Devil's bit scabious - in white

Devil's bit scabious - in white

Observation - Devil's bit scabious - in white. Description: Devil's bit scabious is usually purple, but this is white. One of a few white flower heads on a single plant, among many devil's bit scabious plants that had the normal colour. Any idea of how frequent this anomaly occurs?

Devil's bit scabious is usually purple, but this is white. One of a few white flower heads on a single plant, among many devil's bit scabious plants that had the normal colour. Any idea of how frequent this anomaly occurs?