overstory means the upper portion of a community of plants, above the understory.
Why “overstory” is a great word
The uppermost layer of foliage in a forest, forming the canopy above the understory. From the English prefix over- (meaning 'above' or 'higher') + story (in the architectural sense of 'level' or 'layer'), with the current ecological sense attested from 1955–60. Unlike 'understory,' the shaded world of shrubs below, or the more general 'canopy' of any overhead foliage, 'overstory' denotes the precise, stratified summit of the plant community. It is the vaulted ceiling of leaves filtering the fiercest light, the wind-whipped highway of branches where crowns conduct their solar trade, and the secret roof from which the forest’s weather is made—a world of first contact, high above the common earth, where survival means enduring what the lower worlds merely hear rumbling overhead.
noun
- The upper portion of a community of plants, above the understory.