Have you ever heard a gardener comment, “Spurge plants always have ants,” and wondered if it was true? I admit searching ground spurge (Chamaesyce prostrata) for ants when I find the weeds, and I am often rewarded. Ants are attracted to spurge seeds (previous post), but is there more to the story?
Let’s take a look at a spurge with numerous ants milling around it. Most are Forelius.
The ants seem to be visiting the complex structures that pass for flowers in ground spurge.
In this photograph the ant on the right appears to be visiting the flower. But there is also an aphid on the same plant.
Yes, there are aphids on the plant.
The ants are also collecting honeydew from the aphids.
This leads to the question, how significant are the two sources of sweets? Ants are known to regularly visit the nectaries of the invasive weed, leafy spurge, but I wasn’t able to find out much about ground spurge.
Another question arises about whether ants might be capable of pollinating ground spurge. Ants are thought to pollinate certain low-growing plants with small flowers that are tight to the stem, and ground spurge certainly fits the bill.
Selleck, et al. 1962 reported that leafy spurge was pollinated by ants. After reading their evidence, however, it might be a shaky conclusion.
What is up with ants and spurge? Do ants visit spurge where you live? Do the ants gather nectar? Any evidence of pollination?
Reference:
Selleck, G.W.; Coupland, R.T.; Frankton, C.(1962). Leafy spurge in Saskatchewan. Ecological Monographs. 32:1-29. free .pdf.
Good questions! I often see ants at these in gravel parking lots and along foot paths. Indeed, I once observed 7 different species of ants visting spurges in the gravel mulch of a largish tree planter box (10 X 10 ft) at a gas station, completely surrounded by pavement and plowed ag fields – an oasis in an ant desert, if you will.
Ants are attracted to spurge in my garden and on the gravel driveway. On the driveway they seem to collect and store all the tiny rock particles around the plant base and colonize. In the garden they seem to colonize around the plant base in the garden beds. I cannot comment on the reasons for doing so because I haven’t spent enough time observing their actiivty but I assume it may be the harvest of seeds since spurge is a prolific producer of seeds.
That is a good point. Do you have any ideas what kinds of ants are involved?
From observing the relationship of ants and spurge in lawn-soil:
One idea I have had is that the fast-growing root system of the spurge might be attractive for the ant’s nest-making proclivities.
Perhaps this and the other factors spell land of milk and honey for the ants.
Johnny,
Those are some things I hadn’t thought of. Interesting ideas.
I have noticed ants seem to be everywhere spurge is found.. In my garden, ants build their nests under spurge plants.
Jewel,
That’s a cool observation Do you know what kind of ants?
A list of ant species I have found on creeping spurge here in Missouri includes Forelius pruinosus, Crematogaster lineolata, Monomorium minimum, Pheidole pilifera, Formica pallidefulva, F. incerta, F. subsericea, Lasius neoniger, Nylanderia terricola.