Surface Tension Flings Spores

sunlight shines through a close up image of a fern

Biological Strategy

Ferns

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Distribute Solids

Solids include resources such as food, seeds, spores, and leaves, which living systems must sometimes move to accomplish various activities such as pollinating, feeding their young, or building shelters. To effectively distribute solids, living systems must use strategies appropriate to the sizes and types of solids and the media in which they exist (air, water, or another medium). This may entail strategies beyond simply holding and carrying solids. For example, some seeds are carried by the wind to new locations for germination. Others–like the burdock plant’s hooked seeds–cling to animal fur to be transported.

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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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Ferns

Class Polypodiopsida (“many footed appearance”): Ferns, horsetails, whisk ferns

Ferns are a class of plants that reproduce without flowers or seeds, but by spores. With over 10,500 known species, ferns are the second most abundant group of vascular plants after angiosperms (flowering plants). Though they can be found in a variety of habitats, ferns prefer moist, humid environments. Ferns first evolved in the Carboniferous Period about 360 million years ago. Today, ferns are grown for food, medicine, ornamental landscaping, and hold importance in culture and folklore. Several species can also remove pollutants from the atmosphere.

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The spores of one fern are launched from the sporangium using a mechanism based on surface tension and evaporation.

“A mechanism based on the surface tension of water is used by a fern that forcibly discharges its spores from the sporangium–evaporation decreases the volume of water and increases the surface curvature in a series of cuplike dead cells until the sustainable cohesion is exceeded; water then vaporizes and tension is relieved by a movement analogous to that involved in throwing a spear (Steward 1968).” (Vogel 2003:449)

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Last Updated August 18, 2016

References

Book

Comparative Biomechanics: Life's Physical World, Second Edition

Princeton University Press | February 24, 2021 | Steven Vogel

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