Shoots grow above the soil

While roots grow under the soil, shoots are the part of plants that grow above the soil.  Roots and shoots are often thought of a different entities.  Actually, they are well-coordinated, separate but equal partners.  Buried to waist, so to speak, the lower body specializes in gathering raw materials, water and salts, and sending them up the line to the upper body growing above the ground.  Each half shares resources on a equal basis. 

The shoot, also called the stem, is not unlike a slim but sturdy multi-storied building.  Outside walls support the structure while an inside core supplies vital services to the upper reaches of the building.  In a skyscraper, the service core in the center houses elevators, electric systems, waste disposal and water supply.  In a plant, the service core is closer to the outside walls and is comprised of tubes that transport water, raw materials and food.  Instead of electric powered elevators, a plant used hydraulics to deliver nutrients to its cells and carry waste away. 

In other words, the plant’s delivery and disposal systems are based on water.  Roots constantly pull water molecules from the soil and send them up the stem, where they are then pulled into the leaf cover.  In a month’s worth of moisture-gathering, tomato roots draw ten gallons of water from the soil, pass it up the stem and into the leaves.  Leaves are the end of the water line. There, through tiny pores, the plant expels excess water into the air. 

The tomato plant actually uses very little of its gathered water for its own growing purposes.  Ninety-five percent (or 9.5 gallons) of the water absorbed by its roots is simply used to drive the delivery system.  Only 1/2 gallon is actually used directly by cells as hydration.  In one sense, a plant’s hydraulic system appears to be extremely wasteful.  However, my entire farm benefits from this apparent lack of economy.

Have you ever sat in the shade of a maple tree sipping a refreshing glass of lemonade on a hot summer day?  This pleasant environment is not only created by the shade of the tree.  The spot is also air-conditioned by the tree.  A tree acts just like a swamp cooler. (Or more accurately, a swamp cooler acts just like a tree.) As water evaporates from maple leaves, the air around the tree becomes cooler.  A maple tree throws off a prodigious amount of moisture.  Its leaves release 60 gallons of water per hour on a summer day.