Seeds Dispersed Across the Sea

a bright green seed pod, resembling a very large pea pod, hands from a branch against a lush green background

Biological Strategy

Sea-bean

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Protect From Excess Liquids

While water is essential to life, too much water or other liquids can overwhelm living systems. Excess liquids can, for example, decrease a living system’s access to oxygen, promote excessive bacterial or fungal growth, or strip away soil and nutrients. To prevent the accumulation of excess liquids, living systems must control the movement of liquids across their boundaries or surfaces. They do so using waterproofing materials or structures, slowing flow, and/or facilitating flow to move the liquid away. Plant leaves, for example, commonly have waxy surfaces comprised of water-repelling chemicals to keep water from engorging the leaves or facilitating bacterial and fungal growth.

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Manage Mechanical Wear

A living system is subject to mechanical wear when two parts rub against each other or when the living system comes in contact with abrasive components in its environment, such as sand or coral. Some abrasive components are a constant force, such as finger joints moving, while others occur infrequently, such as a sand storm moving across a desert. Living systems protect from mechanical wear using strategies appropriate to the level and frequency of the source, such as having abrasion-resistant surfaces, replaceable parts, or lubricants. For example, human joints like shoulders and knees move against each other all day, every day. To protect from mechanical wear, a lubricant reduces friction between the cartilage and the joint.

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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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The seeds of sea beans are dispersed great distances in water thanks to durable woody pods.

Sea beans are “gigantic compared with those of other members of the bean family, for they are about two inches across and carried in gigantic pods four feet long. When they first form, these pods, like other bean pods are green and soft, but as they ripen they become woody and heavy. Eventually, the pod falls into the river beside which the tree is growing and floats away. The pod breaks apart along thin grooves that run across it between the seeds. Each seed, with its own section of pod as packaging, then starts its own individual journey. Some may be stranded on a sand bank or a muddy beach within a few yards of their parents. But others regularly float down the whole length of the river, past the mangrove swamps around its estuary and on out to sea. By the time the seed gets washed up on a beach it may have lost every vestige of its pod, but even after a year at sea, it can still be viable. The sea-bean’s transport is so efficient that its seeds occasionally get carried far beyond the reach of the climate in which they can grow successfully.” (Attenborough 1995:21-22)

Last Updated October 16, 2016

References

Book

The Private Life of Plants

21/08/1995 | David Attenborough

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