Читать книгу The Pears of New York - U. P. Hedrick - Страница 19

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Pome-fruits are all woody plants, shrubby or tree-like, of which the pear is always a tree. The value of the variety and the recognition of it usually depend on characters of the fruits, but the trees are nearly as distinct as the fruits, are always helpful in identification, and in the absence of fruit must be relied upon to identify a variety. Also, and even more important, the pear-grower must know whether the plant is manageable in the orchard, for which purpose he must have a description of the chief characters of the tree.

Size and habit of tree.—Size of tree is a very reliable character to determine varieties of pears. The Winter Nelis pear is dwarf as compared with other pears. Size varies greatly with environment, it must be remembered in using this character. The terms large, small, and medium are commonly used to designate size. Vigor, which may be defined as internal energy, must not be confused with size. Small trees may be as vigorous as large ones.

The term habit of growth, as used by pomologists, has reference to the form of the top. In describing the tops of pear-trees a number of self-explanatory terms are used, such as pyramidal, upright-spreading, drooping, tall, low, dense, open-topped, and round-topped. Many if not most varieties of pears may be told by the form of the top. One can tell Bartlett or Clapp Favorite at a glance by their upright branches; as one can, also, Beurré d’Anjou and Beurré Superfin by their wide-spreading branches; or Winter Nelis pear by its drooping branches. Depending upon the form of the top, a variety is easy or difficult to manage in an orchard.

Constitutional characters.—Hardiness, productiveness, susceptibility to pests, adaptability to diverse soils and climates are vaguely supposed to be dependent on the constitution of the tree. Pomologists very generally refer to these characters as constitutional. They speak of the constitution as the aggregate of the vital powers of a variety.

Horticulturally, hardiness is ability to withstand cold. Obviously, hardiness is of utmost importance in characterizing the value of a variety to the pear-grower, and degree of hardiness is of some use in identifying pears. Bartlett and Beurré Bose are relatively tender to cold, Tyson is hardy, and Flemish Beauty is very hardy. Less important, but still of some importance, is the ability to withstand heat, a character possessed in varying degrees by varieties of pears.

Productiveness, age of bearing, regularity of bearing, certainty of bearing, and longevity are constitutional characters that must be noted in full descriptions. All help to determine the value of a variety, and all aid more or less in classification. For most part, these are inherent characters and are influenced but little by environment.

The degree of susceptibility of a variety to fungous diseases and insect pests is a valuable cultural character, but has little use in identifying or classifying pears. There are great variations in varieties of pears to the dreaded pear-blight: Bartlett, Beurré Bose, Beurré d’Anjou, and Clapp Favorite are among the varieties most susceptible; Kieffer, Seckel, and Winter Nelis are among those least susceptible to blight. Kieffer and related hybrids are somewhat immune to San Jose scale, but are very susceptible to psylla. Flemish Beauty and White Doyenné are so badly attacked by the scab-fungus that it is almost impossible to grow them in eastern America.

Some of these constitutional characters are much modified by care and environment, as all are more or less. Care and local environment often make it possible to grow varieties in special localities, although some varieties are inherently adapted to a greater number of diverse conditions than others. Bartlett, Seckel, and Kieffer have in common as one of their most valuable characters adaptability to a great diversity of soils and climates.

Trunk and branch.—The trunk does not count for much in descriptions of varieties. The height of the trunk usually depends on the whims of the pruner. Whether stout or slender is sometimes noteworthy. The bark may be smooth or shaggy. Color of bark is often a valuable diagnostic character, especially in young trees. Many if not most varieties of pears can be identified in nursery rows by an expert nurseryman from the color of the bark. Seckel, Sheldon, and Beurré d’Anjou have remarkably distinctive color as young trees.

The branches of pear-trees are often reliable guides in identifying varieties in orchard or nursery, especially when trees are leafless and fruitless. The twisting, drooping branches of Winter Nelis serve to identify that variety at any time. The zigzag branches of Beurré d’Anjou and Bloodgood are typical. The branches of Beurré Superfin are rough and shaggy. Those of Dorset and Fox are slender. The branches of several well-known pears are spiny. A glance through the technical descriptions in Chapter IV shows that branches and branchlets are variously colored. The branchlets may be stout or slender, long-jointed or short-jointed, pubescent or glabrous, straight or zigzag. The angle at which branchlets are set is often characteristic. The epidermis may be smooth or covered with scarf-skin. Lastly, the size, shape, color, number, and position of the corky cells or lenticels on young wood is most important in identifying trees after leaves have fallen.

Leaf-buds and leaves.—Size, length, and shape of leaf-buds are helpful in identifying varieties when the trees are dormant. There is considerable difference in the length of buds of different varieties, and they may vary in thickness; some are plump, others are slender. The shape can usually be described as acute, pointed, obtuse, or conical. If the bud lies close to the twig, it is said to be appressed; if it stands from the twig at a considerable angle, it is free. In some varieties the leaf-scar is conspicuous; in others, it is inconspicuous.

While leaves vary much in accordance with the condition of the plant which bears them, yet they offer a number of valuable distinguishing characters. It is important in making use of leaves to take only those borne on free-growing twigs, as those growing on luxuriant water-sprouts on the one hand, or on slow-growing spurs on the other are seldom typical.

The size of the leaf is a most valuable determinant of varieties of pears. Length and breadth should be given in figures. The shape should be depicted in carefully chosen words. The body of the leaf is usually ovate or oval, but these shapes must nearly always be modified by broad or narrow, long or short. The apex requires a descriptive word or two; as, taper-pointed, acute, or obtuse. Thickness and texture are sometimes noteworthy. The texture is usually described as stiff, leathery, or pliant. Sometimes the leaves are flat; sometimes folded upward, and rarely they are folded downward. The color of both the upper and lower surfaces is often important; and the amount of pubescence, if present, must always be noted on the two surfaces. The autumnal tint is a marked characteristic in some varieties. The margins offer valuable evidence for identification in the character of the serrations which are usually distinct in a variety. Sometimes glands and hairs are found on the margins, in which case they are usually noteworthy. The time of appearance and the fall of leaves are life events that distinguish some varieties. Leaves are many in some sorts; few in others. The length, thickness, color of the petiole and whether it is smooth, pubescent or channeled are usually worth noting. The presence and the size and color of stipules are often important enough to record. The petioles of pear leaves are larger and slenderer than those of the apple, and the foliage of a pear-tree has something of the tremulous habit of the aspen and other poplars. The leaves have a gloss that distinguishes them at once from those of the apple-tree. As a rule, the foliage of the pear drops earlier in the autumn than that of the apple.

When the leaves of pears open in the spring they are folded along the midrib, and are covered with snow-white wool, but at full maturity no trace of this woolly covering remains. The amount and texture of this covering on the leaves of different varieties vary greatly, although it is doubtful if this character is of much use for taxonomic purposes.

Flower-buds and flowers.—It is not possible to distinguish flower-buds from leaf-buds by their external appearance as certainly as might be wished for the purposes of ascertaining what the crop will be and that pruning and budding may be done more intelligently. As a rule, however, the flower-buds are larger, plumper, and have a blunter point. The flower-buds are much like leaf-buds in color—usually a dark brown. They may be readily told by their contents when examined under a microscope. Time of opening is a mark of distinction with varieties that bloom very early or very late, but the flowers of most varieties of pears open at approximately the same time.

The flowers of pears give small opportunity to identify varieties but are useful. The petals in most of the flowers of varieties of P. communis meet or lap at the widest point, which is a short distance from the point of attachment. Occasionally a variety has the petals widely separated. Easter Beurré, Vermont Beauty, and Dana Hovey are examples of varieties with widely-separated petals. Round and broadly-oval petals meet or lap, long narrow petals are usually separated. The size, shape, and color of the petals offer the best means of identification from flowers. The length, thickness, and amount and kind of pubescence on the styles may distinguish varieties. The styles of the Howell pear are abnormally short. The number of flowers in a cluster, and whether the cluster is dense or loose are important. The character of the fruit-spurs is nearly always noteworthy. The calyx-tubes, calyx-lobes, and pedicels differ materially. These structures in the flower, while offering decisive evidence in identification, are seldom used by pomologists because character of plant and fruit may be studied during a much longer time and are of greater cultural importance. In the blooming season, length, diameter, and the pubescence of stamens may be noted, but much more important taxonomically is the position of the stamens on the calyx-tube in the mature fruit. These organs, or remnants of them, persist in the ripened fruits, as will be noted in the discussion of characters of the fruit. Lastly, some varieties may be told during the blooming season by the distribution of the blossoms on the tree. The flowers of many varieties are borne on the periphery of the tree, and give the plant an aspect by which one may recognize the variety at once.

If a variety is not noteworthy in the characters for which the fruit is grown—those which appeal to the senses of taste and sight—it has small chance of being cultivated long or widely. Hence, especial attention is paid to descriptions of the fruit. Some pomologists describe varieties only from the fruit, saying little or nothing about the plant.