Roots, Stems, and Leaves: Section 4

Annual Rings

A pattern of circles inside woody stems. The rings are made up of xylem: each ring represents one year.

Photosynthesis Equation

Carbon dioxide + water (sunlight) = sugar + oxygen

Woody Stems

Contain many layers of tissue from the outer layer of bark to the inner layer of heartwood

Fibrous root characteristics

Fibrous root systems consist of many similarly sized roots which form a dense and tangled mass.

Two main types of root systems

Fibrous roots and taproot systems

Herbaceous Stems

Herbaceus stems contain no wood and are often soft.

The leaf and photosynthesis

Leaf structure is ideal in carrying out photosynthesis. The cells which contain the most chloroplasts are located near the upper surface of the leaf. Chlorophyll in the chloroplasts traps the sun's energy. CO2 enters the leaf through the open stomata. H2O which is absorbed in plant's roots travels up past the stem to the left through xylem. O2 and sugar are produced form photosynthesis, so O2 exits leaf through open stomata. The created sugar travels through phloem throughout the plant.

Controlling water loss

Plants have a way to prevent to much water loss through transpiration. One way to retain water is by closing the stomata. Cuticles also prevent water loss.

Root hairs

Root hairs grow out of the root's surface and can enter spaces between soil particles. There they absorb water ad minerals. By increasing the surface area of the root that touches the soil root hairs help the plants absorb large amounts of water and other substances.

Root Functions

Roots anchor a plant in the ground, absorb water and minerals from the soil, and sometimes store food

Stem Structure

Stems consist of vascular tissue along with many supporting cells. Bundles of xylem and phloem run all the way up the stem- from the roots to the leaves. The bundles of tissue can either be scattered randomly throughout the stem or arranged in rings depending upon the type of plant.

Taproot characteristics

Taproot systems have one long and thick main root

Woody stem make-up

The outmost layer is the bark which includes an outer protective layer of tissue and an inner layer of phloem which transports food from the stem.The next layer is a layer of cells called cambium which divide to make new xylem and phloem. Sapwood is active xylem that transports water and nutrients through the stem. The heartwood is not active but is support to the plant. -Xylem is what makes up most of the "wood".

Transpiration

The process by which water evaporates from leaves

Root cap

The root cap protects the root from injury from rocks as the root grows into the soil

Plant stem functions

The stem produces branches, leaves, and flowers. Carries substances between the plant's roots and leaves. Provides support for the plant and holds up the leaves for exposure to the sun. (some stems store food)

Leaf structure

The structure of leaves is adapted for capturing the sun's energy and carrying out photosynthesis. A leave's top and bottom surface layers protect the cells inside. Between cell layers are veins which contain xylem and phloem. On the surface layers of a leaf are stomata: pores which open and close to control when gas enters and exits the leaf

Vascular Tissue

The vascular tissue is located in the center of the root. There the absorbed water and nutrients speedily travel to the xylem. The substances are then transported up to the stems and leaves. Phloem transports the food made in the leaves of the plant to the roots. The root tissues amy use the food for growth or store it for later use.