Ribbed Structure Provides Support

close up shot of green and dark brown plant

Biological Strategy

Water lily

Alexandra Ralevski

Image: Laitr Keiows / Wikimedia Commons / CC BY - Creative Commons Attribution alone

Prevent Buckling

When a living system undergoes compression to the extent that it causes structural damage, it results in buckling. For example, if a person pushes down on the top or the side of a paper cup, the cup’s wall will eventually give way, or buckle. Although a living system could add material to strengthen a structure, this requires expending precious energy. Instead, it must use energy and materials conservatively to avoid buckling, strengthening structures through careful placement of materials to resist, absorb, or deflect compressive forces. For example, instead of one long, tubular stem, some plants like bamboo have stronger nodes scattered along their stems. When compressed, these nodes keep the round stems from taking on an oval shape that weakens the structure and could result in buckling.

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Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

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The ribbed underside of the Amazon water lily provides structural support to keep the leaf afloat and sustain small loads.

Introduction

Many plants that grow near the banks of rivers will float their leaves on the surface, to allow their seeds to be carried downstream and pollinate other areas. In order to ensure a long trip, leaves that are able to float on the surface can ensure maximum sun absorption for . The larger a leaf is, the more surface area it can expose for photosynthesis, and the more aggressively it can compete with other leaves for space on the surface of the water. One of the most extreme examples of this is the leaves of the Amazon water lily, which float on the water of the Amazon river basin and grow up to several meters across. Its massive surface area allows it to maximize sun exposure, but also makes it more difficult to keep afloat and makes it susceptible to damage from animals that use the leaves as a means to get across the river. To cope with this, the Amazon water lily has a significant support system on the underside of its leaves, which allow it to sustain weights up to 70 pounds, while still remaining afloat.

The Strategy

Underneath each leaf is a ribbed, girder-like support structure that helps the leaf support small loads and hold a rigid shape, in order to maximize surface area exposure for photosynthesis. The structure consists of a main rib that runs along the center of the leaf, with additional ribs that radiate from the center and incrementally fork along the leaf. The ribs themselves are flat, wall-shaped structures, and the thickness of the ribs decreases towards the edge of the leaf. All of the ribs are filled with air, which increases their surface area, better distributing the total weight of the structure, helping to keep the leaf afloat. Neighboring ribs are connected to each other by a pattern of radial webbing forming loose concentric circles that emanate from the center of the leaf. This webbing provides additional structural support without adding much weight.

Image: Canon EOS 650d / Public Domain - No restrictions

Amazon Water Lily

Drawing of the underside of the Amazon water lily reveals intricate support structure

Image: Laitr Keiows / CC BY SA - Creative Commons Attribution + ShareAlike

Ribbed underside of Amazon water lily shows support structure

The Potential

The structural ribbing of an Amazon water lily could inspire new designs for floating platforms, emergency rafts, or small inflatable vessels. It could even be used to improve the stability or weight-bearing capacity of other structures, such as scaffolds or shelving.

Last Updated March 25, 2020

References

Book

The Private Life of Plants

BBC Books | 21/08/1995 | David Attenborough

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