Casuarina

Voucher:   Casuarina pauper  F.Muell. ex L.A.S.Johnson JAB179, JAB187

Family:  Casuarinaceae  Common name(s):  Black oak, belah

Habit:  Tree 5-15 m tall.  Distribution:  South-west Queensland, far west New South Wales, north-west Victoria and inland South Australia extending to southern inland Western Australia.

General features: Density 900 kg/m3 .   Heartwood absent or visually indiscernible from sapwood.

Microscopic features:

Vessels  Tangential vessel diameter: range 20-171 µm; mean 37 µm; SD 11 µm; average maximum 57-62 µm; n =  523 vessels.  Vessels per square millimetre: range 38-95 vessels per mm2;  n =   11 sampled areas.  Vessels solitary.  Perforation plates simple with prominent rim.  

*Fibres/tracheids   With numerous, distinctly bordered pits present.

Axial parenchyma   Banded axial parenchyma present.  Banded parenchyma unbroken.  Banded parenchyma further apart than rays and narrower than pores. 

Rays Rays 1-4 cells wide with uniseriate rays present (n = 288 rays).  Rays of uniform width and not wider than vessels.  Rays 10-18 per tangential mm (n =   12 sampled areas).  Ray height: range 44-408 µm; mean 180 µm; SD 65 µm; n =   223 rays.   Rays heterocellular.     

Helical thickenings  Present.

Physical and chemical tests:  Chrome azurol-s test negative.  

Notes:  Heartwood-dependent characters are not assessed for wood where heartwood is absent or visually indiscernible from sapwood until such time it can be reliably determined that heartwood is present.

* At this stage the key makes no distinction between fibres and tracheids as they are difficult to tell apart and there is some confusion in the wood anatomical literature as to their definitions in hardwoods (IAWA: 264). For example, the taxa for which this character was predominantly included - Myrtaceae A (Eucalyptus & Melaleuca) - contain numerous, conspicuous bordered pits that are both called fibre tracheids (Dadswell 1972: 21) and vasicentric tracheids (IAWA: 262).