binnenbast

Binnenbast is the inner bark of a woody plant, the phloem tissue located inside the outer bark and outside the wood. It forms part of the bark system and is involved in the transport of sugars and other metabolites from the leaves to other parts of the plant. The cambium lies adjacent to the inner bark, and as the tree grows, the cambium produces new phloem toward the outside and new xylem toward the inside.

Anatomy and composition: Binnenbast mainly consists of phloem tissue, including sieve elements, companion cells, and phloem parenchyma. In many species, bast fibers within the inner bark contribute tensile strength. The exact cellular composition and the amount of fibrous material vary with species, age, and environmental conditions.

Functions: The primary role of binnenbast is the transport of photosynthates (such as sugars) from sources (like mature leaves) to sinks (growing tissues, storage organs). It also participates in nutrient storage and, to some extent, in defense responses. Damage to the inner bark can disrupt sap flow and impair the tree’s growth or health.

Uses and cultural aspects: The term bast refers to fibers obtained from the phloem of stems, and in various plants these fibers have been used for rope, twine, and textiles. Harvesting binnenbast for fibers or other uses must be done carefully, as excessive removal can harm the tree and reduce vigor or kill it.

See also: Bark, Phloem, Bast fibre, Dendrology.