Hydrangea serratifolia

Closely related to H. seemannii, this species from Chile is also a self-clinging evergreen with leathery leaves, but has densely set, entirely fertile, creamy-white flowers in crowded, fairly spherical panicles, up to 15cm long in late summer. Will grow happily in sun or shade, but will flower best on a sunny wall. Still rare in the UK, this is the real thing, apparently most others are not.