Overview:
By Karen Edgington
Each week, Signal Akron will help you in your gardening adventures with an excerpt from "The Root of It," a monthly newsletter from the Summit County Master Gardeners, Ohio State University Extension.
It is always satisfying to see two organisms living in a mutualistic relationship – one in which both parties benefit.
Certain ants and plants have such a relationship, and an elegant one. Close inspection of the seed of a bleeding heart (Dicentra spectabilis) reveals a fleshy structure called an elaiosome (e-LAY-o-zome) attached to the smooth, hard seed coat. The elaiosome is made of and secretes fatty cells and other nutrients. These delectable treats attract ants, which are crucial to seed dispersal and ensure the survival of this species.
Ants carry these tasty tidbits back to their nests, consume the exterior goody and then dispose of the seed in their ant “compost pile.” This ant-created seedbed contains well-aerated, fertile soil and is protected from marauding rodents and other scavengers. There, the seeds find the perfect growing site and conditions to germinate and grow on.
Many spring ephemerals rely on this seed dispersal strategy: trillium, bloodroot, Dutchman’s breeches, hepatica, squirrel corn. Violas, wild ginger, carex and a host of other plants have elaiosomes and a relationship with nearby ant colonies.
To date, scientists have found elaiosomes in over 11,000 plant species across 77 plant families. They have determined that certain seeds will only germinate once the elaiosome has been removed, perhaps a mechanism to break dormancy.
Yet, most seeds germinate more quickly with their elaiosomes intact. The elaiosomes on these seeds may act as a water reservoir to facilitate water absorption and seed hydration. Researchers are on the job, figuring out the how and why of this interesting plant structure. Scientists note that the anti-microbial properties present in ant nests offer these collected seeds protection from pathogens.
Seed dispersal by ants (known as myrmecochory) improves the odds of germination for many plant species, and ants are happy foragers when these nutrient-dense, elaiosome-bearing seeds are brought back to the communal nest. Look for the interactions of these plant and ant species, and witness the art of living together.
Look around!
