How the fuck would a plant know if it's surrounded by females? They don't have eyes... Telepathy maybe?
I used to have a link to a really interesting research study, which unfortunately I lost along with about a ZILLION other links and EVERYTHING I had when I had total computer failure last December, but plants can and will do amazing things.
Over several seasons a crop of plants on a cliff on the leeward side of some island where a wild crop was growing researchers removed all the male plants. Each year a very high percentage of the females on roughly the first third of the plants on the windward side of the group turned hermie. Roughly the middle third had slightly less than half turn hermie and the third on the leeward side had none that turned hermie.
Without the link to go back and double check exactly what the researchers formulated, basically they said that at some point when females are not pollinated there are various things than can trigger females to turn hermie. Some are stresses like indoor growers have problems with like light leaks or other types of stresses right down to a root-bound condition, but in the case of the island crops the researches determined that it was just the near constant, and at times high, wind striking the plants that were more on the windward side.
They came to that conclusion after one year setting up a wind block and the number of hermies dropped way down. They also figured that was evidence of why the plants on the far windward side hermied the most and in the middle there were less and on the leeward side there were none, that the plants themselves created a wind block for the plants farther to the leeward side.
So I would say that it is not a case of a group of all female plants not being pollinated somehow communicating and deciding that one or some or all will hermie but rather something in their genetic coding that once they reach a point during flower and are not pollinated something will 'kick into gear' and they will allow, or maybe even 'look for' certain stresses, even ones we might not consider stresses, or natural triggers to cause one or some or all to turn so they can then perform their one and only task, their singular reason for existing to occur, that being making seeds to perpetuate the species.