Plant Cells and Tissues 21.1

3 tissue systems.

Dermal, Ground Vascular Tissue System

Plasmodesmata

Connects neighboring cells strands of cytoplasm that pass through openings in cell walls and connect living cells. Allows cells of a plant tissue can share water, nutrients, and chemical signals

Dermal Tissue System

Covers outside of plant and protects it in a variety of ways. called epidermis is made up of live parenchyma cells in the nonwoody parts of plants. On leaves and stems, epidermal cells may secrete a wax-coated substance that becomes the cuticle. Dermal tissue made of dead parenchyma cells makes up the outer bark of woody plants.

Ground Tissue System

Dermal tissue surrounds the system of ground tissue, which makes up much of the inside of a plant. provides support and stores materials in roots and stems. In leaves, ground tissue is packed with chloroplasts, where photosynthesis makes food for the plant. consists of all three of the simple tissues—parenchyma, collenchyma, and sclerenchyma tissue—but parenchyma is by far the most common The ground tissue of cacti has many parenchyma cells that store water. However, the spines of cacti—which are actually modified leaves—contain mostly rigid sclerenchyma cells in their ground tissue

Tissue

Is a group of cells working together to perform a certain function.

Phloem

Is the vascular tissue that carries the products of photosynthesis through the plant.

Xylem

Is the vascular tissue that carries water and dissolved mineral nutrients up from the roots to the rest of the plant.

Three basic types of plant cells

Parenchyma cells Collenchyma cells Sclerenchyma cells

Vascular Tissue System

Surrounded by ground tissue, transports water, mineral nutrients, and organic compounds to all parts of the plant. made up of two networks of hollow tubes like our veins and arteries. Each network consists of a different type of vascular tissue that works to move different resources throughout the plant: Xylem and Phloem

plant cells have

cell walls, plastids, and a large vacuole

Collenchyma cells

has cell walls that range from thin to thick, providing support while still allowing the plant to grow. These cells are most common in the younger tissues of leaves and shoots. They often form into strands. (celery strings) They are flexible. walls don't contain lignin, so they are stretchy and can change size. As a young leaf grows, collenchyma cells can elongate and still give the leaf structure

Sclerenchyma cells

is the strongest. have a second cell wall that is hardened by lignin, which makes these cells very tough and durable. But the lignin also makes these cells very rigid. Unlike collenchyma cells, they can't grow with the plant. are found in parts of the plant that aren't lengthening anymore. die when they reach maturity. The cytoplasm and organelles of these dead cells disintegrate, but the rigid cell walls are left behind as skeletal support for the water-conducting tissues or for the plant itself. form a major part of fruit pits and the hard outer shells of nuts. found in stems and leaf veins and are responsible for the gritty texture of pears. Humans use sclerenchyma cell fibers to make linen and rope

Parenchyma cells

the most common type of plant cell. stores starch, oils, and water for the plant. You can find parenchyma cells throughout a plant. have thin walls and large water- filled vacuoles in the middle. Photosynthesis occurs in green chloroplasts within parenchyma cells in leaves. Both chloroplasts and colorless plastids in parenchyma cells within roots and stems store starch. The flesh of many fruits we eat is also made of parenchyma cells. They have the ability to divide throughout their entire lives, so they are important in healing wounds to the plant and regenerating parts. For example, parenchyma cells let you place stem cuttings of many types of plants in water to grow into a complete, new plant have thin and flexible cell walls that can change shape