Plant Poison Neutralizes Digestive Juices

photograph of white plants with the sky, mountains and water in background

Biological Strategy

Woolbearing dandelion

AskNature Team

Image: Aydin Hassan / Unsplash / Free non-commercial use

Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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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 poison produced by cotton grass protects them from lemmings by neutralizing digestive juices, leading to lemming starvation.

“The ability to produce poison may be the cause of one of the most celebrated, almost mythic, events in natural history – the mass suicide of the Norway lemming. These little hamster-like rodents of the Arctic tundra increase in numbers year after year until there is a population explosion, and then hordes of them are said to deliberately drown themselves.

“The cause of this extraordinary behaviour may be the fact, recently discovered, that when lemmings start to feed on the cotton grass and sedges that are their main food, the plants begin to produce a poison which neutralises the lemmings’ digestive juices. If the grazing is light, the plants stop doing this after about 30 hours, but if it is intense, as it is when the lemming population reaches its climax, they do so continuously. The effect on the lemmings is not only that they cannot digest their meals. Because they cannot, their bodies produce more and more digestive fluids, draining their physical resources and bringing them even closer to starvation. As a consequence, the more they eat the hungrier they get, and when having stripped the surrounding tundra they reach the edge of the sea or a lake, they swim out into it, in a frenzied attempt to find some food somewhere that will sustain them.” (Attenborough 1995:72)