Plants Overview
Honors Biology
Mrs. Mawhiney
Fig. 29-7
1 Origin of land plants (about 475 mya)
2 Origin of vascular plants (about 420 mya)
3 Origin of extant seed plants (about 305 mya)
Hornworts
1
Mosses
Pterophytes (ferns,
horsetails, whisk ferns)
3
Angiosperms
450
400
350
300
Millions of years ago (mya)
50
0
Seed plants
Gymnosperms
Vascular plants
2
Seedless
vascular
plants
Lycophytes (club mosses,
spike mosses, quillworts)
500
Land plants
ANCESTRAL
GREEN
ALGA
Nonvascular
plants
(bryophytes)
Liverworts
Seeds
• Seeds changed the
course of plant
evolution, enabling
their bearers to
become the
dominant producers
in most terrestrial
ecosystems
• A seed consists of
an embryo and
nutrients surrounded
by a protective coat
Concept 30.2: Gymnosperms bear “naked”
seeds, typically on cones
• The gymnosperms have “naked” seeds
not enclosed by ovaries and consist of
four phyla:
– Cycadophyta (cycads)
– Gingkophyta (one living species: Ginkgo biloba)
– Gnetophyta (three genera: Gnetum, Ephedra,
Welwitschia)
– Coniferophyta (conifers, such as pine, fir, and
redwood)
Phylum Cycadophyta
• Individuals have large cones and
palmlike leaves
• These thrived during the Mesozoic, but
relatively few species exist today
Fig. 30-5a
Cycas revoluta
Phylum Coniferophyta
• This phylum is by far the largest of the
gymnosperm phyla
• Most conifers are evergreens and can
carry out photosynthesis year round
Fig. 30-5k
Sequoia
Angiosperms
Nonvascular plants (bryophytes)
• Angiosperms
are seed
plants with
reproductive
structures
called flowers
and fruits
• They are the
most
widespread
and diverse of
all plants
Seedless vascular plants
Gymnosperms
Angiosperms
Fig. 30-7
Stigma
Stamen
Anther
Carpel
Style
Filament
Ovary
Petal
Sepal
Ovule
Video: Flower Blooming (time lapse)
Fruits
• A fruit typically consists of a mature
ovary but can also include other flower
parts
• Fruits protect seeds and aid in their
dispersal
• Mature fruits can be either fleshy or dry
Animation: Fruit Development
Fig. 30-8
Tomato
Ruby grapefruit
Nectarine
Hazelnut
Milkweed
Fig. 30-13n
Monocot
Characteristics
Eudicot
Characteristics
Embryos
Two cotyledons
One cotyledon
Leaf
venation
Veins usually
parallel
Veins usually
netlike
Stems
Vascular tissue
scattered
Vascular tissue
usually arranged
in ring
Fig. 30-13o
Monocot
Characteristics
Eudicot
Characteristics
Roots
Taproot (main root)
usually present
Root system
usually fibrous
(no main root)
Pollen
Pollen grain with
one opening
Pollen grain with
three openings
Flowers
Floral organs
usually in
multiples of three
Floral organs usually
in multiples of
four or five
Monocots
• More than one-quarter of angiosperm
species are monocots
Fig. 30-13e
Orchid
Fig. 30-13f
Eudicots
• More than two-thirds of angiosperm
species are eudicots
Fig. 30-13h
California poppy
Fig. 30-13j
Dog rose
The plant body has a hierarchy of
organs, tissues, and cells
• There are three
basic plant organs:
– Roots
– Stems
– Leaves
Shoot System:
Stems and
Leaves
Reproductive shoot (flower)
Apical bud
Node
Internode
Apical
bud
• Stems – function
primarily to display
the leaves.
– Terminal Bud –
area of growth at
the top end of stem
– Axillary Buds –
area of growth
located in the V
area between the
leaf and the stem
(branches)
• Leaves – main
photosynthetic organ
in plants
Vegetative
shoot
Leaf
Shoot
system
Blade
Petiole
Axillary
bud
Stem
Taproot
Lateral
branch
roots
Root
system
There are three basic groups of
plant tissues:
• Dermal Tissue
– Single layer of closely packed cells
– Protects plant against water loss and
invasion by pathogens and viruses
– Cuticle – waxy layer in leaves
• Vascular Tissue
– Xylem and phloem
• Ground Tissue
– Any tissue that’s not Dermal or
Vascular tissue
– Pith – ground tissue located inside
vascular tissue
– Cortex – ground tissue located
outside the vascular tissue
Transport in Xylem and Phloem
Vascular plants have two types of vascular tissue: xylem
and phloem
• Xylem conducts most of the
water and minerals and
includes dead cells called
tracheids
• Water-conducting cells are
strengthened by lignin and
provide structural support
• Increased height was an
evolutionary advantage
• Phloem consists of living cells and
distributes sugars, amino acids,
and other organic products
• Sugar-Conducting Cells of the
Phloem
• Sieve-tube elements are alive at
functional maturity, though they
lack organelles
• Sieve plates are the porous end
walls that allow fluid to flow
between cells along the sieve tube
• Each sieve-tube element has a
companion cell whose nucleus
and ribosomes serve both cells
Vegetative Propegation
Types of Veg.
Propagation
Description
Examples
Bulbs
Short Stems
Underground
Horizontal Stems
above ground
Onions
Underground
Stems
Cut a stem and
attach it to a
closely related
plant
Potatoes
Runners
Tubers
Grafting
Strawberries
Seedless Oranges
Tropical Tropisms
tropism – turning response to a
stimulus
Phototropism
Refers to how plants respond to
light
Gravitropism
Refers to how plants respond to
gravity
Thigmotropism Refers to how plants respond to
touch (IVY, strangler trees
Auxins
Responses are initiated by
hormones. Major plant hormones
belong to the class AUXINS