Hydrangea macrophylla ‘Merveille Sanguine’
(syn. ‘H. macrophylla ‘Brunette’)
Or literally ‘Bloody Marvellous’ and rightly so! The dark green shiny leaves gradually turn mahogany in autumn with deep dark red mop-heads (purple in acid soils). Slower growing to about 1m+ if happy. Colours better in rich soil in sun.