Lehtoputki

Lehtoputki is a term from Finnish botanical terminology used to describe the leaf’s vascular tissue—the network that transports water, minerals, and organic nutrients through the leaf. The name translates roughly to "leaf tube." In most leaves the lehtoputki consists of vascular bundles aligned along the leaf axis, typically forming a central midrib with branching veins. In dicot leaves the venation is reticulate, while monocots often show parallel venation. Each vascular bundle contains xylem toward the upper side and phloem toward the lower side, sometimes with surrounding supportive tissue.

The primary functions are to conduct water and minerals from the stem via the xylem and to distribute sugars and other metabolites produced during photosynthesis via the phloem. The lehtoputki also contributes to mechanical support and may participate in signaling within the leaf. Developmentally, these vascular conduits arise from the leaf primordium’s procambial strand and become elaborated as the leaf grows; vein density and arrangement vary among species and influence leaf morphology and physiology.

Variation in the lehtoputki affects photosynthetic efficiency, drought tolerance, and leaf stiffness. In Finnish botanical literature the term is commonly used to refer to leaf venation and vascular bundles, and it is sometimes discussed alongside general concepts of leaf anatomy and plant transport systems.