How to Identify Pau d'arco

Start with weight, because it is nearly diagnostic. Pau d'arco / ipe is extraordinarily heavy — among the densest woods you will handle — so a board that feels far heavier than its size suggests, and that may even sink in water, immediately points toward this group. A thumbnail makes essentially no impression; the surface feels glassy and hard, quite unlike ordinary decking woods.

Move to color and figure. The heartwood is a warm reddish-brown to orange-brown, often varying to olive- or darker walnut-brown with lighter and darker striping, and it darkens toward brown with exposure. The sapwood is sharply distinct and pale yellow to whitish. The grain is fine and even in texture, straight to interlocked, and on our sample distinct growth rings are visible in the cross-section — a helpful cue in this otherwise fine, uniform wood. Look also for a fine yellow-green powder, lapachol, deposited in the pores: rubbing a cut surface or wetting it can bring out this yellow dust, which is a strong indicator of ipe/pau d'arco and can stain a pale cloth.

Check the end grain. The wood is diffuse-porous with small pores, many plugged by the yellow lapachol deposits, arranged in the fine, tight structure that goes with its high density; there is no ring of large earlywood pores as in oak. Freshly worked ipe has only a faint, mild odor rather than a strong aromatic scent, so smell is of limited help beyond ruling out strongly scented woods.

The main confusions are with other dense reddish-brown tropical hardwoods. Cumaru (Brazilian teak) is also very hard and heavy but tends toward a more uniform tan-to-medium-brown with a waxy feel and a faint vanilla/cinnamon scent, and it lacks the yellow lapachol dust. Massaranduba is dense and red-brown but usually more uniformly red and without the striping. Jatoba (Brazilian cherry) is somewhat lighter in weight, more orange- to salmon-red, and shows a more pronounced grain. Genuine walnut, sometimes evoked by the 'Brazilian walnut' trade name, is far lighter in weight and softer, with a duller, more chocolate tone — the weight test alone separates the two. When density, reddish-orange-brown color, fine grain, and yellow lapachol powder occur together, pau d'arco / ipe is the strong answer.