Dichroa febrifuga 'Blue Cap'Dichroa febrifuga 'Blue Cap' Evergreen Hydrangea This plant is more correctly known as Hydrangea febrifuga 'Blue Cap', but we have retained the old genus Dichroa at this time to minimise confusion. Native from Nepal to China and Vietnam in the Himalayan foothills, growing in moist forests. This plant in the Hydrangea family is an evergreen shrub growing 2 3 m with white buds that open blue, lilac, or pink through summer, depending on soil pH. Height: