Continuous Fibers Prevent Structural Weakness

close up photograph of a knothole in a tree

Biological Strategy

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Prevent Fracture/Rupture

High force impact or stress can cause materials that comprise living systems to separate into two or more pieces (called fracturing) or to break or burst suddenly (called rupturing). For example, a scallop prevents structural failure from fracture because its shell is comprised of two materials of varying stiffness. When a crack moves from the scallop’s stiff material to the less stiff one, the latter reduces the force at the tip of the crack, thereby stopping it from spreading farther.

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Conifers and Others (Pines, Spruce, Gingko)

Clade Gymnosperms (“naked seeds“): Conifers, cycads, Gingko, gnetophytes

There are approximately 1,000 known species of Gymnosperms. These include well known needle-bearing plants like pines, firs, and spruce, as well as some with broad leaves like the Gingko and the gnetophytes. Instead of flowers, gymnosperms produce unenclosed (“naked”)seeds exposed on the surface of cone scales. Economically, conifers make up 45 percent of the world’s lumber production. The first gymnosperms evolved over 390 million years ago in the Paleozoic Era and dominated landscapes for a quarter of a billion years before the evolution and diversification of flowering plants.

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Knotholes in wood do not crack because the fibers around them are continuous.

“There has been relatively little attempt to produce an artificial analogue to wood because wood is cheap, lightweight, tough, moldable, and easily shaped. However, when a hole is drilled in timber, it weakens the structure. The tree, however, drills no holes, even though it must disrupt the trunk’s wood where a new branch pushes through. The fibers deform around a knothole, remaining continuous. George Jeronimidis of the Univ. of Reading Center for Biometrics is proposing to study how this can be used in fibrous composite materials.” (Courtesy of the Biomimicry Guild)

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