Woody plants produce secondary growth from lateral meristems. Ray initials - small cells, orientated perpendicular to the axis of the stem. Sapwood -light colored wood just under the bark. It is filled with harden resins, gums, oils and does not conduct. It is harder, denser and more durable.
Knots are the bases of branches.
Each growth ring is actually a long cone stacked on top of each other. Tangential sections produce V-shaped bands Density is expressed as specific gravity . In Dicots extra wood with few vessels and many gelatinous fibers mostly made of cellulose. Unusual secondary growth Unusual behavior of vascular cambium vascular cambium in carrot roots produces large amounts of storage parenchyma rather than vascular tissue More than one cambium in beets the rings are produced by several concentric rings of vascular cambium Differential activity may not produce a uniform ring.