By Amy Weiss

Sep 26 2019

Ants might not be the first animal you think of dispersing fruits and seeds, but this is an important pathway many plants use. Seeds dispersed by ants have a lipid-rich attachment called the elaiosome. Ants are attracted to the elaiosome and carry these seeds into their colonies. There, they feed the elaiosome to their larvae, and discard the otherwise intact seed in an underground waste chamber or outside the nest. The ants get a tasty snack, and the seed gets a ride away from the competition of their parent plant—ending up in an ant compost heap full of nutrients.

Acacia is the largest plant genus in Australia and, as a result, is probably the most frequently ant-dispersed group of plants on the Australian continent.¹ While many ant species may interact with seeds, only a small subset act as effective dispersers. In Australia, the stars of seed dispersal are members of the ant genus, Rhytidoponera (pictured on postcard).¹

Here in North America, the majority of ant-dispersed plants are spring ephemerals—wildflowers that grow and flower before the trees leaf out, blocking the sunlight. There is less food available to ants in the spring, making these seeds with their attached elaiosome very appealing.² Some of the spring ephemeral species that rely on ants include Trilium, Viola (violets), Dicentra cucullaria (Dutchman’s breeches), Sanguinaria canadensis (bloodroot), and Erythronium americanum (trout lily).²