The plant now grown as ‘Sir Joseph Banks’ is very different from a dried herbarium specimen deposited at the time of introduction be Banks.  The current cultivar has very large flowers up to 25cm, white washed with pink or mauve. Sterile florets with four sepals that do not overlap. Although the fertile florets are hidden under the sterile florets, they are the largest of any Hydrangea.

Gardens found in 28 pre 2000 surveys WAK EBG KEW MS

Gardens found in the 10 surveyed in 2010: NAN AW

UK  Plant Finder 2012: Not listed.