressive and crowds out native species, which are pushed out by the lack of sunlight, water, space, and nutrients. It produces large amounts of seeds spread by birds and small mammals; trees grow fast and lack insect/disease enemies. In the summer, trees have an unpleasant smell similar to bleach or chlorine. The branches point upwards, have weak structure and split in storms or wind. Callery pear can be controlled with hand pulling; seedlings can be pulled out when soil is moist. Girdling can also be used; cut through the bark 6” above the ground. Cut-stump method is used for large and medium trees; plants should be cut down with a chainsaw and stumps applied with a systemic herbicide (glyphosate or triclopyr). Callery pear spreads with vegetative propagation and seeds, which are spread in bird droppings. Plants begin flowering at three years; flowers appear in April-May (and require pollination), before leaves emerge; fruits appear from May to July and mature August to October. Each fruit contains 2-6 seeds with 50% germination. This tree is one of the first to leaf in in the early spring and one of the last to leaf out in late autumn; the autumn leaves appear in vibrant red shades. Similar native species include Pacific crabapple (Malus fusca). Callery pear is planted as an ornamental with white summer flowers and bright red to maroon leaves in the fall. The berries are consumed by birds. Pear wood in general is of a high quality, used for woodwinds and furniture. It is used as a backyard tree. Each individual cultivar is not invasive; the interbreeding between cultivars is what causes the abundance of plants. Even now, new cross-cultivars are being created with the different combinations of cultivars in different areas. “Pyrus” is a loanword from vulgar latin “pirum”, meaning fruit. It is named after Joseph-Marie Callery, who sent the trees to Europe from China in the 1800’s.
Place of Origin: China and Southeast Asia
Place of Harm: Southeast, Texas, North to NY, West to Illinois
First Introduced: 1909
Harms: native plants, summer scents
Other Names: Bradford pear, Aristocrat pear, Chanticleer pear (all cultivars)
Taxonomy: Rosales, Rosaceae
Callery Pear is a deciduous tree that was first introduced to Harvard’s Arnold Arboretum. It was later introduced again in 1916 to prevent the fire blight (Erwinia amylovora) that was devastating common pears (Pyrus communis) and thus the US pear industry. In the 1950’s, many cultivars were developed due to the tree’s ornamental value. It grows up to 30 ft tall and is Callery pears are highly resistant to diseases, but are often killed by storms or frost. With a lifespan of <25 years, they can be found in old fields, roadsides, and in lawns. They prefer full sun and dry to medium soils, and can survive partial shade and all types of soils. The problem with Callery pear is that it is aggressive and crowds out native species, which are pushed out by the lack of sunlight, water, space, and nutrients. It produces large amounts of seeds spread by birds and small mammals; trees grow fast and lack insect/disease enemies. In the summer, trees have an unpleasant smell similar to bleach or chlorine. The branches point upwards, have weak structure and split in storms or wind. Callery pear can be controlled with hand pulling; seedlings can be pulled out when soil is moist. Girdling can also be used; cut through the bark 6” above the ground. Cut-stump method is used for large and medium trees; plants should be cut down with a chainsaw and stumps applied with a systemic herbicide (glyphosate or triclopyr). Callery pear spreads with vegetative propagation and seeds, which are spread in bird droppings. Plants begin flowering at three years; flowers appear in April-May (and require pollination), before leaves emerge; fruits appear from May to July and mature August to October. Each fruit contains 2-6 seeds with 50% germination. This tree is one of the first to leaf in in the early spring and one of the last to leaf out in late autumn; the autumn leaves appear in vibrant red shades. Similar native species include Pacific crabapple (Malus fusca). Callery pear is planted as an ornamental with white summer flowers and bright red to maroon leaves in the fall. The berries are consumed by birds. Pear wood in general is of a high quality, used for woodwinds and furniture. It is used as a backyard tree. Each individual cultivar is not invasive; the interbreeding between cultivars is what causes the abundance of plants. Even now, new cross-cultivars are being created with the different combinations of cultivars in different areas. “Pyrus” is a loanword from vulgar latin “pirum”, meaning fruit. It is named after Joseph-Marie Callery, who sent the trees to Europe from China in the 1800’s.
Essential Question
"Could a genetically engineered invasive species potentially be used in warfare?"