R. officinalis (Rosemarie) is a bushy shrub with a dense, leafy habit, to 2m x 2m but variable in size. Linear dark green leaves 1.5-5cm long have recurved margins and pale, felty undersides.
Flowers usually pale violet-blue and white. Flowering starts in spring but is often repeated at differing times of year.
Both habit and flower colour can be variable, from prostrate to upright, from deep blue to paler and white tones, pink or purple.