Have you noticed the western bleeding hearts and wild ginger in bloom this past month?
As the flowers fade and the seeds develop, you may notice ants marching to and fro around these plants. Both bleeding hearts and wild ginger have developed a symbiotic relationship with ants. The seeds of these plants have a fatty protein-rich tissue called an elaiosome attached to them. Ants carry these seed to their nests, eat the elaiosome, and then ditch the intact seed in their trash pile. The elaiosome is not needed for the seeds to germinate. Seeds then sprout in a nutrient rich area away from the original colony of plants. This form of seed dispersal facilitated by ants is called myrmecochory.
There are at least 11,000 species plants that have elaiosomes on their seeds. There is no single common ancestor for elaiosome development. Plants have evolved this adaptation in different ways multiple times throughout history. Elaiosomes are a great example of convergent evolution – the independent evolution of similar structures that serve a similar purpose. Some other plants that have evolved elaiosomes include trilliums, celandine, violets and many more!