underbark

Underbark is a term used in botany and forestry to describe the layer of tissue situated directly beneath the outer bark of woody plants. The composition of this zone varies by species, but it generally includes the inner bark (phloem) and, inward, the vascular cambium, the thin meristem responsible for growth.

The underbark region plays a key role in nutrient transport, moving sugars from leaves toward roots and developing tissues. It also participates in wound response and storage in some species. The exact arrangement of phloem, cambium, and other tissues varies among species, but underbark commonly refers to this interior layer just beneath the outer protective bark.

In practical terms, underbark is relevant for forestry management and wood processing. Debarking removes the outer bark to access the underbark tissues, which can influence moisture, pest habitat, and disease risk. Insects such as bark beetles often target the underbark zone, and understanding its condition helps in pest control and wood sanitation. The term remains informal and context-dependent rather than a strict anatomical designation.