How does the yellow prairie violet use ants?
By Chelsie Vandaveer
July 16, 2003
The yellow prairie violet (Viola nuttallii Pursh) is a cool temperate plant. Native to western Canada and the U.S., it ranges as far south as New Mexico. But in the warmer regions, it is found growing only in upper elevations. The violet depends on ants like the black sub-alpine ant (Formica podzolica Francoeur).
The yellow prairie violet is myrmecophilous or "ant-loving", offering ants a treat they cannot resist. Attached to the seed is an elaiosome, a specialized fleshy organ rich in proteins and sugars. It is tailor-made to ants' tastes in food. Dropped from parent plant, the violet seeds immediately attract foraging ants which carry them back to the nest. The elaiosome is removed from the seed and eaten by the colony. After stripping away the elaiosome, the ants discard the seed unharmed.
Ants remove debris from their nests--feces, uneaten foods, dead ants--and place the items in refuse piles. The yellow prairie violet's seed is cast among the debris. The colony's trash heaps are nutrient-rich compost piles for violets.
Myrmecochory or "ant dispersal" appears a frequent trait for plants with tiny seeds. The ants benefited from a special treat, but the violet benefits more. A seed in the ants' possession is kept away from insects that could destroy it. Carried far from the parent plant, the violet will grow without having to compete with its parent for water and nutrients. And it ends up 'planted' in a higher quality soil than if left to wind dispersal. (The Ants, Bert Hölldobler and Edward O. Wilson, Belknap Press of Harvard University Press, Cambridge, Massachusetts, 1990)
Rocky Mountain Rare Plants has a beautiful photograph of Viola nuttallii taken by Bob Skowron. To view the photograph, click on the link:
Click here to view the photograph
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