Flora of North America species comparison

Pyrus communis is frequently cultivated and escapes to adjacent habitats, where it is sometimes common or even dominant. It includes more than a thousand cultivars, most of these being fruit (pomological) varieties. Ornamental forms with variegated leaves, dissected leaves, and unusual growth habits also occur. The taxon is of hybrid origin, and its parentage is thought to involve multiple species, including P. austriaca K. Kerner, P. nivalis Jacquin, P. pyraster, and P. syriaca Boissier. Pyrus pyraster is often treated as a wild species with smaller, rounder, and more sour fruit, yet it seems likely that wild pears fitting this description have originated from cultivated stock referable to P. communis, just as self-sown apples (Malus pumila) often have smaller, sour fruits. Recent authors are followed here in treating P. pyraster as a synonym.

The leaf margins of Pyrus communis are usually densely ciliate in flowering material, and this vestiture is retained to some extent in fruiting specimens. This characteristic, along with the broader fruiting pedicels, assists in distinguishing this species from P. cordata.

The high eating-quality pears were developed in the eighteenth or nineteenth century in northern Europe, although pears had been cultivated for centuries prior to that time. Currently, much of the cultivation in North America is in the Great Lakes area and on the Pacific coast. The highest production is in Europe (France, Germany, Switzerland), where most of the crop is used for making pear cider (perry); large-scale cultivation occurs also in Argentina, Australia, and Japan. The trees sometimes attain great age, and some in eastern North America, the French mission pears, persist today where planted 300 years ago on the sites of frontier forts in what was then a wilderness. Some of these old pears are of a type now no longer cultivated and have been identified as a significant germplasm resource.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Occasional plants that are considered possible hybrids involving either Pyrus calleryana or P. communis may actually belong here; in most cases, sufficient information is lacking to identify them with certainty. Report of this taxon for Michigan is based on both flowering and fruiting material from the same stand and on extensive notes and photographs.

The concept used here for Pyrus cordata is based largely on J. J. Aldasoro et al. (1996), who distinguished it from P. communis by its narrower fruit pedicels, 0.8–1.6 mm diameter versus 1.5–2.8 mm diam.; the authors have observed much variation in pedicel diameter in wild plants referable to P. communis, in which the pedicels of dry specimens are often less than 1.5 mm diam. Among the species occurring in Europe and North Africa, P. cordata is considered to be quite distinctive (Aldasoro et al.; J. S. Challice and M. N. Westwood 1973). The flowers are reported to have a particularly unpleasant odor.

(Discussion copyrighted by Flora of North America; reprinted with permission.)