Myrtaceae B (Corymbia)

Genus: Corymbia

Vouchers:   C. terminalis JAB143, JAB156, JAB160, C. aparrerinja JAB157

Family:  Myrtaceae

General features:   Density 900-1100 kg/m3 .   Heartwood brown or red and visibly distinct from sapwood.   Gum deposits present and visible on C. terminalis, absent on C. aparerrinja. 

Microscopic features:

Vessels  Tangential vessel diameter: range 20-141 µm; mean 71 µm; SD 30 µm; average maximum 66-129 µm; n =  303 vessels.  Vessels per square millimetre: range 13-79 vessels per mm2;  n = 14 sampled areas.  Solitary vessels occur with radial multiples (although often multiples are more oblique and tend towards the tangential direction).  Perforation plates simple without prominent rim.  Vessel to vessel pits vestured. 

Axial parenchyma  Axial parenchyma paratracheal and confluent to banded.  Marginal bands present.  Abundant white deposits occur in axial parenchyma cells of C. aparerrinja ; these white deposits delineate the parenchyma bands on the endgrain surface. 

Rays Rays 1-3 cells wide with uniseriate rays present (n = 517 rays).  Rays of uniform width and not wider than vessels.  Rays 3-18 per tangential mm (n =  33 sampled areas).  Ray height: range 33-252 µm; mean 108 µm; SD 38 µm; n =  399 rays.   Rays heterocellular or homocellular?   Tyloses present in heartwood.

Helical thickenings  Absent.

Physical and chemical tests:  Chrome azurol-s test negative.   Heartwood fluorescence weakly positive (weak pink) to positive.  Froth test weakly positive to positive.   Ethanol extract fluorescence absent.  Ethanol extract colourless or discoloured.  Water extract discoloured.   Water extract fluorescence absent.

Notes:  

Notes:  Corymbia is distinguished from Eucalyptus and Melaleuca by the presence of vessels in radial multiples, marginal bands of parenchyma, and few and indistinctly bordered pits.  Absence of tyloses is not diagnostic and their presence is recorded only where they are abundant in heartwood (IAWA 1989: 261).