Chapter 12.4

Structures of Seed Plants

Food and Water Xylem is a vascular tissue that

transports water and minerals through the entire plant. “roots to shoots”

Phloem is the vascular tissue that transports food molecules to all parts of a plant.

Roots Three main functions of roots

Supply plants with water and dissolved minerals absorbed from the soil. (transported through the xylem)

Hold plants securely in the soil Store surplus food made during

photosynthesis. This is transported through the phloem to the roots and stored as starches and sugars.

Structure of Roots The root surface is covered in cells called

the epidermis. Some of them extend out into root hairs to increase the surface area of the root.

The absorbed water diffuse into the vascular system at the center of the root and are transported to the rest of the plant.

Root Cap The cells at the tip of the root produce a

slimy substance that makes it easier for the root to continue to grow.

Root Systems Two kinds of root systems

Tap Root - has one main root that grows downward

Fibrous Root system – has several roots that spread out from the base of the plant’s stem. Monocot’s usually have fibrous roots

Stems Stems Functions

Support the plant body. Leaves are arranged on the stems or at the end of the stems for photosynthesis

Transport materials between the root system and the shoot system

Some stems store materials. Like cactuses and some trees.

Herbaceous Stems Stems that are soft, thin and flexible.

.

Woody Stems Trees and shrubs with rigid stems made of

wood and bark. These plants have a growing season in

which they produce new xylem cells

Leaves Leaf Functions

Make food for the plant. Chloroplasts in the leaf cells capture energy from sunlight.

They also absorb Carbon Dioxide during the process of photosynthesis

Leaf Structure Their structure is related to their main

function. Cuticle – waxy covering that prevents water

loss Epidermis – a single layer of cells that lies

below the cuticle, light passes through this Stomata – tiny openings in the epidermis

that allow carbon dioxide to enter the leaf Guard cells – open and close the stomata Xylem and phloem – transport water,

minerals and food to and from the leaves. Some leaves have modified functions like

the spines on a cactus

Flowers Flowers are adaptations that aid in

sexual reproduction. Some flowers smell like rotting meat to

attract flies that will spread their pollen. Flowers that, like grass, that lack

fragrances and color rely on the wind to spread their pollen.

Some flowers have nectar with sugars in it that attract insects to spread their pollen

Basic Parts Sepals – are modified leaves that make up

the outermost ring of the flower parts and protect the bud. Sepals are often green like the leaves.

Petals – are broad, flat, think leaf like parts of a flower. They help to attract insects and animals

Stamen – the male reproductive structure of flowers. Each has a think stqalk called a filament which is topped by an anther. Anthers produce the pollen.

Pistil – the female reproductive structure. The tip is called the stigma. This is where the pollen enters and travel down the style. Once it reaches the bottom Ovary the pollen will join with one of the eggs, called ovules, and each ovule will form a seed. The ovary then become a fruit.