1 Hardwood Cell Type Always present Height - few to many cells high - 50  m to several cm Function - transport and storage Simple pits between ray parenchyma Semi-borderet pits with vessel elements Procumbent - blunt-ended cylinder, radially elongated (always present) Upright - rectangular, long axis vertical (sometimes present) Can be either homocellular or heterocellular Conformation can be: –uniseriate –multiseriate –aggregate Ray Parenchyma Procumbent Upright *

Hardwood Rays Transverse section view AspenAshRed Oak

3 Tangential and radial surfaces expose rays in many species to the naked eye. They give wood a certain aesthetic appeal. (Hoadley) Ray flecks Ray ends

4 On a tangential surface, a ray that consists of a single vertical series of cells – one cell wide ray – is a uniseriate ray. If is two cells wide, it is a biseriate ray, and if it is three or more cells wide it is multiseriate. (Hoadley)

5 procumbent upright Tangential section Radial section

6 upright procumbent (Hoadley) Radial section

Vessel Fiber Longitudinal parenchyma Ray parenchyma Fiber Model of water flow in hardwoods (Siau) The relative magnitude of the flows are indicated by the sizes and textures of the arrows. Longitudinal parenchyma pith bark

8 Bubble-like or membranous materials that fill or occlude the lumens of vessel elements. They result from the protrusion of a pit membrane and growth of protoplasm into the empty vessel lumen from a living parenchyma cell. The latter may be longitudinal or ray parenchyma. Tyloses (Côté)

Tylosis formation 9 Tyloses develop through the larger pits (min μm) at the time of heartwood formation in the tree. The heartwood of most temperate zone hardwoods contain tyloses in varying amounts. (Butterfield, Meylan & Peszlen)

Tyloses 10 (Butterfield, Meylan & Peszlen)