The crepe myrtle was lavender a few days ago.

 Yesterday, it was quite white.  I thought it was because I had put all those cypress branches under, or the recent rain changed the pH, or diluted the minerals.    But the other cypress without any cypress branches also had whitish flowers.  An evening walk around showed that most of these Basham Party Pink crepe myrtles also had whitish flowers.   It was a sunny late afternoon.

 Today the flower clusters had a decidedly more lavender color.

 Closer examination showed that the flowers now had two colors in the same cluster, nearly white, and distinctly lavender.  Maybe the sun helped newly opening buds create a stronger color.

Online somebody said that they had a crepe myrtle which was one color on one side, and another color on the other side.

I have never seen this before.  Most likely it only happens when lavender producing conditions are marginal.