Plants have evolved three basic organs - roots, stems and leaves - that are organized into root and shoot systems. Each organ contains dermal, vascular and ground tissues. Secondary growth in woody plants occurs due to the vascular cambium, producing secondary xylem and phloem. Water and minerals enter roots through cell walls and membranes by transmembrane, symplastic or apoplastic routes. They move upwards via root pressure, cohesion-adhesion-tension and transpiration. Transpiration is influenced by environmental factors and causes guttation. Photosynthates are translocated from source leaves to sinks through the phloem sieve tubes via sucrose molecules moving from high to low concentration.