Specialized Tissues in Plants
Seed Plant Structures
§ Seed plant cells are organized into three different tissues and organs:
§ Linked together by systems that run the length of the plant performing functions such
v Coordinating plant activities
water and dissolved nutrients
plants in the ground, hold soil in place, and prevent erosion
system for the plant body
system that carries nutrients
system that protects the plant against predators and disease
1. main photosynthetic
subsystems to protect against water loss
Plant Tissue Systems
§ Plants consist of three main tissue systems:
1. dermal tissue - like the "skin" of a plant
or the outermost layer of cells
2. vascular tissue - like the plants "bloodstream",
transporting water and
and nutrients throughout the plant
3. ground tissue - everything else!
§ Dermal tissue (outer covering of a plant) consists of a single layer of epidermal cells, and covered with the cuticle, a thick waxy coating that protects against water loss.
1. Trichomes are tiny projections which protect the leaf and give it a
2. Root hair cells provide a large amount of surface area and aid in water
3. Guard cells are on the underside of leaves and regulate water loss
and gas exchange.
§ Vascular tissue forms a transport system that moves water and nutrients throughout
§ Principle subsystems are:
1. Xylem - a water-conducting tissue
w Consists of tracheids
(long, narrow cells with walls that are impermeable to water) and vessel
elements (wider than tracheids and stack on top of one another for continuous water flow)
2. Phloem - a food-conducting tissue
w Consists of sieve tube
elements, (arranged end to end and form a pipeline which sugars and other foods flow through) and companion cells (surround sieve tube elements and support phloem cells)
§ They are both a network of hollow connected cells that carry fluids throughout the
tissue lies between dermal and vascular tissues.
is the main type of ground tissue.
have thin cell walls and large central vacuoles
w in leaves,
they are packed with chloroplasts and the main site of photosynthesis
is thicker, strong, flexible cell which supports larger plants.
up the "strings" of a stalk of celery
is an extremely thick, rigid cell that makes ground tissue tough and strong.
Plant Growth and Meristematic Tissue
plants have indeterminate growth, which means they
grow and produce new cells at the tips of their roots and stems for as long as they live.
§ Meristems are clusters of tissue that are responsible for continuing growth throughout a plant's lifetime.
§ Meristemtic tissue are the new cells produced and are undifferentiated (no specialized function yet).
PLANT TISSUE THAT PRODUCES NEW CELLS BY MITOSIS.
§ Apical meristem
is a group of undifferentiated cells that divide to produce increased length of stems and roots.
is the process where cells develop into mature cells with specialized structures and functions.
dermal, ground and vascular tissue
plants also grow in width as a result of meristematic tissue that lines the stems and roots of a plant.