Transcript Plant Reproduction & Development

Plant Structure, Growth, &
Development
The Diversity of Angiosperms
 Angiosperms
(flowering plants) can
be divided into 2
major categories:
Monocots –
 have one seed leaf
(cotyledon)
Dicots –
 have 2 seed leaves
(cotyledons)
Monocots
 Monocots have only 1 cotyledon (seed leaf)
 Examples of monocots:
Corn, wheat, lilies, orchids, palms
Dicots
 Dicots have 2 cotyledons (seed leaves)
 Examples of dicots:
Roses, clover, tomatoes, oaks, daisies
Woody vs. Herbaceous Plants
Angiosperms can also be subdivided into
the groups of woody and herbaceous
plants
Woody plants are made of cells with thick cell
walls that support the cell body
Examples: trees, shrubs, vines
Herbaceous plants do not produce wood as
they grow, and instead have smooth stems
Examples: dandelions, sunflowers
Plant Life Spans
 Most plants experience indeterminate growth
They continue to grow as long as they live
 The lifespan of plants, however, is genetically
determined
Annuals – complete their life cycle in 1 year
 Examples: marigolds, cucumbers (lots of garden plants)
Biennials - complete their life cycle in 2 years
 Year 1: germinate & grow roots
 Year 2: grow stems & leaves, produce flowers & seeds
 Examples: evening primrose, celery
Perennials – live for more than 2 years
 Examples: Maple trees, grasses, palm trees
Plant Structure
 Plants are made up of
a root system and a
shoot system
The Root System
 What do roots do?
Anchor the plant in the soil
Absorb minerals and water
Store food
 Types of root systems
Fibrous root system
 Found mostly in
monocots
Taproot system
 Found mostly in dicots
How do roots grow?
 There are 3 distinct zones in a
plant root where different
things are taking place
 Zone of cell division
 Includes the apical
meristem
• Produces new cells by
mitosis
 Zone of elongation
 Cells get longer
 Zone of maturation
 The cells differentiate and
become specialized
 The root is protected by a root
cap, which protects the apical
meristem as the plant grows
down into the soil
The Shoot System
 The shoot system
consists of:
 vegetative shoots (which
bear leaves)
 floral shoots (which bear
flowers)
 Stems have 3 important
functions:
 Producing leaves, flowers,
branches
 Holding leaves up to the
sunlight
 Transporting substances
between roots and leaves
How do stems grow?
 Primary growth
Increase in length
Occurs by cell divisions in
apical meristem (at top
of shoot)
 Secondary growth
Increase in width
Occurs by cell divisions in
the lateral meristems
(also known as vascular
cambium)
Apical Meristems
The Shoot System: Leaves
 Leaves are attached
to stems at nodes
 The area between 2
nodes is called an
internode
The Shoot System: Leaves
 Leaves are the primary
photosynthetic organs of
most vascular plants
 Most leaves have a
flattened blade and a
petiole, which is the
stalk that attaches the
leaf to the stem
Tissue Systems in Plants
 All 3 plant organs
(root/stem/leaf) have
dermal, vascular, and
ground tissue systems
 Dermal Tissue System
 Outer protective
covering, similar to our
skin 
 Protects the plant from
water loss and disease
 The cuticle is a waxy
coating that helps to
prevent water loss
Tissue Systems in Plants
 Vascular Tissue System
 Carries out long-distance
transport of materials within
the plant
 Xylem and phloem are
examples of vascular tissues
 Ground Tissue System
 Pith (inside vascular tissue)
and cortex (outside vascular
tissue) are examples of
ground tissue
 Includes cells specialized for
storage, photosynthesis, and
support
Flower Structure
 Flowers are the
reproductive structure
of angiosperms
 Sepals:
Enclose the bud before
it opens
Protect flower while it’s
developing
 Petals:
Usually brightly colored
to attract pollinators
Flower Structure
 Stamens:
The male portion of a
flower
Made up of an anther
and a filament
The anther produces
haploid pollen grains by
meiosis
Most flowers have
multiple stamens
Flower Structure
 Carpels/Pistils:
The female portion of a
flower
Stigma:
 Sticky – to trap pollen
Style:
 Hollow tube which
connects stigma and
ovary
Ovary:
 Produces female
gametes (ovules)
Monoecious and Dioecious Species of Plants
 Monoecious
“one house”
Has both male and
female flowers on a
single plant
 Dioecious
“two houses”
Male and female parts
are found on separate
plants