FNA: Pyrus vs. Pyrus cordata

Phenology

Flowering late Apr–early May; fruiting Aug–Sep.

Habitat

Moist soil at edge of wetlands

Elevation

200–300 m (700–1000 ft)

Distribution

Europe; Asia; n Africa [Introduced in North America; introduced also in Mexico, South America, Pacific Islands (New Zealand), Australia]

[BONAP county map]

MI; Europe; w Asia; n Africa [Introduced in North America]

[BONAP county map]

Discussion

Species ca. 25 (6 in the flora).

Pyrus communis is widely cultivated and naturalized in temperate and subtropical regions around the world. The evergreen pear, P. kawakamii, is widely cultivated, especially in California. This taxon has recently been included in P. calleryana (G. Cuizhi and S. A. Spongberg 2003), which is escaped in California. Some of the ornamental pear cultivars available in North America are selections of the oriental P. betulifolia Bunge, with fruits less than 1 cm diameter and leaves tomentose or at least slightly hairy proximally. Pyrus betulifolia is frequently used as a grafting stock. The willow-leaved pear, P. salicifolia Pallas, with densely silvery-pubescent leaves, pendent branches, and brown, pyriform pomes, is rarely cultivated in North America and is not known to escape. The Ussurian pear, P. ussuriensis Maximowicz, is less often cultivated and not known in North America as an escape; it is distinguished by persistent sepals on the fruit and spinulose-serrate leaf margins.

Pyrus may be divided into three groups (J. S. Challice and M. N. Westwood 1973; R. L. Bell 1990; K. Browicz 1993). Pyrus calleryana belongs to the Asian pea pear group. Pyrus pyrifolia belongs to the medium- to large-fruited Asian pears. Both P. communis and P. nivalis belong to the group of European species.

Although the cultivated fruits of apples and pears are easily distinguished, the wild pears and wild apples are sometimes quite similar. Pears differ from apples (Malus) by their hard glossy leaves, leaf margins with callused serrations, flower clusters with a central axis, and fruit with abundant stone or grit cells. The closely related quince (Cydonia oblonga) differs in its basally subcordate leaves that are abaxially tomentose and have entire margins, and its tomentose, pyriform pomes.

The identification of wild pears in North America is difficult. For more information see 4. Pyrus calleryana. The genus requires more study to resolve relationships, taxa, and hybrid origins.

(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.)

Key

1. Branches white-tomentose when young; leaf blades: abaxial surfaces densely whitish gray pubescent.	P. nivalis
1. Branches and leaf blades glabrous or glabrescent	→ 2
2. Leaf margins spinulose-serrate, surfaces brown-lanate when young; flowers 25–35 mm diam.; pomes subglobose.	P. pyrifolia
2. Leaf margins entire or crenulate, serrulate, crenate-dentate, obtusely serrate, or crenate, surfaces glabrous or brown-tomentose abaxially when young; flowers 15–35 mm diam.; pomes globose, subglobose, obovoid, ovoid, or pyriform	→ 3
3. Styles 2 or 3(or 4); pomes blackish brown or dark brown, brown, or yellow-brown (often with pale dots), subglobose, globose, or obovoid, 10–15(–22) mm diam	→ 4
3. Styles 3(–5); pomes yellowish, green, brown, or red (with or without pale dots), globose, subglobose, ovoid, or pyriform, 8–160 × 8–120 mm	→ 5
4. Sepals mostly persistent; pomes subglobose or obovoid, 15–22 mm diam.; styles 3(or 4).	P. serrulata
4. Sepals usually deciduous; pomes globose, 10–15 mm diam.; styles 2 or 3.	P. calleryana
5. Leaf margins densely ciliate when young; sepals persistent; petals (12–)13–15 mm; leaf blades ovate or suborbiculate to elliptic, bases broadly cuneate to almost rounded.	P. communis
5. Leaf margins eciliate or sparsely ciliate when young; sepals deciduous, sometimes persistent; petals 6–12 mm; leaf blades ovate, ovate-lanceolate, or suborbiculate, bases usually cordate, sometimes broadly rounded.	P. cordata