Sandmat and Ants: Pollination?

It is spring and the flowers are blooming in Arizona.

Do you recognize the plants? I believe they are smallseed sandmat, Chamaesyce polycarpa.

In any case, ants were all over them.

On the day I visited, Dorymyrmrex bicolor workers were everywhere. Getting a little closer...

I could see the front of the ant's head was covered with pollen.

Two more workers, with equally yellow mandibles.

The Dorymyrmex workers were definitely visiting the flowers* (see below).

I also saw Pogonomyrmex californicus workers in the sandmat.

They weren't visiting the "flowers," though.

The Pogonomyrmex workers were searching under the plants. I saw a lot of gasters in the air. Perhaps they were searching for seeds? I also wondered if there were extrafloral nectaries under the leaves or on the stems that were attracting the ants.

Frankly, I wasn't that familiar with these little plants, so I wasn't sure where the nectaries were.

Upon investigation, it turns out that what look like *flowers* are actually special flowering structures unique to euphorbs called cyathia (singular cyathium). What look like anthers are actually male flowers and at the center is a female flower. The dark reddish areas near the center are the nectar glands within the cyathia. (For more details about the flowering structures see Wayne's Word (scroll to absolute bottom of post) or the flower structure of euphorbs.)

In any case, it seems like this plant would be a great one to add to an ant garden. I'm looking forward to learning more about it's life cycle and how ants interact with it.

What do you think?

One thought on “Sandmat and Ants: Pollination?

  1. James C. Trager

    We have some related plants around here, Euphorbia (Chamaesyce?) repens, etc., that grow in places like well-compacted gravel parking lots and sidewalk cracks. These are eagerly visited by a variety of ants, and almost never by any sort of bee or other typical pollinator, so I've always assumed they are ant-pollinated. It's hard to get these low plants to survive the competition from taller plants in plusher conditions, though, so not an easy one to put in the ant garden, except maybe could be gotten to colonize gravel paths or a pile of coarse sand.

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