. Barry's Fruit garden. Fruit-culture. THE STEM. 27 tant part in their development. In the old part it is dry, shrivelled, and seems incapable of taking any part in the process of vegetation, and this appears evident from the fact that trees often continue to flourish after the center, containing the pith, has begun to decay. Structure of the Stem. —The stem is composed of woody fibre and cellular tissue, a substance similar to the pith. The woody fibre is arranged in perpendicular lay- ers, and the cellular tissue in horizontal layers, running from the pith to the bark and connecting them. Th
. Barry's Fruit garden. Fruit-culture. THE STEM. 27 tant part in their development. In the old part it is dry, shrivelled, and seems incapable of taking any part in the process of vegetation, and this appears evident from the fact that trees often continue to flourish after the center, containing the pith, has begun to decay. Structure of the Stem. —The stem is composed of woody fibre and cellular tissue, a substance similar to the pith. The woody fibre is arranged in perpendicular lay- ers, and the cellular tissue in horizontal layers, running from the pith to the bark and connecting them. The mingling of these two systems gives to the surface of the cross section of a stem the beautiful veined or netted ap- pearance observable in fig. 3, which represents the cross- section of an oak branch. The perpendicular layers of woody fibre are most clearly observ- able when we cut a stem ver- tically; they are then easily separated from one another. Fig. 3.— section of a branch The layers, or plates of tissue ^^ ^^^' radiating from the center to the circumference of the stem and inner bark are called the medullary rays. Two of these are shown in fig. 2, marked by the dotted lines M. Growth of the Stem.—The stem of a tree is originally the extension of the cellular tissue of the seed. As soon as leaves are formed they organize new matter, which de- scends and forms woody fibres : the layers sent down from the first leaves are covered by those sent down from the next, and so on, one layer after another is pro- duced until the end of the season, when the leaves fall and growth ceases. A yearling tree has, therefore, a greater number of layers of woody fibre at the collar than at the top, and is, consequently, thicker; the second year the buds on the first year's growth produce shoots, and these. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may
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Keywords: ., bookcentury1800, bookdecad, booksubjectfruitculture, bookyear1883
