Holly (ilex) is a diverse genus of trees and shrubs, with more than 400 species that occur in temperate, subtropical and tropical regions across the globe.This popular landscape plant is best known for the …Small, axillary, greenish-white flowers bloom from april to june.Like most others in the holly genus, american holly is dioecious.Pistillate flowers emerge in small clusters from one plant, while staminate …Along the west coast of north america, from california to british columbia, english holly (ilex aquifolium), which is grown commercially, is quickly spreading into native forest habitat, where it …