With pale pink sterile florets. At www.rogerstreesandshrubs.com; they say: Hydrangea aspera ‘Rosthornii’ A large-leaved form of H. aspera. The true H. rosthornii, now considered part of H. aspera subsp. robusta, has leaf-stalks which may be up to 20 cm long.
Gardens found in the 28 pre 2000 surveyed: No gardens found.
UKPlant Finder 2012: Not Listed.