“The word allelopathy derives from two separate words. They are allelon which means “of each other”, and pathos which means “to suffer”. Allelopathy refers to the chemical inhibition of one species by another. The “inhibitory” chemical is released into the environment where it affects the development and growth of neighboring plants.
Allelopathic chemicals can be present in any part of the plant. They can be found in leaves, flowers, roots, fruits, or stems. They can also be found in the surrounding soil. Target species are affected by these toxins in many different ways. The toxic chemicals may inhibit shoot/root growth, they may inhibit nutrient uptake, or they may attack a naturally occurring symbiotic relationship thereby destroying the plant’s usable source of a nutrient.
… Allelopathy is a form of chemical competition. The allelopathic plant is competing through “interference” chemicals. Competition, by definition, takes one of two forms–exploitation or interference.
Competition is used by both plants and animals to assure a place in nature. Plants will compete for sunlight, water and nutrients and, like animals, for territory. Competition, like parasitism, disease, and predation, influences distribution and amount of organisms in an ecosystem. The interactions of ecosystems define an environment.
When organisms compete with one another, they create the potential for resource limitations and possible extinctions. Allelopathic plants prevent other plants from using the available resources and thus influence the evolution and distribution of other species. One might say that allelopathic plants control the environments in which they live.” Cornell University
Table 1. Some allelopathic plants, the chemicals they produce, and the plants they affect.
|Allelopathic Species||Type of Chemical||Affected Species|
|Sugar Maple||Phenolics||Yellow Birch, White Spruce|
|Eucalyptus||Phenolics||Shrubs, herbs, grasses|
|Black Walnut||Juglone (Quinone)||Pines (Austrian, Scots, red, white), Apple, Birch, Black Alder, Hackberry, Basswood, Azalea, et al.|
|Sycamore (Planetree)||Coumarins||Yellow Birch, herbs, grasses|
|Black Cherry||Cyanogenic glycosides||Red Maple, Red Pine|
|Sassafras||Terpenoids||Elm, Silver Maple, Boxelder|
|Balsam Poplar||Green Alder|
|Southern Red Oak||Sweetgum|
|Laurel — Kalmia angustifolia||Phenolics||Black Spruce|
|Sumac||Phenolics, terpenoids||Douglas fir|
|Forsythia intermedia||Kentucky Bluegrass|
|Goldenrod, Aster||Phenolics, terpenoids||Sugar Maple, Bl. Cherry, Tulip Poplar, Red Pine|
|New York Fern||Phenolics||Black Cherry|
|Bracken Fern||Phenolics||Douglas fir|
|Shorthusk Grass||Phenolics||Black Cherry|
|Reindeer Lichen||Phenolics||Jack Pine, White Spruce|
|Tall Fescue||Phenolics||Sweetgum, Black Walnut, White Ash|
|Red Fescue, Kentucky Bluegrass||Azalea, Barberry, Forsythia, Flowering Dogwood, Yew|
|Colonial Bentgrass||Azalea, Barberry, Yew, Forsythia|
|Perennial Rye||Apple, Forsythia, Flowering Dogwood|
|Foxtail, Smooth Brome||Populus spp.|
List from Sustainable Urban Landscape Information Series (SULIS)