. Botany for high schools. Botany. 358 GENERAL MORPHOLOGY OF PLANTS trees of large size widely distributed over different parts of the world, especially the Northern Hemisphere. Many of these grow in great abundance in extreme northern latitudes where the winter season is very cold, while others occur in temperate and in subtropical countries where the heat of the season is often very great. Some of the trees of great size are the giant red woods {Sequoia) of the Sierra Nevada Mountains. Others are the pines, spruces, firs, balsams, larches, cypresses, cedars, hem- lock spruces, a^^bor vitae,
. Botany for high schools. Botany. 358 GENERAL MORPHOLOGY OF PLANTS trees of large size widely distributed over different parts of the world, especially the Northern Hemisphere. Many of these grow in great abundance in extreme northern latitudes where the winter season is very cold, while others occur in temperate and in subtropical countries where the heat of the season is often very great. Some of the trees of great size are the giant red woods {Sequoia) of the Sierra Nevada Mountains. Others are the pines, spruces, firs, balsams, larches, cypresses, cedars, hem- lock spruces, a^^bor vitae, etc. The yew or ground hemlock is an example of a shrub!jy form. The majority of the conifers have a straight excurrent trunk, with lateral rather subor- dinate branches, thus forming a large straight boll, making them especially valuable as timber trees, aside from the valuable quality of many of the woods. The branches in the pines, balsams, and some other trees, arise in apparent whorls on the main shoot, from lateral buds grouped just below the terminal bud. It is possible then to determine the age of the tree so far as the branches are retained over the lower part of the trunk. In the hemlock spruce, cedars, and some others the branches are more or less scattered along on the trunk. 526. The leaves are needle-like and quite long in the pines, shorter and more flattened in the spruces, and scale- like in the cedars, arbor vita^, etc. In the pines they are in clusters of two to five (rarely one in some western pines) at the end of a very short branch. wood-cells. (After Sachs.) r^^^ thw^ tWO kiuds of shootS developed each year, the long ones and the short ones. The long ones correspond in arrangement on the stem to the short ones and this is the reason they are so crowded on the stem as to. Fig. 342. Pinus sylvestris; longitudinal radial section through the wood of a rapidly growing branch; <:, b, cambial wood-cells (trache'des): a to e, older wood-cells (trache
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
