Ants In My Plants

It’s not enough to be busy, so are the ants. The question is, what are we busy about?

~Henry David Thoreau

I think we all fall into that trap sometimes, perhaps too often – just being busy for the sake of being busy. It was probably more true for me when given some seemingly meaningless paperwork task during my work years rather than now in my retirement (and, thankfully, that did not happen all that often in my career). And it is true that ants are busy creatures, all too busy for us if they manage to find ways into our houses. I do know one thing that ants are very busy about this time of year – and that is plants. Certain species of tropical leaf cutter ants are well known for their leaf collecting and fungus farming. It turns out our local ants do a lot of interesting things as well. They can serve as pollinators for some species of plants and nectar thieves for others. In fact, many plants have evolved clever ways to hinder access to their flowers by ground-dwelling insects like ants, presumably because these crawlers often raid the nectar without performing the efficient pollination of aerial insects. Hairy stems and sticky solutions from glands are but two of the mechanisms used to deter these raiders. But, in our spring woodlands, ants play another, often overlooked function. But you have to look closely to learn more…

Bloodroot seed pod backlit

Bloodroot seed pod as it starts to form (click photos to enlarge)

Yesterday, I shared some images of the Bloodroot flowers blooming in the yard. The petals on many of the plants are now gone, barely visible in the leaf litter. The stalk that once held the brilliant white flower is now topped with a slender green capsule.

Bloodroot seed pod mature

Mature Bloodroot seed pod showing how it splits to release seeds

To tell the rest of the Bloodroot story, I’ll need to borrow some images from the archives. These Boodroot seed photos were taken on a trip to the Smokies a couple of years ago in early May, a time equivalent to perhaps mid-April in these parts. I stopped to photograph some wildflowers and noticed the distinctive leaves and seed pods of a clump of Bloodroot. I could see one of the pods had split open and there were only a couple of seeds visible inside the pod, so I looked on the ground below.

Bloodroot seed on ground

Bloodroot seed on the ground beneath an open pod

Bloodroot seeds fall to the ground beneath the parent plant, a situation that is usually not ideal for a plant, due to potential limits of space, sunlight, nutrients, etc. This is why plants have evolved so many interesting means of seed dispersal using wind, water, and animals to help move their seeds to more favorable areas for successful germination. In the case of Bloodroot, and many of our other spring woodland flowers, that seed dispersal mechanism is directly related to ants. And the ants are not doing it out of the goodness of their tiny hearts, but rather for a self-serving reason related to that great motivator, food. You may notice the Bloodroot seed looks a bit odd, not much like the seeds you buy to plant in your yard. This seed looks like it has a polka-dot slug riding on it, or perhaps it has a plant version of a punk hairdo. What it really has is a lipid-rich appendage called an elaiosome (Greek élaion “oil” and sóma “body”).

Ant carrying Bloodroot seed

Ant picking up a Bloodroot seed

These lipid and protein-rich bodies are very attractive to ants and a variety of species of ants somehow manage to find these seeds soon after they fall to the ground. After reading about this phenomenon, I had tried to photograph it in my yard in Raleigh, where I had Trout Lilies planted in a natural area. I collected some seeds and laid them out on a piece of paper, hoping to see some ants come and collect them. I went inside to get my camera, and stayed in for a little too long it seems, because when I returned a short while later, all the seeds were gone. On this day in the mountains, I started looking around the plants and found several ants crawling about. I waited only a few minutes before an ant found one of the seeds ( I had brushed aside some leaf litter to make it easier to photograph the scene).

Ant carrying Bloodroot seed 1

Ant carrying Bloodroot seed

The ant quickly picked up the seed and struggled to carry it off, presumably to its nest. Ants eat the elaiosome (some say they also feed it to their larvae), and discard the seed. The seed has thus been transported away from the parent plant at least some distance, and often deposited underground in an ant nest trash pile, usually a great spot for germination and protection from potential seed predators like Deer Mice. One research paper I saw stated that the elaiosome itself may also provide some chemical deterrent to certain mammalian seed predators. This fascinating process of seed dispersal by ants has an equally fascinating name – myrmecochory. Some researchers say as many as 40% of the herbaceous species in some temperate woodlands like we have here in North Carolina rely on ants for their seed dispersal.

Bloodroot seed pod in early stage of development

Bloodroot seed pod in early stage of development

So, when you are in the woods these next few weeks, take a moment to ponder the miracles happening beneath your feet, and take a closer look to see if you, too, have ants in your plants. I know I’ll be looking, camera in hand.