Introduction:This topic is covered during the same lab period as "Woody Stems" and is a compliment to that lab.
To understand the three dimensional structure of wood, three different types of sections must be viewed: the cross-section and two types of longitudinal sections. A longitudinal section made perpendicular to the rays is a tangential section; one made parallel to the rays is a radial section.
Pine Wood: This wood is made up of parenchyma and only one type of treachery element - tracheids. The rays are typically one cell layer wide, however resin ducts lined with parenchyma cells run both vertically (through the axial system) and horizontally (through certain rays). Those rays with resin ducts are wider.
Oak Wood: This wood is made up of parenchyma, two types of treachery elements - tracheids, and vessel members, and a host of other types of cells that include fibers and various cells that are intermediate in structure between fibers and tracheids. You need to recognize parenchyma cells, vessel members, tracheids, and fibers. Some rays are many cell layers wide making them visible to the naked eye.