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Encyclopedia Britannica - Main :: PAS-PER |
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PEAR (Pyrus communis) , a member of the natural order Rosaceae, belonging to the same genus as the apple (P.malus), which it resembles in floral structure. In both cases the so-called fruit is composed of the receptacle or upper end of the flower-stalk (the so-called calyx tube) greatly dilated, and en-closing within its cellular flesh the five cartilaginous carpels which constitute the " core " and are really the true fruit. From the upper rim of the receptacle are given off the five sepals, the five petals, and the very numerous stamens. The form of the pear and of the apple respectively, although usually characteristic enough, is not by itself sufficient to distinguish them, for there are pears which cannot by form alone be distinguished from apples, and apples which cannot by superficial appearance be recognized from pears. The main distinction is the occurrence in the tissue of the fruit, or beneath the rind, of clusters of cells filled with hard woody deposit in the case of the pear, constituting the " grit," while in the apple no such formation of woody cells takes place. The appearance of the treethe bark, the foliage, the flowersis, however, usually quite characteristic in the two species. Cultivated pears, whose number is enormous, are without doubt derived from one or two wild species widely distributed throughout Europe and western Asia, and sometimes forming part of the natural vegetation of the forests. In England,where the pear is sometimes considered wild, there is always the doubt that it may not really be so, but the produce of some seed of a cultivated tree deposited by birds or otherwise, which has degenerated into the wild spine-bearing tree known as Pyrus communis. The cultivation of the pear extends to the remotest antiquity. Traces of it have been found in the Swiss lake-dwellings; it is mentioned in the oldest Greek writings, and was cultivated by the Romans. The word " pear " or its equivalent occurs in all the Celtic languages, while in Slavonic and other dialects different appellations, but still referring to the same thing, are founda diversity and multiplicity of nomenclature which led Alphonse de Candolle to infer a very ancient cultivation of the tree from the shores of the Caspian to those of the Atlantic. A certain race of pears, with white down on the under surface of their leaves, is supposed to have originated from P. nivalis, and their fruit is chiefly used in France in the manufacture of Perry (see CIDER). Other small-fruited pears, distinguished by their precocity and apple-like fruit, may be referred to P. cord ata, a species found wild in western France, and in Devonshire and Cornwall
Karl Koch considered that cultivated pears were the descendants of three speciesP. persica (from which the bergamots have descended), P. elaeagrifolia and P. sinensis. J. Decaisne, who made the subject one of critical study for a number of years, and not only investigated the wild forms, but carefully studied the peculiarities of the numerous varieties cultivated in the Jardin des Plantes at Paris, refers all cultivated pears to one species, the individuals of which have in course of time diverged in various directions, so as to form now six races: (I) the Celtic, including P. cordata; (2) the Germanic, including P. communis, P. achras, and P. piraster; (3) the Hellenic, including P. parviflora, P. sinaica and others; (4) the Pontic, including P. elaeagrifolia; (5) the Indian, comprising P. Paschae; and (6) the Mongolic, represented by P. sinensis. With reference to the Celtic race, P. cordata, it is interesting to note its connexion with Arthurian legend and the Isle of Avalon or Isle of Apples. An island in Loch Awe has a Celtic legend containing the principal features of Arthurian story; but in this case the word is " berries " instead of " apples." Dr Phone visited Armorica (Brittany) with a view of investigating these matters, and brought thence fruits of a small berry-like pear, which were identified with the Pyrus cordata of western France. Cultivation.The pear may be readily raised by sowing the pips of ordinary cultivated or of wilding kinds, these forming what are known as free or pear stocks, on which the choicer varieties are grafted for increase. For new varieties the flowers
damp
In selecting young pear trees for walls or espaliers, some persons prefer plants one year old from the graft, but trees two or three years trained are equally good. The trees should be planted immediately before or after the fall of the leaf. The wall
bush
In the formation of the trees the same plan may be adopted as in the case of the apple. For the pear orchard a warm situation is very desirable, with a soil deep, substantial, and thoroughly drained. Any good free loam is suitable, but a calcareous loam is the best. Pear trees worked on the quince should have the stock covered up to its junction with the graft. This is effected by raising up a small mound of rich compost around it, a contrivance which induces the graft to emit roots into the surface soil, and also keeps the stock from becoming hard or bark-bound. The fruit of the pear is produced on spurs, which appear on shoots more than one year old. The mode most commonly adopted of training wall
horizontal
horizontal
The summer pruning of established wall or espalier -rail trees consists chiefly in the timely displacing, shortening back, or rubbing off of the superfluous shoots, so that the winter pruning, in horizontal training, is little more than adjusting the leading shoots and thinning out the spurs, which should be kept close to the wall and allowed to retain but two or at most three buds. In fan-training the subordinate branches must be regulated, the spurs thinned out, and the young laterals finally established in their places. When horizontal trees have fallen into disorder, the branches may be cut back to within 9 in. of the vertical stem and branch, and trained in afresh, or they may be grafted with other sorts, if a variety of kinds is wanted.Summer and autumn pears should he gathered before they are fully ripe, otherwise they will not in general keep more than a few days. The Jargonelle should be allowed to remain on the tree and be pulled daily as wanted, the fruit from standard trees thus succeeding the produce of the wall trees. In the case of the Crassane the crop should be gathered at three different times, the first a fortnight or more before it is ripe, the second a week or ten days after that, and the third when fully ripe. The first gathering will come into eating latest, and thus the season of the fruit may be considerably prolonged. It is evident that the same method may be followed with other sorts which continue only a short time in a mature state. Diseases.The pear is subject to several diseases caused by fungi. Gymnosporangium sabinae, one of the rusts (Uredineae) passes one stage ofits life-history on living pear leaves, forming large raised spots or patches which are at first yellow but soon become red and are visible on both faces; on the lower face of each patch is a group of cluster-cups or aecidia containing spores which escape when ripe. This stage in the life-history was formerly regarded as a distinct fungus with the name Roeslelia cancellata; it is now known, however, that the spores germinate on young juniper leaves, in which they give rise to this other stage in the plant's history known as Gymnosporangium. The gelatinous, generally reddish-brown masses of sporesthe teleutosporesformed on the juniper in the spring germinate and form minute sporessporidiawhich give rise to the aecidium stage on the pear. Diseased pear leaves should be picked off and destroyed before the spores are scattered and the various species of juniper on which the alternate stage is developed should not be allowed near the pear trees.Pear scab is caused by a parasitic fungus, Fusicladium pyrinum, very closely allied and perhaps merely a form of the apple scab fungus, F. dendriticum. As in .e the case of the apple disease it forms large irregular blackish blotches on the fruit and leaves, the injury being often very severe especially in a cool, damp
mycelium grows between the cuticle and the epidermis, the former being ultimately ruptured by numerous short branches bearing spores (con- idia) by means of which the disease is spread. As a pre- ventive repeated spraying with dilute Bordeaux mixture is recommended, during the flowering season and early development of the fruit. Similar spraying is recom- (From a specimen in the British Museum.) mended for pear-leaf blister Pear Scab (Fusicladium pyrinum). caused by Taphrina bullta, 1, Leaf showing diseased areas. which forms swollen areas on the 2, Section of leaf surface showing the also b leaves. e attacked yeas may spores or conidia, c, borne on long variety be at insect es a Thus stalks (conidiophores). the younger branches es are Thus the bre often injured by the pearl oyster
Pear-leaf Cluster-cups (Gymnosporangium sabinae). 1. Leaf showing groups of cups or aecidia. 2, Early stage of disease. 3, Cups. the early stages if the entrance of the caterpillars has been detected, a wire should be pushed into the hole. One. of the worst pests of pear trees is the pear midge, known as Diplosis pyrivora or Cecidomyia nigra, the females of which lay their eggs in the flower-buds before they open. The yellow maggots devour the seeds and thus ruin the crop. When deformed fruits are noticed they should be picked off and burned immediately. Species of aphides may be removed by tobacco infusion, soapsuds or other solutions. A gall mite (Phytoptus pyri) sometimes severely injures the leaves, on which it forms blistersthe best remedy is to cut off and burn the diseased leaves. The Alligator or Avocado Pear is Persea gratissima, a member of the natural order Lauraceae, and a native of the West Indies and other parts of tropical America. It is a tree of 25 to 30 ft. high and bears large pear-shaped fruits, green or deep purple in colour, with a firm yellowish-green marrow-like pulp surrounding a large seed. The pulp is much esteemed in the West Indies and is eaten as a salad, usually with the addition of pepper, salt and vinegar. The pulp contains much oil, which is used for lighting and soap-making, and the seeds yield a deep indelible black stain which is used for marking linen. Prickly pear is the popular name for species of Opuntia (see CACTUS). The name wooden pear is applied to the fruits of Xylomeluin (nat. ord. Proteaceae), an Australian genus of trees with very thick, woody, inversely pear-shaped fruits which split into two parts when ripe. End of Article: PEAR (Pyrus communis) If you wish, you can link directly to this article.
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