BOTANY
'(<a href="http://www.j-archive.com/media/2007-05-16_J_25.jpg" target="_blank">Cheryl of the Clue Crew indicates a flower.</a>) The color of a hydrangea's flowers can be determined by the level of this in the soil; above 6 for <a href="http://www.j-archive.com/media/2007-05-16_J_25a.jpg" target="_blank">pink flowers</a>, lower for blue'
acid