Ch. 35: Plant Structure and Growth. The Plant Body A. Consists mainly of three parts: 1. Roots 2. Stems 3. Leaves B. Comparison of monocots v. dicots. The basic morphology of a plant has two systems: 1. Root System : anchor the plant in the soil,
Ch. 35: Plant Structure and Growth
Root hairs are made up of epidermal
cells and are one-cell thick.
Stolons allow for asexual reproduction.
Daughter plants are clones of the mother
Simple v. Compound: simple leaves
have a single, undivided blade, while
compound leaves have several leaflets
attached to the petiole.
Cling to support
To attract pollinators
Covers and protects
“filler tissue”; neither dermal
nor vascular; diverse functions such as
photosynthesis, storage, and support.
to vascular tissue
-Pith: internal to
in a plant body:
(Protoplast: Plant cell minus the cell wall)
F. THREE TYPES OF PLANT CELLS:
-thin and flexible; most parenchyma cells lack
a tough secondary cell wall.
-most of the metabolic functions occur in
these cells; photosynthesis takes place in the
parenchyma cells of the leaf.
-support young parts of the plant shoot.
-lack secondary cell walls; allows for plant
growth, while providing structural support.
-many are dead at functional maturity, but
they produce the
secondary walls before
the protoplast dies;
serves as a “skeleton”
that supports the plant.
-2 types of sclerenchyma
1.Fibers: tough, long
and slender; in groups
shape; gritty texture in
A.Most plants continue to grow: “indeterminate
B.Flowers and leaves undergo “determinate
C.Life cycles of plants:
1.Annuals: Plants that complete their life cycle
in a single year or less; food crop.
2.Biennials: life span 2 years, between
germination, growth, and flowering.
3.Perennials: live many years; trees, shrubs,
and some grasses.
D. Meristem: perpetual embryonic tissue;
continual growth by cell division.
1. Apical meristem: shoots and roots
2. Lateral meristems: Secondary growth
progressive thickening of roots and
shoots in woody plants.
E. Primary growth in roots:
1. Root cap: protection of meristem
2. Zone of cell division: apical meristem
3. Zone of elongation: cells elongate; push
4. Zone of maturation: differentiation of cells
(3 tissue systems)
F. Primary tissues in the roots:
1. Stele: vascular bundle (xylem and phloem)
2. Pith: core; parenchyma cells
3. Cortex: region between stele and epidermis;
innermost layer is called endodermis, which
forms the boundary between cortex and stele.
4. Lateral roots: arise from the pericycle
(outermost layer of stele).
Pericycle cells become meristematic and
start to divide, pushing through the cortex.
G. Primary tissue of stems:
1. Vascular bundles (xylem and phloem)
surrounded by ground tissues, pith and cortex.
2. Mostly parenchyma; some collenchyma and
sclerenchyma for support.
H. Primary tissues in leaves:
1. Epidermis: cuticle; protection and to
2. Stomata: tiny pores for gas exchange and
3. Guard cells: specialized epidermal cells
4. Mesophyll cells: ground tissue
(palisade and spongy
Secondary growth is rare in monocots
-A cambrium cell divides into a cambrium
cell and a derivative cell, which will
differentiate into xylem or phloem.
-As layers of xylem are added, stems
increase in diameter.
Secondary xylem forms to
the interior and secondary
phloem to the exterior of
the vascular cambium.
over the years,
layer upon layer
of secondary xylem
producing the tissue
we call wood.
These are the
lines you count to
estimate the age
-Lenticils are splits develop in the periderm
because of higher local activity of the cork
-Bark refers to all tissues external to the
vascular cambium, including secondary
phloem, cork cambium, and cork.
-Only the youngest secondary phloem,
internal to the cork cambium, functions in
-Older phloem dies and sloughs off as
-After several years of growth, several
zones are visible in the stem.
a. Two zones of xylem:
-Heartwood (dead; structural purpose)
b. Vascular cambium
c. Living phloem
d. Cork cambium
into a ring called
the formation of