1. Longitudinal Parenchyma
Hardwood Cell Type
Longitudinal Parenchyma
Always present
Small & thin walled cells
m long
20-30 m diameter
Remain alive in sapwood (when functioning)
Function - storage
Simple pits between longitudinal parenchyma
Arrangement
Apotracheal
Paratrachel
Boundary

2. Hardwood longitudinal parenchyma
(Wilson and White)
longitudinal parenchyma

3. Longitudinal parenchyma
Grubbia sp.
Amburana cearensis

4. Longitudinal parenchyma
Apotracheal
Paratracheal
Boundary

5. (Hoadley)

6. (Hoadley)

7. (Hoadley)

8. Hardwood Cell Type Ray Parenchyma Procumbent Upright Always present
Height - few to many cells high 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
Procumbent
Upright

9. Hardwood Rays Transverse section view
Aspen Ash Red Oak

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

11. 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)

12. Tangential section
procumbent
upright

13. Radial section
upright
procumbent
(Hoadley)

14. Hardwood rays
Ray ends
Multiseriate ray ends
Uniseriate ray ends

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

16. Tyloses
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.
(Côté)

17. Tylosis formation
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)

18. Tyloses formation (White oak)
Sapwood
Heartwood
(The Wood Database)

19. Tyloses
(Butterfield, Meylan & Peszlen)