Holly berries. The holly genus (Ilex) consists of more than 400 species, most of which are evergreen shrubs growing up to 15 metres, found in woodland throughout the world. The bright red berries develop from the female flowers, which are found on separate plants to those of the male of the species (dioecious). Holly leaves are spiny and waxy. It is cultivated for hedging and is used during the Christmas season as a decoration.