A fruit-like structure that has developed from the ‘free’ carpels of a single flower and is composed of a number of separate fruits.
The flower may have 50-100 carpels but the number of druplets produced will depend on the number fertilised which in turn may depend on the weather and the number of visits by pollinators. In commercial studies ‘druplet set’ ranged from 40% to 80%. Druplet set can also be affected by viruses or fungal growth. Some species can self-pollinate if no pollinators are present.
The Blackberry is the fruit of the Rubus genus. It is an ‘Aggregate’ fruit because it is made up of a number of drupelets (small drupes). The first photo shows a single blackberry. Each blackberry is made up of a number of druplets formed from the individual carpels at the centre of a single flower.
This photo shows the fruit of a Clematis vitalba Travellers Rest. The fruit is an aggregate of achenes.
This photo shows the fruit of a Delphinium which is an aggregate of follicles.