The Maypole - just what is it?

 I realized that if I wanted to test Mannhardt’s theory that the Christmas tree started out as a maypole that I would first have to figure out just what it was.  I had seen pictures of young women dancing around a flowered pole, holding ribbons that were slowly wrapped around it as the dance proceeded by I had no idea why they were doing that or what it meant.  Wikipedia was of little help on the matter.  It offered theories that the maypole was an expression of happiness that summer had arrived, that it was a tradition that had been started by Iron Age heathens or that it was a (gasp) giant phallic symbol.  Unfortunately, Wikipedia offered little in the way of evidence for any of this so I started trying to figure out just what it was myself.

The first thing I looked at was the name.  I had always assumed that the maypole was called that because it was put up in the month of May.  This turned out to be wrong, although there was a connection between it and May.  Both got their name from the same source: the Greek goddess Maia and was associated with fertility.  The name “maypole” was coined sometime in the 13th century.  This, as it turns out, is well after Northern Europe had been converted to Christianity.  This raised the possibility that the maypole was not, as Mannhardt had indicated, a heathen tradition but one that had been adopted by Christians.  In fact, according to Mannhardt’s research, some maypoles were put up on Christian holidays.  This exposed a serious flaw with his research - Mannhardt believed he was looking at heathen practices that had survived conversion, but the maypole appeared to be a Christian practice that had been developed in the later medieval period when Christianity was widely practiced.  Was it possible he was wrong?