The Hypothetical Relationship between Wood Properties and Suitability for Selfbows

Adapted from: George, N. (2024). Is Australian Flora Unsuitable for the Bow-and-Arrow? Economic Botany 78, 258–273.   🔗 Open access full text

About this figure

The suitability of any wood for selfbow construction is complex. It depends on a constellation of physical and mechanical properties — including grain consistency, growth-ring width, presence of reaction wood, knots, and the ratio of sapwood to heartwood — as well as the intended bow design, draw weight, and draw length. These factors are difficult or impossible to fully capture in a simple statistical model.

This figure illustrates how three commonly measured wood properties (specific gravity, modulus of elasticity, and modulus of rupture) correlate with woods that are empirically known to perform well as selfbow materials. The zones shown are hypothetical — they represent regions in the property space associated with historically favoured bow woods, not a guarantee of performance for any individual piece of wood.

The purpose of this figure is to serve as a starting point: to help bowyers and researchers identify candidate species worth exploring for bow making, and to consider which bow designs those properties might best suit. Field testing and stave evaluation remain essential.

See George (2024) Economic Botany for the underlying analysis.

Variance Explained

These bars show what proportion of the total variation in wood properties is captured by each axis. Together the two axes explain over 90% of the variation, meaning this 2-D plot is a highly faithful summary of the data.

PC1
PC2

PC1 (left→right): separates species by overall mechanical strength and density. Left = dense, stiff, strong. Right = light, flexible, weak.

PC2 (bottom→top): separates species by their MOR/MOE ratio — tensile strength relative to stiffness. Species near the top have the high MOR/MOE ratio that is the hallmark of excellent bow woods.

Colour & Highlight

All points start black. Click a button to colour that group and show its 90% confidence ellipse. Select as many groups as you like simultaneously. Switch between colouring by Wood Category or Continent. Click an active button to deselect it.

Species Finder

Search for a species by name or genus, then click a row to highlight that point on the biplot and see its properties. Click again to deselect. Sort the list by clicking the column headers.

Species Genus Common name

Selected Point

Hover over any point to see full details. Click a row in the Species Finder to highlight and select that species.

Hover a point for details.

Add Your Own Species

Enter mechanical properties to plot a species not in the dataset. Specific Gravity (SG) is wood density relative to water (typical range 0.3–1.2; higher = denser). MOE (Modulus of Elasticity, MPa) measures stiffness — higher values mean stiffer wood. MOR (Modulus of Rupture, MPa) measures tensile strength at failure — higher values mean stronger wood. Custom species appear as stars ★.