Chapter 36.3, Problem 2CC

Summary Introduction

To explain: Why a drop of water collects at surface of rooted stump when cut at dawn, but not in noon.

Concept introduction: The supply of some solutes and water to the aerial system of the vascular plants is conducted by the xylem. There is a network of pipelines extending from roots to the leaves in xylem. Under some conditions like when xylem sap is more dilute than the soil solution water is transported rapidly into the xylem vessel. Solutes and water are essential ingredients of root pressure. The entry of other solutes and water into root cells including xylem tissue of these ingredients is essential for the development of the root pressure.