Internal Perforations Transport Nutrients

a microscopic image of sphagnum moss shows the inner cells of the leaves

Biological Strategy

Sphagnum moss

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Image: Казаков Александр Павлович / Wikimedia Commons / CC BY - Creative Commons Attribution alone

Store Chemical Entities

Chemical entities include elements such as carbon and metals, and compounds such as nutrients and proteins. Living systems must often store chemical entities–for example, for food or protection–temporarily or for long periods; the latter is synonymous with sequestration. Because chemical entities can react with other chemicals, living systems must store these entities so that they are stable and out of the way (for long-term storage) or readily available when needed (for temporary storage). An example of temporary storage is found in crustaceans such as crabs, which must shed their external skeletons as they grow. But first, a crab must absorb as much calcium carbonate from its shell as possible, storing the compound in its blood until the crab can use it to grow a new exoskeleton.

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Distribute Liquids

Liquids include water, as well as body fluids such as blood, gastric juices, nutrient-laden liquids, and more. To survive, many living systems must move such liquids within themselves or between locations. Because of their properties, liquids tend to disperse unless they are confined in some way. To address this, living systems have strategies to confine fluids for transport, and to overcome barriers such as gravity, friction, and other forces. Some of these same barriers also provide opportunities. Trees and giraffes face the same challenge: how to move fluids (water and blood, respectively) upward against gravity. But their strategies are quite different. The tree moves water using capillary action and evaporation, possibly due to water’s properties of polarity and adhesion. The giraffe’s tight skin provides pressure to assist in blood circulation. and keep blood from pooling in the legs.

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Mosses

Division Bryophyta (“moss plant”): Mosses, liverworts, hornworts

Bryophytes are one of the oldest groups of plants, appearing more than 500 million years ago in the Cambrian Period. Mosses are non-vascular, non-flowering, water-loving plants, often cushioning the floor of forests in dense mats. Unlike angiosperms or gymnosperms, mosses do not have fruits or seeds––they reproduce through spores. Currently, there are approximately 12,000 known species of mosses and their relatives. Sphagnum moss has been particularly useful to humans, as a key element in peat, and as a dressing for wounds in traditional cultures and along the battlelines of World War I.

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Sphagnum moss translocates nutrients via small perforations that connect the cells in the stem.

“The cation exchange is one explanation for why Sphagnum can grow in extremely poor habitats. Another factor is the ability to conserve nutrients. As the lower parts of the shoots are incorporated into peat, the plant faces the risk of losing essential nutrients and minerals. By tracer techniques (l4C, 32p) it has been shown that Sphagnum can translocate metabolites to the growing capitulum further down. This transport occurs internally and is dependent upon the plant being alive (Rydin and Clymo 1989). This is somewhat surprising, since Sphagnum mosses lack specialized conductive tissue. It is made possible since the cell ends in the stem are connected by small perforations (plasmodesmata) through which the transport occurs. Nitrogen is accumulated in new biomass, and it is likely that it is translocated internally in the same way (Aldous 2002).” (Rydin and Jeglum 2006:67)

Last Updated September 14, 2016

References

Book

The Biology of Peatlands, 2e (Biology of Habitats)

Oxford University Press | 15/09/2013 | Hakan Rydin

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