Roots, Stems, and Leaves

Roots• Types of roots

– Taproot: primary root that grows longer and thicker than the secondary roots (grows deeper)

• ex. carrots

– Fibrous roots: wide branching of roots with no single root larger than rest (grows shallow)

• ex. grasses

Roots• Functions:

– anchor plants in soil– absorb water and nutrients from soil

• Nutrients are dissolved in the water

– store carbohydrates that plant can use later• Ex. Beets, radishes, and carrots

Root adaptations

• Root cap: protective cap on tip of the root; secretes wax to help root move through soil

• Root hairs: fine, hair-like extensions of root; increases surface area for greater water absorption

• Nodules: found on roots of some plants like bean plants; where symbiotic nitrogen-fixing bacteria live

Stems

• Functions:– Support leaves– Transport materials between

roots and leaves– Storage site for nutrients

Leaves

• Structure:– Simple leaf: a leaf with one single blade– Compound leaf: a leaf blade that is divided into

several leaflets

Simple leafCompound leaf

leaflets

Leaves• Function:

– Primary site for photosynthesis• Converts energy from sunlight into food source

(glucose)• Occurs in cell organelles called chloroplasts

– Site for gas exchange (oxygen/carbon dioxide)• Occurs through stoma (singular: stomata) which are

openings in leaves

chloroplast

stoma