BISC 337 Lecture Notes - Lecture 21: Tracheid, Softwood, Dendrochronology

• School: Simon Fraser University
• Department: Department of Humanities Biological Sciences
• Course: BISC 337
• Professor: Aubrey Pearson

Document Summary

Structurally simple: cells of the axial system, tracheids, resin ducts, tracheids are arranged as neat radial files of cells, rays are narrow, single cell width. Growth rings (seen better in transverse section: visible due to differences in the density of the wood produced early & late in season, earlywood wide thin-walled cells latewood narrow thick-walled cells. Structure of wood: arrangement of vessels in angiosperm wood, type of vessels in wood, fibers in wood, wood axial parenchyma, wood rays, heartwood and sapwood, reaction wood, tension wood, compression wood. Variation in size of vessels in wood: medium sized vessels in a mass of fibers, vessels of two different size, vessels arranged in long radial groups. Very narrow vessels and fibers are abundant in late wood: early wood: maximum conduction, late wood: more strength, t. l. s. through fiber-rich late wood. Mar 4: axial parenchyma cells surrounding the vessels. B and e both shows large bands of axial parenchyma.