By Jessica Fleming

Medicinal plants encompass a wide variety of cultivated and wild species that grow in diverse habitats and soil types. While nearly all medicinal plants are miraculous in their own ways, very few can contend with the transient magnificence of spring ephemerals, the wildflowers that blossom at the fringe of winter and spring. Through snow and sleeting rain, ephemerals bloom from February to April and are specifically adapted to maximize filtered light through a leafless canopy. Because they bloom at the winter-spring transition, the weather is too cold for most pollinators to fly. Thus, ephemerals rely heavily on ants for seed dispersal in a relationship that is not only symbiotic, but also symphonic in its closeness to perfection. As the theme for this year’s Journal of Medicinal Plant Conservation is “At Risk Plants in Trade,” a tribute to “myrmecochory,” the synergy between ant and plant, may supplement our ecological appreciation for the insects that ensure survival of our beloved spring ephemeral plant species in trade.

Numerous endangered, threatened, and cultivated medicinal species are considered spring ephemerals. Sanguinaria canadensis (bloodroot), Erythronium americanum (yellow trout lily), Arisaema triphyllum (Jack-in-the-pulpit), Claytonia virginica (Virginia spring beauty), Allium tricoccum (wild ramps), and Trillium spp. (trillium) are only a few of the estimated 11,000 species that are heavily reliant or secondarily reliant on myrmecochory for seed propagation.^[1]

Ephemerals, true to their name, bloom for only a short period of time. They must create a seed that is irresistible to ants. At the heart of myrmecochory and seed propagation is the elaiosome. Elaiosomes are lipid-rich seed appendages, akin to ornamental hats, that differ in fatty acid, starch, volatile oil, and nutrient chemistries, depending on which ant species utilize them.^[1] What is it about elaiosomes that attract ants to participate in this beautiful duet? Elaiosome nutrients are key to ants raising healthy young (larvae).

While much of elaiosome chemistry remains to be discovered, research has shown elaiosomes lure ants with irresistible scents. Volatile oils cue ants to seed-carry, attuning them to their abundance of nutrients. ^[1] Ants gather the seed-elaiosomes in their mandibles, a haul that can be up to 5,000 times their body weight. ^[2] They can travel up 180 meters to feed the nutrient-rich elaiosomes to their larvae, but most often, seeds are dispersed anywhere from 0-1.5 meters from the plant itself. Research has also shown that seeds may not germinate unless the elaiosome is removed, a job performed specifically by ants within the nest.^[1] Ants then discard the seed in one of their nitrogen-rich tunnels, a warm luxurious place for a seed to sprout.

Thus, as one marvels at the winter forest’s flowers, ants are often the ones to thank. Plants are stationary organisms after all, and mastering seed dispersal across a vast forest floor takes millions of years of perfection. Flying pollinators get their buzz with hives and groups committed to their salvation. But the unsung invisible heroes of our forests are in fact doing the gardening underground [science.org don’t crush that ant, August 2020]. Ants are the eloquent composers of one of our most intriguing and beloved sights in nature— spring ephemerals. Thus, on your next medicinal plant adventure, look under the leaves and tread lightly. A busy world of ant tunnels bustle below the surface, planting our favorite medicinal ephemerals in a symphony that blooms as the result of an ant’s composition.

References

1. Sasidharan, R., & Venkatesan, R. (2019, June 28). Seed elaiosome mediates dispersal by ants and impacts germination in Ricinus communis. Frontiers in Ecology and Evolution. Retrieved February 27, 2022, from https://www.frontiersin.org/articles/10.3389/fevo.2019.00246/full 
2. Ants Can Lift up to 5,000 Times Their own Body Weight. (2017, December 24). Entomology Today. Retrieved February 27, 2022, from https://entomologytoday.org/2014/02/11/ants-can-lift-up-to-5000-times-their-own-body-weight-new-study-suggests/
3. Pennisi, E. (2020, August 11). Don’t crush that ant—it could plant a wildflower: New findings show how ants choose and protect the seeds they disperse. Science. Retrieved February 27, 2022, from https://www.science.org/content/article/don-t-crush-ant-it-could-plant-wildflower

Jessica Arconti Fleming is president of the Blue Ridge Wildflower Society, a conservation organization dedicated to teaching the public about native plants and habitat restoration. Jessica is also a third year internal medicine resident physician at Virginia Tech Carilion in Roanoke, VA.