Ascent of Sap

Water and the mineral ions dissolved in it, once they have reached the xylem, are together called sap, and the process of carrying that sap upward through the plant - against gravity, and in the case of the tallest trees to well over a hundred metres - is called the ascent of sap. The scale of this task is enormous: millions of individual root hairs each contribute only a tiny trickle of water, but these trickles combine within the xylem, which acts as a superhighway able to move a very large combined volume of water upward, …