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?
Selleck, G.W.; Coupland, R.T.; Frankton, C.(1962). Leafy spurge in Saskatchewan. Ecological Monographs. 32:1-29. free .pdf.