Pyrus communis sativa
This entry is for the cultivated pear, which is widely grown as a fruit crop. The wild forms of the pear are all included under Pyrus communis since there are no significant differences in the way they are used[
In spite of their wide geographic distribution, the various species in the genus Pyrus are intercrossable without major incompatibility barriers. Also, the high morphological diversity and the lack of distinguishing characters among the species have been reported. Therefore, the classification of species in this genus is problematic and often confusing, giving different populations designated as different species by some authors. It is likely that, when the genus is reviewed, there will be several changes to the nomenclature[
Aria crenata (D.Don) Decne.
Cormus crenata (D.Don) Koehne
Crataegus excelsa Salisb.
Pyrus amphigenea Dostálek
Pyrus domestica (Borkh.) Borkh.
Pyrus sativa (DC.) C.Koch
Sorbus pyrus Crantz
Common Name: Pear
Pyrus communis sativa is a deciduous tree, sometimes armed, usually growing up to 15 metres tall but occasionally up to 30 metres[
]. The tree is often grafted onto dwarfing rootstocks and then is often no more than 5 metres tall.
The pear is one of the most popular and commonly cultivated tree fruits in the temperate and subtropical zones; it is widely grown, especially in places such as southern Europe, Australia, New Zealand and N. America.
Although no specific information has been seen for this plant, the seed of many species in the family Rosaceae are likely to contain cyanogenic glycosides. When injested, these compounds break down in the digestive tract to release cyanide. Used in small quantities in both traditional and conventional medicine, this exceedingly poisonous compound has been shown to stimulate respiration, improve digestion, and promote a sense of well-being[
]. It is also claimed by some to be of benefit in the treatment of cancer - though this claim has been largely refuted.
In larger concentrations, however, cyanide can cause gasping, weakness, excitement, pupil dilation, spasms, convulsions, coma and respiratory failure leading to death[
The levels of toxin can be detected by the level of bitterness:- sweet almonds, for example, contain only very low levels of it and are safe to eat in quantity, whilst bitter almonds (which are used as a flavouring in foods such as marzipan) contain much higher levels and should only be eaten in very small quantities. Great caution should be employed if the taste is moderately to very bitter[
A garden cultivar, probably derived from Pyrus communis, Pyrus cordata and Pyrus nivalis[
Not known in the wild.
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Pyrus communis sativa is a very cold-hardy plant, tolerating temperatures down to at least -20°c when dormant[
Prefers a good well-drained loam in full sun[
]. Grows well in heavy clay soils[
]. Tolerates light shade but does not fruit so well in such a position. Tolerates atmospheric pollution, excessive moisture and a range of soil types if they are moderately fertile, though plants can become chlorotic on very alkaline soils[
]. Established plants are drought tolerant[
The pear is widely cultivated for its edible fruit in temperate and subtropical areas. There are more than 6,000 named varieties with fruits differing in size, shape, colour, flavour, season of ripening etc. Differect cultivars can be selected to provide fruit from mid summer round to the spring of the following year.
This is the collective name for all the pear cultivars that have been derived from Pyrus communis, probably through hybridization with Pyrus cordata and Pyrus nivalis.
Where space is at a premium, or at the limits of their climatic range, pears can be grown against a wall. Most cultivars will grow well against a sunny south or west facing wall but, because of their relatively early flowering, they are not really suitable for north or east facing walls[
Most cultivars are not self-fertile and a number of cultivars have incompatible pollen, so care must be taken to ensure the provision of a suitable pollen partner[
Trees grow less well in grass, root secretions from the grass inhibiting the root growth of the pear[
Fruit - raw or cooked. The flavour ranges from rather harsh and astringent (mainly cultivars used for making alcoholic drinks or for cooking) through to soft, sweet, aromatic and very juicy. The best dessert fruits have an exquisite sweet flavour, usually with a very soft flesh, whilst cooking varieties have harder less sweet flesh[
The fruit is astringent, febrifuge and sedative[
A yellow-tan dye is obtained from the leaves[
A light brown dye is obtained from the bark[
The seeds contain 12 - 21% fatty oils[
The reddish-brown wood is fine grained, heavy, hard, tough, durable. It weighs 51lb per cubic foot[
]. An excellent timber, it is used by cabinet and musical instrument makers and for lathework[
]. When covered with black varnish it is an excellent ebony substitute[
Seed - best sown in a cold frame as soon as it is ripe in the autumn, it will then usually germinate in mid to late winter. Stored seed requires 8 - 10 weeks cold stratification at 1°c and should be sown as early in the year as possible[
]. Temperatures over 15 - 20°c induce a secondary dormancy in the seed[
]. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in light shade in a cold frame or greenhouse for their first year. Plant them out in late spring or early summer of the following year. The seed of pear cultivars will not usually breed true to type.