Hydrangeaceae

Opposite, often toothed leaves on shrubs; flower clusters typically mix small fertile flowers at the centre with a showy ring of larger, sterile, petal-like flowers around the rim, the outer ring doing all the work of attracting pollinators from a distance.

The showy outer 'flowers' most people picture on a hydrangea are usually sterile, producing no seed at all — the real, fertile flowers are the small, unremarkable ones clustered at the centre.

To check whether a plant belongs to Hydrangeaceae, compare the leaf arrangement, leaf type, flower symmetry, fruit type, and one distinctive marker together. A single feature can mislead; the family pattern is the combination.