Plant Tissues

3 types of vascular plants tissues

dermal, vascular, and ground tissues

dermal tissue system

forms the outermost layer of plants

2 types of dermal tissue

epidermis and periderm tissue

epidermis

• thin layer of cells 

• covers the entire plant

periderm tissue

• the bark on woody plants

• epidermal is replaced with periderm tissue

• covers the large roots and stems

vascular tissue system

• the transport system that moves water, minerals, and other chemicals around the plant

2 types of vascular tissues

xylem and phloem tissues

xylem tissues

• elongated cells

• transport water and dissolved minerals 

• 1 way flow (upwards from the roots)

  mature xylem 

• hollow (no cytoplasm or organelles) tubes with rigid walls

  • allows water to move easily flow 

• no longer living tissue

phloem tissues

• transports solutions of glucose, dissolved nutrients, and hormones 

• 2 way flow → upwards and downwards

in non-woody plants, xylem and phloem are arranged in…

vascular bundles

ground tissues

• filler between dermal and vascular tissues

• perform a variety of functions such as photosynthesis, store carbohydrates, and provide storage

meristematic cells

meristematic cells are unspecialised cells in plants

2 types of meristematic tissues

apical and lateral meristems

apical meristems (primary growth)

increase the height of the plant

2 types of apical meristems

shoot and root apical meristems

shoot apical meristems

• located on the buds and certain points along the stem (allowing growth of branches)

• more complex than apical meristems at the roots

• buds contain meristem and immature leaf, stem, and sometimes flower parts

root apical meristems

• located on the tips of roots

• further divided into 3 regions:  the meristem region of cell division, elongation, and maturation

explain the 3 regions in root apical meristems

• Division Region: meristem cells first divide at the tips of roots 

• Elongation Region: they begin to elongate, making the roots longer 

• Maturation Region: the cells become differentiated into specialized cells of the dermal, ground, and vascular tissue systems 

  • after cells reach maturation most cells cannot continue to grow or divide 

Lateral meristems (secondary growth)

Lateral meristems are regions of meristematic cells that are found along the sides of stems and roots. They increase the thickness (girth) of the plant. This type of  growth mainly occurs in woody plants.

2 types of lateral meristems

vascular meristem and cork cambium

vascular meristem

inner meristem

what does the vascular meristem produce?

xylem on the inside and phloem on the outside

what happens to the xylem and phloem tissues in vascular meristem?

• xylem accumulates year after year, forming tree rings (used in dendrochronology, the study of tree age) 

• trunk thickens as more xylem is added

• older phloem gets crushed and becomes part of inner bark

cork cambium (Phellogen)

outer meristem

what does cork cambium (or phellogen) produce?

cork (phellem) to the outside and phelloderm to the inside

bark

• cork forms the outer bark, which is protective and waterproof

• together phloem and cork create the bark of the tree

plants that do not contain lateral meristems

• stems and roots cannot grow any thicker once the first tissues formed by the apical meristems have matured

• cannot produce any woody tissue and therefore usually remain quite small

• short-lived annuals, completing their entire life cycle in one year