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As for the “fall colors…..”

September 24, 2009

“An optimist tells me to open my eyes and look at the world and see how beautiful it is in the sunshine, with its mountains, valleys, rivers, plants, animals and so on. But is the world, then, a peep-show? These things are certainly beautiful to behold, but to be them is something quite different.” —Arthur Schopnehauer

The reason of my perfect ease
In the society of trees
Is that their cruel struggles pass
Too far below my social class
For me to share them or be made
For what I am and love afraid.

—Robert Frost

The name—of it—is “Autumn”—
The hue—of it—is Blood—
An Artery—upon the Hill—
A Vein—along the Road—

Great Globules—in the Alleys—
And Oh, the Shower of Stain—
When Winds—upset the Basin—
And spill the Scarlet Rain—

It sprinkles Bonnets—far below—
It gathers ruddy Pools—
Then—eddies like a Rose—away—
Upon Vermilion Wheels—

—Emily Dickinson (Autumn 1862)

allelopathy, n. Botany. The deleterious process by which one organism influences others nearby through the escape or release of toxic or inhibitory substances into the environment: usu. restricted to such interaction between higher plants. 1957 H. Martin. Chem. Aspects Ecol. ii. 11 It would seem unnecessary to go to the extreme of Molisch, who coined the word ‘allelopathy’ from the reciprocal influence of higher plants. 1961 Symp. Soc. Exper. Biol. XV. 242 There is a type of allelopathy which follows from the movement of metabolic products from one species into another. ibid. 243 Perhaps the term ‘allelopathy’ should be extended to include the manifold mutual effects of metabolic products of both plants and animals. 1974 E.L. Rice. Allelopathy i. 1, I feel that the current use of the term, allelopathy, should include any direct or indirect harmful effect by one plant (including microorganisms) on another through the production of chemical compounds that escape into the environment. 1982 J. B. HARBORNE Introd. Ecol. Biochem. (ed. 2) viii. 212 In this case of allelopathy, as in most others, the toxin is effective against many but by no means all competing plant species. 1988 New Scientist 7 July 54/1 The rhododendron also poisons the soil with short-chain aliphatic acids, deterring plant roots of other species—a phenomenon known as allelopathy. Hence allelopathic a., pertaining to or of the nature of allelopathy; esp. designating a plant product having such toxic or inhibitory qualities. —Oxford English Dictionary

“Allelopathy is a process by which a plant releases chemicals that can either inhibit or benefit other plants. Since most allelopathic plants cause harm to other plants, that’s the what I’ll be discussing here. Species competition ensures the biodiversity of ecosystems. All plants and animals have developed techniques for out-competing other species for nutrients, water, territory, and other resources. For example, certain plants have extremely dense root systems. Allelopaths are plants that have an advanced weapon in their arsenal. The allelopathic plant competes with other species through ‘chemical warfare’ by releasing chemicals that inhibit the growth of its competitors. Allelopathic substances work like herbicides, preventing the germination and growth of the seedlings of competing species. Plants that are under stress, such as those with pests, diseases, or less than optimum access to nutrients, sun, or moisture, are at an even higher risk for being eliminated by allelopaths. Depending on the plant, allelopathic substances can be released from a plant’s flowers, leaves, leaf debris and leaf mulch, stems, bark, roots, or soil surrounding the roots. Some of the chemicals biodegrade over time while others can be persistent in the soil. Probably the most well-known allelopathic plant is the black walnut (Juglans nigra) tree. All parts of the tree–roots, bark, leaves, nuts, and even rainwater that falls off a leaf–release an allelopathic substance called juglone. Some species are affected by it and others aren’t bothered at all. Other common trees with allelopathic properties include eucalyptus, sugar maple, tree-of-heaven, hackberry, southern waxmyrtle, American sycamore, cottonwood, black cherry, red oak, black locust, sassafrass, and American elm.”

—from a blog called Earth Friendly Gardening

N.B.: Many of the fall colors we admire are actually produced by such allelopathogens as these. When we go out to see the colors we are, as the Earth Friendly blogger suggests, also seeing a kind of “chemical warfare.”

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