Hydrangea involucrata 'Involucrata'
This is a remontant shrub that grows slowly. It is very interesting because of its distinctive buds: they are spherical and are enclosed in six velvety bracts that fall off when the inflorescence opens, leaving residues on the branches. This hydrangea is much used for mixed borders, where the vivid blue of the fertile flowers and the white of the sterile ones create interesting chromatic effects.