Each flowering branch of viper's bugloss grows longer as the season progresses. They are curled at the ends, revealing buds that successively open as the unfurl. Late in the season they have achieved this look. Viper's flowers once in its lifetime. Unlike century plants, that normally takes only two years, but can be a year or two longer. The flowers last two days. The male parts produce pollen on the first day, the female parts become receptive on the second. Most of the nectar is produced on the first day. After that the flowers begin to husband their resources for seed production.