foliage

Foliage is the collective leaves of plants, including needles and fronds, as distinct from stems, flowers, and fruit. The term also describes the leafy vegetation of a particular place or biome. In botanical contexts, foliage is categorized by leaf arrangement, shape, and lifespan, such as evergreen versus deciduous flora.

Leaves carry out photosynthesis, transpiration, and gas exchange through stomata. They vary widely in size, form, and texture, from simple broad leaves to compound structures with multiple leaflets. Morphological features such as margins, venation, and leaflets influence light capture and water use. Leaves may be evergreen, retaining foliage year-round, or deciduous, shedding seasonally.

Foliage contributes to habitat and microclimates by providing cover, modifying temperature and humidity, and supporting herbivores and pollinators. Seasonal changes in foliage color and density impact ecological interactions and aesthetics in landscapes and natural areas.

In horticulture and landscape design, foliage is a primary consideration for color, texture, and structure. Practitioners select species with appropriate foliage to achieve seasonal interest, year-round cover, or specific pruning outcomes. Management includes watering, nutrient supply, pest and disease control, and pruning to maintain shape and health.

In forestry, foliage is used to assess canopy density and leaf area index, important for estimating photosynthetic capacity and carbon balance. Foliage health can reveal stress from drought, disease, or pests.

See also related terms include leaf area index, evergreen, deciduous, and arboriculture.