Invasiveness[edit] Callery pear fruit Winter fruit of Callery pear The Callery pear is an invasive species in many areas of eastern North America, outcompeting many native plants and trees.[2] In the northeastern United States, wild Callery pears sometimes form extensive, nearly pure stands in old fields, along roadsides, and in similar disturbed areas. 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. Callery pear is reported as established outside cultivation in 152 counties in 25 states in the United States.[6] 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] Smell[edit]
Posted on: Thu, 13 Mar 2014 04:46:11 +0000
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