Tulip oak

Scientific name

Argyrodendron actinophyllum ssp. actinophyllum, A. trifoliolatum, A. peralatum. Family: Sterculiaceae.

Local names

Blush tulip oak, booyong, crowsfoot elm, blackjack (A. actinophyllum ssp. actinophyllum), brown tulip oak, highroot, stavewood, booyong, brown crowsfoot elm, brown oak, hickory (A. trifoliolatum), red tulip oak, red crowsfoot, red crowsfoot elm (A. peralatum)

Other tulip oaks include A. polyandrum, A. sp. aff. A. trifoliolatum, A. actinophyllum ssp. diversifolium, and A. sp. aff. A. peralatum.

Description and natural occurrence

The tulip oaks can grow up to 50 m in height. The bases of large trees are usually prominently buttressed. Leaves have white or silver on underside. A. actinophyllum ssp. actinophyllum and A. trifoliolatum occur in scrubs and rainforests along the east coast of Australia.

A. peralatum has a restricted distribution in North Queensland between Tully and Cooktown.

Wood appearance

Colour. Heartwood pink-brown for A. actinophyllum ssp. actinophyllum and brown for A. trifoliolatum. Sapwood not always readily distinguished. Heartwood pink to red-brown for A. peralatum, with whitish sapwood.

Grain. Grain is usually straight and open, sometimes interlocked or wavy and irregular producing some beautifully figured wood. Attractive figure on tangential face and large ray fleck on radial face are prominent features of the tulip oaks.

Wood properties

Density. 800-925 kg/m3 at 12% moisture content; approximately 1.1 to 1.3 m3 of seasoned sawn timber per tonne.

Strength groups. A. actinophyllum ssp. actinophyllum S3 unseasoned; SD3 seasoned; A. trifoliolatum S2 unseasoned, SD2 seasoned; A. peralatum S3 unseasoned, SD4 seasoned.

Stress grades. A. actinophyllum ssp. actinophyllum F8, F11, F14, F17 (unseasoned), F14, F17, F22, F27 (seasoned); A. trifoliolatum F11, F14, F17, F22 (unseasoned), F17, F22, F27, F34 (seasoned); A. peralatum F8, F11, F14, F17 (unseasoned); F11, F14, F17, F22 (seasoned), when visually stress graded in accordance with AS 2082:2000, Timber - hardwood - visually stress-graded for structural purposes.

Joint groups. J2 unseasoned; JD2 seasoned.

Shrinkage to 12% MC. 8.6% (tangential); 3.6% (radial) A. actinophyllyum ssp. actinophyllum. 9.0% (tangential); 3.3% (radial) A. trifoliolatum. 8.9% (tangential); 4.4% (radial) A. peralatum.

Unit shrinkage. 0.37% (tangential); 0.24% (radial) A. actinophyllum ssp. actinophyllum. 0.44% (tangential); 0.27% (radial) A. trifoliolatum. Unit shrinkage figures not available for A. peralatum.

Durability above-ground. Class 4 - life expectancy less than 7 years.

Durability in-ground. Class 4 - life expectancy less than 5 years.

Lyctine susceptibility. Untreated sapwood susceptible to lyctid borer attack.

Termite resistance. Not resistant.

Preservation. Difficult to impregnate with preservatives.

Seasoning. Careful drying under cover required to minimise degrade. Partial air-drying before kiln drying at low temperatures is recommended. Prone to collapse if dried too rapidly.

Hardness. Hard (rated 2 on a 6 class scale) in relation to indentation and ease of working with hand tools.

Machining. Not easy to work, but peels well. Moderately severe blunting effect on cutters. The cutting angle should be reduced to 20° when planing or moulding to avoid tearing the grain on quartered material.

Fixing. Nailing may require pre-boring.

Gluing. Glues satisfactorily.

Finishing. Will readily accept paint, stain and polish.

Uses

Construction. Flooring, green framing and plywood.

Decorative. Panelling, furniture, bent work, joinery, ornamental boxes, turnery and boat building.

Others. Handles, fishing rods.

Identification features

General characteristics

Sapwood. Not always easily distinguishable from the heartwood.

Heartwood. Pale light-brown to red-brown and dark brown.

Texture. Medium to coarse, grain mostly straight, occasionally interlocking.

Wood structure

Vessels. Solitary, and short radial chains of up to 4 cells or more, medium in size with uniform distribution. Vessel lines visible.

Parenchyma. Some paratracheal but mostly in irregularly spaced apotracheal bands.

Rays. Just visible to the naked eye, of two sizes, distinct and small. The larger rays are very visible and prominent on radial surfaces.

Other features

Burning splinter test. A match size splinter will burn (with some exudation and smoke) to a full white ash.

Ripple marks. Distinct in some species on smooth tangential surfaces.

Figure. Attractive figure on tangential dressed surfaces due to bands of parenchyma.

Further reading

Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, 'Forest trees of Australia', 5th edn, CSIRO Publishing, Collingwood Australia.

Bootle, K 2005, 'Wood in Australia: types, properties and uses', 2nd edn, McGraw-Hill, Sydney.

Hopewell, G (ed.) 2006, 'Construction timbers in Queensland: properties and specifications for satisfactory performance of construction timbers in Queensland, Class 1 and Class 10 buildings', books 1 and 2, Department of Primary Industries and Fisheries, Brisbane.

Ilic, J 1991, 'CSIRO atlas of hardwoods', Crawford House Press, Bathurst, Australia.

Standards Australia, 2000, 'AS 2082-2000: Timber - hardwood - visually stress-graded for structural purposes', Standards Australia.

Last updated 16 August 2010