1. The Vascular System

2. Xylem
Xylem: transports water and dissolved minerals up from the roots to the rest of the plant. One way street
Called complex tissue do to having more than one type of cell:
Tracheid: specialized cells. Long and narow, and water flows in tracheids through openings in the thick cell wall
Vessel elements: shorter and wider than tracheids
Both cells die before water moves through them
Onces dead: the cell walls disintegrates, connect, and form long tubes end to end

4. Xylem
Plants spend no metabolic energy to move the water through the xylem
Cohesion-tension theory: physical properties of water allows the rise of water through the plant
Hydrogen bonds cause force called cohesion
Water molecules also attracted to the cell walls: adhesion
Capillary action: moves water up the sides of the slightly to form a miniscus
Transpiration: water lost from the plant leaves
Transpiration causes a vacuum and this moves water up the plant

7. Phloem
Phloem: Transports nutrients, minerals and sugar throughout the plant. Two way street
Moves product of photosynthesis from leaves to stems and roots.
Phloem tissue is alive unlike xylem cells which are dead
Complex tissue made up of several cell types
Sieve tube members: have small holes in the end walls which allow sap to flow through
Sieve tube members have no nucleus or ribosomes ( lost during formation
Companion cells: assist them and are connected to them by plasodesmata
which serves to keep them alive

10. Phloem
Xylem moves water in one direction but phloem flows in any direction depending on the plants’ needs
Pressure-flow model: theory that explains how food or sap moves through the plant
Flows from a sugar source to a sugar sink
Source: any place where sugar concentration is high (leaves, roots)
Sink: any part that is using or storing the sugar to use such as growing shoots, stems, fruit, or even storage roots (will become a source later in the season)
Sources and sinks change as the plant grows, needs change, and seasons change

11. Phloem
Many Plants use ATP to load sugar at a source which creates high concentration of sugar and low concentration of water… osmosis flow occurs which requires no energy
At the sink, plants also use ATP to unload the sugars
Osmosis pressure keeps the sap flowing from source to sink requiring no energy