Evergreen means a plant retaining its foliage year-round (a botanist would say the leaves are persistent or notdeciduous). Most tropical plants are naturally "evergreen" in this sense, the main exceptions being species growing in arid climates or climates with an extreme dry season. In temperate climate zones, however, few plants are evergreen; most are deciduous. The majority of plants native to the wet tropics are evergreen, replacing their leaves gradually throughout the year as the leaves age and fall.
The other meaning of evergreen is that in reference to a conifer. Technically, this is incorrect since some conifers, the larch and Bald cypress for examples, are decidious and lose their needles once a year. But in temperate climates where the majority of trees that are angiosperms lose their leaves in the late Fall, the conifers stand out by retaining theirs throughout the Winter.
