Identifying Plant Tissues - sps186.org one.pdf · Identifying Plant Tissues Chapter 4 + Combining Cells to Form Tissues ! Plants grow as cells divide to produce new cells in areas

+ Identifying Plant Tissues Chapter 4

+ Combining Cells to Form Tissues

! Plants grow as cells divide to produce new cells in areas of the plant called meristems.

! After new cells are produced, they specialize for certain functions, enlarging and changing their structure to match their function.

! Cells…..tissues…..tissue systems…..organs

+ Four Main Types of Tissue Systems

! Meristematic tissue system- contains cells that are actively dividing to produce new plant tissue

! Ground tissue system- contains tissues that make up the bulk of the plant ! Do photosynthesis ! Support ! Store food ! Repair damage

+ Four Types of Tissue Systems

! Vascular tissue system- conducts water, minerals, and sugars throughout plant

! Dermal tissue system- protect plant and prevents water loss from tissues

+ Meristematic Tissues

! Meristematic tissues are tissues where cells are actively multiplying to provide new cells for plant growth. ! permanent regions of active cell division ! all purpose cells ! can become any type of plant cell ! small, box-shaped, small vacuoles

+ Meristematic Tissues

! As the cells enlarge, they begin to differentiate, becoming specialized for a certain function.

! Two plant organ systems- ! Shoot system- above ground, supports

leaves, flower, and fruits ! Root system- underground, absorbs water

and minerals

+ Meristematic Tissues

! Four types of meristems ! Apical meristems ! Axillary buds ! Lateral meristems ! Intercalary meristems

+ Meristematic Tissue - Apical

! Apical Meristems - Found at the tips of roots and shoots. Plants get taller, and roots get longer, from their tips. ! Increase in length as the apical meristems

produce new cells (primary growth) ! Divide to produce new cells, which elongate,

making roots get longer and shoots get taller. ! Primary Meristems ! Protoderm ! Ground Meristem ! Procambium

+ Meristematic Tissue – Apical

! Once cells elongate and differentiate into a particular cell type, they usually can’t divide any more due to their rigid cell walls.

! Meristematic cells, however, continue to divide, enabling growth throughout the life of the plant. ! Indeterminate growth- keeps growing

throughout life ! Determinate growth- stops growing when

reaches maturity

+ Meristematic Tissues - Lateral

! Lateral meristems are thin cylinders of tissue that form in mature regions of shoots and roots of many plants, especially those that produce woody tissue.

! They divide to produce secondary growth, growth that increases the diameter [girth] of a shoot [stem or trunk] or root.

+ Meristematic Tissues - Lateral

! Plants have two types of lateral meristems. ! Vascular Cambium – Produces new vascular

tissues that function primarily in support and conduction. ! Thin cylindrical cells.

! Cork Cambium - Lies outside vascular cambium just inside the outer bark of woody plants.

+ Meristem

s and G

rowth

+ Meristematic Tissues - Axillary

! Axillary Buds

-- produced as stems elongate in the angle between the stem and the petiole of each leaf

-- May remain dormant until apical meristem has grown and moved away from the axillary bud.

-- When apical meristem is far enough away, the meristems of the axillary bud begins to grow forming a branch.

+ Meristematic Tissue - Axillary

! Branches can be forced to grow by removing the apical meristem which wakes up the axillary meristem of the main shoot.

+ Meristematic Tissues

! Grasses and related plants do not have vascular cambium or cork cambium, but do have apical meristems in the vicinity of the nodes. ! Intercalary meristems ! Develop at intervals along stems where

they add to stem length- cells get added to the middle to increase length

! This is why you can mow grass and the grass will continue to get longer.

+ Intercalary Meristem