page_title: Pinophyta
section_title: Tree ring structure
hierarchical_section_title: Pinophyta / Morphology / Tree ring structure
caption_attribution_description: English: Identifier: reportonrelation01fern (find matches) Title: Report on the relation of railroads to forest supplies and forestry&#160;: together with appendices on the structure of some timber ties, their behavior, and the cause of their decay in the road bed, on wood preservation, on metal ties, and on the use of spark arresters Year: 1887 (1880s) Authors: Fernow, B. E. (Bernhard Eduard), 1851-1923 Subjects: Forests and forestry Wood Preservation Railroads Ties Publisher: Washington, D.C.&#160;: Dept. of Agriculture, Forestry Division Contributing Library: U.S. Department of Agriculture, National Agricultural Library Digitizing Sponsor: U.S. Department of Agriculture, National Agricultural Library View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: Report of Forestry Division, Department of Agriculture. Text Appearing After Image: Photomicrograph by P. H. Dudley. Bell Bros., Washington, D. C. 380. Pinus Palustris, Miller&#160;; Long leaf Pine. Transverse Section x 100 Diameters. 45 Long leaved k Xellow Pine, Pinuspalustris, Mill. No. 3S0. The striking appearance of the structure of (Ins wood, as seen in thetransverse section, consists in the si rongly marked zones of differenl cellsin each layer of growth. At the present time satisfactory distinctivenames have not been given to these two Glasses of wood-cells or tracheitis.I shall use (he term thin - and t hick-walled tracheids to distinguish them.The former grow in the first part of the season, and the latter during thesummer; but the line of demarkation between tliem is sharp, not beinga gradual mergiug as in most of the other Conifers. In some trees, eachlayer is made up of about equal portions of the thin- and thick-walled tra-cheids, though these layers may vary in thickness from one-thirty-secondto one-fourth of an inch; in other trees, the layer of th Note About Images 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 not perfectly resemble the original work.
context_page_description: The Pinophyta, also known as Coniferophyta or Coniferae, or commonly as conifers, are a division of vascular land plants containing a single extant class, Pinopsida. They are cone-bearing seed plants, a subset of gymnosperms. All extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs. Examples include cedars, Douglas firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews. As of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, and 629 living species.
  Although the total number of species is relatively small, conifers are ecologically important. They are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but also in similar cool climates in mountains further south. Boreal conifers have many wintertime adaptations. The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing.
context_section_description: Tree rings are records of the influence of environmental conditions, their anatomical characteristics record growth rate changes produced by these changing conditions. The microscopic structure of conifer wood consists of two types of cells: parenchyma, which have an oval or polyhedral shape with approximately identical dimensions in three directions, and strongly elongated tracheids. Tracheids make up more than 90% of timber volume. The tracheids of earlywood formed at the beginning of a growing season have large radial sizes and smaller, thinner cell walls. Then, the first tracheids of the transition zone are formed, where the radial size of cells and thickness of their cell walls changes considerably. Finally, the latewood tracheids are formed, with small radial sizes and greater cell wall thickness. This is the basic pattern of the internal cel structure of conifer tree rings.
caption: The internal structure of conifer
exif: {}