Recent estimates suggest that plants contribute up to 80% of all biomass on earth. Despite the staggering diversity in plant shape, size, life cycle and habitat found across the different continents; dominant land plants share a highly important characteristic: the presence of a vascular system. This anatomical feature found in the majority of plants has been widely accepted to define plants containing tracheary tissues as vascular plants or tracheophytes.

Due to the presence of a cell wall, plant cells are fixed within their tissue context and cannot move relative to each other during development. Plants thus need to rely on directed cell elongation and cell division to generate a full three-dimensional (3D) structure. Intrinsic polarity cues and cellular communication provide spatial information to plant cells and establishes their position relative to the tissue context and the axis of growth.