Fully hardy, rounded, deciduous shrub with broadly ovate, coarsely toothed leaves, to 20cm long, and almost spherical corymbs, to 20cm across, of large blue or pink, sterile flowers.  To 2m or more under suitable conditions.  Decorative garden Hydrangeas are mainly varieties of the Japanese H. macrophylla, pink to blue, all sterile.  H macrophylla cultivars are divided into two groups, Hortensias and Lacecaps.[RHSE, Hilliers’].