12.2 - Leaves

Blade

The flat part of a leaf.

Peticole

The part of the leaf that attaches it to the stem.

Function of leaves

Leaves carry out photosynthesis, gas exchange, and protect the plant.

Cuticle

A waxy structure that provides waterproofing, protection, and prevents water loss in leaves.

Epidermis

A single layer of tightly packed, transparent cells that allows light to pass and serves as a protective barrier.

Palisade mesophyll

A layer of cylindrical cells full of chloroplasts that captures light for photosynthesis.

Stomata

Openings controlled by guard cells, primarily on the lower epidermis, facilitating gas exchange and preventing water loss.

Vascular bundle

Structures made of xylem and phloem responsible for transport and the arrangement of veins in the leaf (venation).

Mesophyll

The middle part of the leaf where materials for photosynthesis are stored.

Human uses of leaves

Leaves are used for food, tea, wax for industrial products, construction, religion, and medicine.

Non-toxic leaves

Leaves and chemicals that can treat cancers and heart disease.

Toxic leaves

Leaves like rhubarb that are harmful to humans.

Psychotropic chemicals

Chemicals from plants that can alter the mind, increase appetite, decrease nausea, and reduce muscle spasms.

Coca plants

Plants that yield cocaine when isolated; used medicinally in the past, can increase alertness and breathing rate.

Photosynthesis

The process by which leaves capture sunlight to convert carbon dioxide and water into glucose and oxygen.

Gas exchange

The process of swapping oxygen and carbon dioxide in and out of the leaf through stomata.

Chlorophyll

The green pigment in chloroplasts that is essential for photosynthesis.

Cuticle wax

A substance derived from the leaf's cuticle used in products like cars, surfboards, and cosmetics.

Xylem

The part of the vascular bundle that transports water and nutrients from the roots to the plant.

Phloem

The part of the vascular bundle that transports sugars and metabolic products downward from the leaves.

Venation

The arrangement of veins in a leaf, critical for transport and structural integrity.