Verbena is a genus of plants in the Verbenaceae faemily. The genus contains approximately 250 different species. Some Verbena species are annuals, only lasting a single season, while others are perennial, come back year after year. Through out history many different cultures, such as the Egyptians and Romans, have viewed Verbana as a type of holy plant. Even ancient Christians used to refer to common vervain as Holy Herb.
Although common vervain is not native to North America it has been introduced there and it is now invasive. Other species of Verbana are native to North America. The two species above are Verbana that are native to the area that I live. The top photo is an example of blue vervain and the bottom is an example of hoary vervain. Although both were photographed at Purgatory Creek they prefer different types of habitat. Blue vervain prefers to live in areas with wet soil while hoary vervain usually is found where the soil is dry.