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Chapter 28: Flowering
Plants
Most of your notes for this Chapter will be found in your
Flowering Plant Lab. However, here are some notes in addition
to your lab.
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Angiosperms have dominated
earth for 60 million years;
250,000 million species are
known today.
Monocots include orchids,
palms, lilies, grains, grasses.
Dicots include shrubs, trees
(except for conifers),
ornamental plants, many food
crops.
Know traits of each! (Lab) &
See left.
3 Plant organs: roots, stems,
leaves (Lee also lab)
1. Roots: Root hairs-increase
surface area of root for
absorption
Large taproots - store food
such as starch for plant (Ex:
carrots, turnips, sugar beets,
sweet potatoes.)
2. Stems - Terminal bud is at apex of stem
when plant stem is growing in length.
Axillary buds, in angle formed by a leaf
and stem) are dormant.
Terminal bud produces hormones
inhibiting growth of axillary buds = apical
dominance, so plant can grow up to sun.
Axillary buds begin growing and develop
into branches under certain conditions.
What is “pinching back?”
3 kinds of Modified stems:
Runner in a strawberry plant = horizontal
stem - new plants emerge from tip of
runner = asexual reproduction
Rhizome of an iris plant =horizontal
underground stems = store food, & can
bud new plants
Tubers are rhizomes ending in enlarged
structures (potatoes). Eyes of potato are
axillary buds, can grow when planted.
3. Leaves - flat blades (for light collection) and
petioles (joins leaf to stem.) Celery is a big
petiole.
Tendrils = modified leaves for climbing
and support .
Spines of a cactus = modified leaf parts
protecting plant. Cactus stem is
photosynthetic.
• Plant Cells - have chlorophyll, large
central vacuole, some have a multipart cell
wall:
• Primary cell wall - laid down first
• Secondary cell wall - deposited between
plasma membrane and primary wall, more
rigid for support
• Parenchyma cells - most abundant cell, for
food storage, photosynthesis. Only primary
cell walls.
• Collenchyma cells - provide support in
growing parts of plant. Only primary cell
walls.
• Sclerenchyma cells - have thick secondary
walls with lignin (wood). When mature,
most are dead - rigid cells support plants.
Make rope and clothing.
• 2 Plant Vascular Tissues:
1. Xylem - contains water conducting cells move water & minerals up stem
2. Phloem -contains food conducting cells transport sugars from leaves or storage tissue
to other parts of plant
• 3 Tissue Systems continuous throughout
plant:
1. Dermal-covers, protects, waxy coating
(epidermis)
2. Vascular- xylem and phloem; support,
transport
3. Ground - bulk of young plant, fills spaces
between epidermis and vascular.
Photosynthesis, storage, support.
Types of ground tissue:
Cortex - in root,cells store food, take up
water & minerals.
Endodermis - selective barrier in cortexdetermines which substances pass between
cortex and vascular tissue.
Pith - fills center of stem in dicots, food
storage.
(Con’t.)