Lesson Overview Lesson Overview Specialized Tissues in Plants Lesson Overview Lesson Overview Specialized Tissues in Plants Lesson Overview 23.1 Specialized Tissues in Plants

Lesson Overview Lesson Overview Specialized Tissues in Plants THINK ABOUT IT Have you ever wondered if plants were really alive? Indeed they are—if you look deep inside a living plant, you will find a busy and complex organism. Plants move materials, grow, repair themselves, and constantly respond to the environment. Their cells and tissues work together in very effective ways. The leaves of this sundew plant are adapted to capture and digest live prey.

Lesson Overview Lesson Overview Specialized Tissues in Plants Seed Plant Structure The three principal organs of seed plants are roots, stems, and leaves.

Lesson Overview Lesson Overview Specialized Tissues in Plants 1)Roots anchor plants in the ground, holding soil in place and preventing erosion absorb water and nutrients store food hold plants upright against forces such as wind and rain

Lesson Overview Lesson Overview Specialized Tissues in Plants 2) Stems support system for the plant body transport system lifts water from the roots up to the leaves carries the products of photosynthesis from the leaves down to the roots

Lesson Overview Lesson Overview Specialized Tissues in Plants Stems defensive system that protects the plant against predators and disease produce leaves and reproductive organs such as flowers.

Lesson Overview Lesson Overview Specialized Tissues in Plants 3) Leaves main photosynthetic organs have adjustable pores to conserve water while letting oxygen and carbon dioxide enter and exit the leaf from the dry air

Lesson Overview Lesson Overview Specialized Tissues in Plants Plant Tissue Systems What are the primary functions of the main tissue systems of seed plants? Dermal tissue = protective outer covering Vascular tissue = supports the plant body and transports water and nutrients Ground tissue = produces and stores sugars, and supports the plant

Lesson Overview Lesson Overview Specialized Tissues in Plants Can you identify the 3 layers in each part of the plant?

Lesson Overview Lesson Overview Specialized Tissues in Plants Dermal Tissue epidermis = single layer of cells that makes up dermis in younger plants In older plants, dermal tissue may be many cell layers deep and may be covered with bark cuticle = thick waxy layer covering epidermis that protects against water loss

Lesson Overview Lesson Overview Specialized Tissues in Plants Vascular Tissue 1.Xylem = water-conducting tissue 2.Phloem = carries dissolved food Both xylem and phloem consist of long, slender cells that connect almost like sections of pipe, as shown in the figure.

Lesson Overview Lesson Overview Specialized Tissues in Plants Xylem cell walls of xylem contain lignin, a complex molecule that gives wood much of its strength

Lesson Overview Lesson Overview Specialized Tissues in Plants Ground Tissue produces and stores sugars contributes to physical support It is neither dermal nor vascular. Three types of ground tissue:

Lesson Overview Lesson Overview Specialized Tissues in Plants Ground Tissue 1) Parenchyma cells = thin cell walls and large central vacuole main type of ground tissue In leaves, these cells contain many chloroplasts and are the site of most of a plant’s photosynthesis.

Lesson Overview Lesson Overview Specialized Tissues in Plants Ground Tissue 2) Collenchyma cells = strong, flexible cell walls that help support plant organs

Lesson Overview Lesson Overview Specialized Tissues in Plants Ground Tissue 3) Sclerenchyma cells = extremely thick, rigid cell walls that make ground tissue such as seed coats tough and strong.

Lesson Overview Lesson Overview Specialized Tissues in Plants Plant Growth and Meristems Even the oldest trees produce new leaves and new reproductive organs every year, almost as if they remained “forever young.” The secrets of plant growth are found in meristems. Meristems = regions of unspecialized cells in which mitosis produces new cells that are ready for differentiation.

Lesson Overview Lesson Overview Specialized Tissues in Plants Meristems and Flower Development Meristems are found in places where plants grow rapidly, such as the tips of stems and roots and also in highly specialized cells found in cones and flowers