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Ch. 35
Plant Structure and Growth
• I. Angiosperm Body
•
A. Two types
1. Monocotyledon (monocot)
a. One cotyledon, veins in leaf parallel, vascular bundles
are complex, fibrous roots and petals in threes
2. Dicotyledon (dicot)
a. Two cotyledons, veins are netlike bundles arranged in
ring, taproot and petals in four or five
•
B. Plant Morphology
1. Soil provides water and minerals
a. The root system provides access to soil
2. Air provides carbon dioxide
a. The shoot system provides access to air
3. Vascular Tissue- present in both shoots and roots.
a. Xylem- transports water and minerals
1.Tracheids are long and thin, they function in mineral
and water transport.
2. Vessel elements form xylem.
d. Phloem- transports sucrose
1. Sieve-tube members are chains of cells that transport
sucrose.
2. Companion cells hang out with the sieve-tube cells and
help load the sucrose.
4. Roots
a. Taproot-One large root with smaller roots
b. Fibrous root- mat of thin roots
c. Root hairs- tiny hairs that increase surface area
5. Shoots system
a.
b.
c.
d.
Nodes- point at which leaves are attached
Internodes- between nodes
Axillary bud-potential to form new branch, usually dormant
Terminal bud (apex)
1. When a terminal bud grows and inhibits an axillary
bud it is called apical dominance.
e. Leaves- the main photosynthetic organ
5. Plant tissues
a. Parenchyma cells- these are the least specialized cells
1. Perform most of the metabolic functions in a plant, like
photosynthesis
2. They are like animal stem cells
b. Collenchyma cells- they have thicker cell walls
1.They support young parts of the plant
2. The strings of a celery stalk
c. Sclerenchyma- they have lots of lignin, making them very
rigid.
1. Fibers and sclereids are the two types of cells. Fibers
are long and slender while sclereids are short.
2. Rope is made from fibers and nutshells are made
from sclereids.
6. Dermal Tissue
a. Epidermis- a top layer of cells
1. Waxy cuticle-secreted from epidermal cells
2. Root hairs- grow out of epidermal cells
C.Plant Growth
1. Annual- complete lifecycle from germination of seed to death
2. Perennial- live for many years
3. Meristem is a region of growth
a. Apical meristem is located at the tip of roots
and buds of shoots.
1. It is about plant elongation and is
called primary growth.
2. Only happens in the young parts of
the plant
b. Lateral meristems found along the
older part of roots and stems
1. Woody plants have secondary growth
which produces secondary roots and
vascular tissue. It’s about plant girth.
2. Make up bark of tree.
4. Primary growth
a. Roots
1. Root tip secretes polysaccharide that helps it through
the soil
2. Zone of elongation cells here are stretching to 10
times their normal length
3. Zone of maturation is where the cells differentiate.
b. Shoots- follows the same ideas as roots growth
1. Vascular bundles made from _xylem and phloem.
c. Leaves
1. Stomates and guards cells – allow for transpiration
2. Mesophyll is made mainly of parenchyma cells.
• 5. Secondary growth
a. Vascular cambium- forms secondary vascular tissue
b. Cork Cambium- secondary epidermis