Plant Anatomy

Unit 1Chapter 6Lesson 1

The Importance of Plants

• Without plants, life on earth could not exist• Plants are the primary source of food for

humans and animals

The Importance of Plants cont.

• Plants also:– Provide oxygen– Provide shade– Supply us with medicines– Renew the air– Slow down the wind– Hold soil in place– Are a home for wildlife– Furnish building materials and fuel

Parts of the Plant

• Most plants are made up of four basic parts:– Leaves– Stems– Roots– Flowers (these later

become fruit or seeds)

Roots

• Usually underground – not visible• Functions:– Anchor the plant and hold it upright*– Absorb water and minerals from the soil & conduct

them to the stem*– Store large quantities of plant food*– Propagate or reproduce in some plants

* = essential to all plants

Roots on the Inside

• Very similar to a stem• Older roots of shrubs &

trees have:– Phloem on the outside

(old phloem is bark)– Cambium layer– Xylem (wood) on the

inside

• Phloem– Carries manufactured food down to the root for food storage

• Xylem – Carries water and minerals up to the stem

Roots on the Outside• Different from a stem• On a stem, the terminal bud initiates growth• On a root, the root cap initiates growth• Root cap continuously

makes new cells that protect the root as it pushes into the soil

Root External Structure

• Behind the root cap are root hairs

• Root hairs become side roots that branch out as the root grows older

• Absorb moisture and minerals which are conducted up to the larger roots and the stem

Roots as Crops

• Cash crops– Carrots– Beets– Radishes– Sweet Potatoes

Root Propagation

• Plants with tuberous roots:– Dahlia– Peony– Sweet Potato

• Are propagated by separating the root clump or by rooting spouts from the root

Types of Root Systems

Fibrous Root System vs. Tap Root System

• Which root system is easier to transplant? Fibrous roots or tap roots?

• Answer: Fibrous roots

• Why? • Because when plants

are dug up out of the ground, a greater % of the fibrous roots system is saved.

• If a root loses to many root hairs while being transplanted, the plant will die.

• Larger roots only conduct & store water, nutrients, and food

• Root hairs absorb moisture from the ground

Important “Root”words

• Root System– All of the root parts of a single plant collectively

• Primary Root– First root sent from a germinating seed– Absorbs water and nutrients for growing seedling– Anchors seedling in the ground

• Secondary Roots– Small branches that form off of the primary root

Important “Root”words

• Root cap– Group of cells at the end of a root that protect it

from the coarse soil as it pushes through to grow• Adventitious root– Roots that begin growth from a stem or leaf– Commonly found on corn plants

• Basal rooter– Plants that will produce roots at the base of the

stem when a cutting is taken

Important “Root”words

• Root tuber– Enlarged food-storage root with adventitious

shoots that develop– These shoots produce adventitious roots to

produce a new plant