In botany, an evergreen plant is a plant that has leaves in all four seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season. There are many different kinds of evergreen plants, both trees and shrubs. Evergreens include:
The Latin binomial term sempervirens (literally, "always green") refers to the evergreen nature of the plant, for instance:
An additional special case exists in Welwitschia, an African gymnosperm plant that produces only two leaves which grow continuously throughout the plant's life but gradually wear away at the apex. Welwitschia can live for over 1,000 years.
Leaf persistence in evergreen plants varies from a few months (with new leaves constantly being grown as old ones are shed) to several decades (over thirty years in the Great Basin Bristlecone Pine).
They are small evergreen shrubs growing 10–60 cm (4–24 in) tall. The leaves are simple and minute in some species, or pinnate, finely divided in other species, often densely silvery hairy, and usually aromatic. The composite flowerheads are yellow or white, produced in dense globose capitulae 1–2 cm in diameter, on top of slender stems held 10–25 cm (4–10 in) above the foliage. There are no ray florets.
Santolina species are used as food plants by the larvae of some Lepidoptera species including Bucculatrix santolinella (feeds exclusively on S. chamaecyparissus) and the Coleophora case-bearers C. albicella (recorded on S. chamaecyparissus), C. involucrella (feeds exclusively on Santolina spp) and C. santolinella (feeds exclusively on S. chamaecyparissus).