identifying plant tissues - sps186.org one.pdf · identifying plant tissues chapter 4 + combining...
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+ 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