Download Plant Cells and Tissues Lecture File

Plant Cells and Tissues
Plant Cells and Tissues
Parenchyma: Large, loosely-packed cells,
often cube-shaped, large central vacuole,
thin cell walls, metabolic functions, storage
of water & nutrients.
Collenchyma: Cells w/ irregular shape,
thick cell walls for flexible support of
actively growing regions, form long
strands, help plant withstand wind.
Sclerenchyma: Cells w/ thick, rigid cell walls,
support and strengthen the plant where
growth no longer occurring, like seed coats &
cactus spines.
Dermal Tissue System: forms the outside
covering of plants, functions in absorption,
protection, and/or gas exchange.
Epidermis: Outer layer of dermal tissue
system, made of parenchyma cells.
Cuticle: Waxy outer covering of dermal
tissue, prevents water loss.
Ground Tissue System: immediately inside
dermal tissue, has all 3 types of plant cells,
functions in storage, photosynthesis/
metabolism, and/or support.
Vascular Tissue System: functions in
transport and support.
Xylem: Transports water and minerals
from roots upward, cells dead at
maturity, forms the wood of trees.
Xylem made of two types of
sclerenchyma cells: tracheids and
vessel elements.
Tracheids – have tapered ends that mesh
to form long tubes. Water moves from one
to the next through pits:
Stacked end-to-end, vessel elements
form vessels.
Phloem: Transports organic compounds and
some minerals (in solution) throughout
plant, cells alive at maturity.
Phloem composed of sieve tube
members stacked end-to-end to form
sieve tubes.
Companion cells: Specialized
parenchyma cells that assist with
transport through sieve tube members.
Fibers: sclerenchyma cells contained in
phloem, important in making textiles,
rope.
Meristems: Site of continuously dividing
cells, where growth occurs in plants.
Apical meristems: at tips of stems and
roots, where plants grow in length.
Intercalary
meristems:
Specialized zones
of growth above
the bases of
leaves and stems
in monocots.
Blame these the
next time you
have to mow the
grass!
Lateral meristems: allow
gymnosperms and most dicots to
increase in diameter.
Vascular cambium: Located between
xylem and phloem, produces
additional vascular tissue.
Cork cambium: Located outside phloem,
produces cork which replaces epidermis in
woody stems, protects the plant.
Primary growth increases length, produced
by apical and intercalary meristems.
Secondary growth increases diameter,
produced by lateral meristems (vascular
cambium and cork cambium).