Tension Releases Seeds

small bright yellow flowers of a broom shrub open towards the sun

Biological Strategy

French broom

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Disperse Seeds

Plants disperse their seeds using a variety of mechanisms, including wind, rain, and attachment to animals. Seed dispersal can be important if plants growing too close together will compete for resources, such as nutrients and sunlight. Since plants are literally rooted in place, seed dispersal is also an important mechanism for expanding their range or reaching new environments.

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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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Seed pods of broom shrub disperse seeds via evaporative tension buildup and release.

Image: Franz Xaver / Wikimedia Commons /

Image: Jeffdelonge / Wikimedia Commons /

Image: Wikimedia Commons /

“Broom powers its explosions in exactly the opposite manner. Its launching energy comes not from an increase of liquid but from its evaporation. As a pod warms on a summer’s day, the side facing the sun dries faster than that in the shade. This sets up a tension in the pod which finally causes it to split suddenly into its two halves, catapulting its tiny black seeds in all directions as it does so.” (Attenborough 1995:16)

Last Updated October 23, 2016

References

Book

The Private Life of Plants

21/08/1995 | David Attenborough

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