求梨子的英文介绍.
来源:学生作业帮助网 编辑:六六作业网 时间:2024/12/28 11:42:32
求梨子的英文介绍.
求梨子的英文介绍.
求梨子的英文介绍.
A pear is a pomaceous fruit produced by a tree of genus Pyrus. The English word pear is probably from Common West Germanic *pera, probably a loanword of Vulgar Latin pira, the plural of pirum, which is itself of unknown origin. It is known as nashpati in India See also Peorð. The place name Perry can indicate the historical presence of pear trees. The term "pyriform" is sometimes used to describe something which is "pear-shaped".
The pear is classified within Maloideae, a subfamily within Rosaceae. The apple (Malus ×domestica) which it resembles in floral structure, is also a member of this subfamily. 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 enclosing 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. Another major relative of the pear (and thus the apple) is the quince.
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. A major distinction is the occurrence in the tissue of the fruit, or beneath the rind, of clusters of lignified cells known as "grit" in the case of the pear, while in the apple no such formation of woody cells takes place. The appearance of the tree—the bark, the foliage, the type of inflorescence (i.e. form of the flower cluster)—is, however, usually quite characteristic in the two species.
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 can be cross-bred to preserve or combine desirable traits. The fruit of the pear is produced on spurs, which appear on shoots more than one year old.
Summer and autumn pears are gathered before they are fully ripe, while they are still green, but snap off when lifted. If left to ripen and turn yellow on the tree, the sugars will turn to starch crystals and the pear will have gritty texture inside. In the case of the 'Passe Crassane', long the favored winter pear in France, 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.
Pears are rich in Vitamin B2, Vitamin C, E1, copper, potassium and are 100% free from bad cholesterol. Pear juice is also known to be the first juice introduced to infants because of its hypoallergenic properties.