Pyrus castribonensis is a wild relative of the pear, (Pyrus communis L.) and as of 2017 has been preliminarily accepted as a distinct species in the Euro+Med PlantBase (http://ww2.bgbm.org/EuroPlusMed/PTaxonDetail.asp?NameCache=Pyrus castribonensis&PTRefFk=7300000).
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[
Pyrus castribonensis is a deciduous tree
The plant is used as a rootstock for the common pear (Pyrus communis) and is of potential value in breeding programmes
Pyrus castribonensis is a rare species, known from seven localities - one of them with less than 10 individuals, five of them with 10 to 20 individuals and one with more than 20. It is threatened by human activities, changes in land use, fires and grazing pressure. The taxonomic statuc of this species is uncertain, so the plant is classified as 'Data Deficient' in the IUCN Red List of Threatened Species(2013)[
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[
Southern Europe - Sicily
Near agricultural fields in clay soil; near Quercus suber woods, cultivated stands of Fraxinus excelsior and Olea europaea; margins of Pistacio-Rhamnetalia alaterni, Quercetalia ilicis and Prunetalia spinosae vegetation[
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Species in this genus generally prefer a good well-drained loam in full sun[
]. They usually grow well in heavy clay soils. They tolerate light shade but do not fruit so well in such a position, tolerate atmospheric pollution, excessive moisture and a range of soil types so long as they are moderately fertile[
]. Established plants are generally drought tolerant[
It is a wild relative of and potential gene donor to the cultivated pear, Pyrus communis[
The plant is used as a rootstock for the cultivated pear[
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.