Domain Eukarya
Kingdom Plantae
What makes a plant a plant?
• Cell wall primarily of cellulose
• Starch as primary
photosynthetic storage product
• Multicellular with complex
specialized tissue development
• Chl a, Chl b, xanthophylls,
carotenoids
Plant evolution simplified
Radiates from simple to more
complex – in both form
and environments
• Seedless non-vascular
• Seedless vascular
• Seed producing, vascular
• Seed producing, vascular,
fruits/flowers
Semi-aquatic to more terrestrial
• Ancestral “plants”
 transitions to primitive plants
– Requirements met from aquatic environment
• Gas, water, light, buoyancy support
• Complex plants
– Adapt to two environments
• Shoot system
• Root system
Plants: categorized by structures
and lifecycles…
Alternation of Generations
Moss sporophytes and gametophytes
sporophytes
gametophytes
Moss antheridia
Sperm
Moss
antheridia
w/sperm
Moss archegonia
ovum
Moss archegonia 2
ova
Moss archegonia 3
Moss sporophytes
Operculum
Moss capsule
(sporophyte)
Spores
Liverwort
Liverwort antheridiophore
Liverwort antheridiophore 2
Liverwort antheridia
Antheridiophore
sperm
Liverwort antheridia w/sperm
Liverwort archegoniophore
Liverwort archegonia w/ova
Archegoniophore
ovum
Archegonium
Liverwort sporophyte
Archegoniophore
Liverwort
sporophyte 2
spores
Liverwort gemmae cups(cupules)
Gemmae cups (cupules)
Gemma cup
(cupule)
gemma
Hornwort
sporophytes
gametophyte
Hornwort 2
“Horn –like”
Sporophyte
gametophyte
Tracheophytes
• Ferns and “fern allies”
• Seedless
• Vascular plants
– Xylem composed of
Tracheids – tapered
porous cells
• capillary action
moderately efficient
• Sporophyte dominant
ancestral e.g. Rhyniophyta
Psilophyta
Psilophyta gametophyte
Lycophyta
strobila
leaves
Lycophyta strobilus
microspores
sporophylls
megaspores
Lycophyta strobilus 2
Megaspores
megsporangium
Microspores
Lycophyta gametophyte
Sphenophyta
strobilus
Sphenophyta strobilus
Sphenophyta gametophyte
Pterophyta sporophyte
Pterophyta sporophyte2
Fern frond w/
sori
Sori on fern leaflets
Sorus
Fern sporangia
Spores
Annulus
Sporangium
Fern sporangia and spores
Fern gametophyte
Fern gametophyte
Gametophyte w/antheridia
Gametophyte
(prothallus)
Antheridia
sperm
Antheridia w/sperm
Antheridium
sperm
Gametophyte w/archegonia
Archegonia
Gametophyte w/archegonia 2
Archegonia
Archegonia on
surface of
prothallus
Fern sporangium and prothallus
Sporophyte
Gametophyte
(prothallus)
Fern Life Cycle
Seed producing plants
Gymnosperms
• Sporophyte dominant
• Conifers & relatives
• Heterosporous
Angiosperms
• Sporophyte dominant
• Flowering plants
• Heterosporous
– Mega- and micro– Small gametophye matures in
protected cones
– Mega- and micro– Small gametophye matures in
protected flowers
• Female in ovulate cones
• Male in staminate cones
• Female in flower ovary
• Male in flower anthers
– Wind blown-pollen
• Seeds protected in ovulate
cone
– Dispersed by wind, animal,
water sometimes
– Animal pollination and
some wind-blown
• Seeds protected in fruit
– Dispersed by animal mostly
Seed?
•
•
•
•
Ovule to seed
Ovule: sporophyte tissue surrounding sporangia
Seed coat: protective diploid tissue
Embryo: diploid zygote develops to sporophyte
Endosperm: nutritive tissue surrounding embryo to feed it
until it can photosynthesize on its own
Evolutionary importance of Seeds
• These plants produce pollen
– Pollen produces sperm nuclei (no water requrd)
• Expand over drier habitats
– Very protective over seasons (dormancy)
• Endosperm (embryonic food) – headstart
• Seed dispersal not dependent on water
– Collected and distributed further
• Flowering plants…even further in fruits
Pine lifecycle a
Pine lifecycle b
Pinus staminate cones
Pinus Ovulate cone (mature)
Staminate cone with pollen
Pollen grains
(microspores or
micorgametophytes)
Pinus microgametophytes
(mature pollen grains)
“Wing”
Tube nucleus
Generative
nucleus
Pinus ovulate cone
ovule
megasporophyll
Pinus megasporophyll
Megaspore
mother cell
Megasporophyll
Ovule w/megaspore mother cell
Megaspore
mother cell
Ovule
Pinus Megagametophyte
Ovule
Ovum
Pollen tubes
Pollen tube 2
Ovule
(megagametophyte)
Pinus seed
Haploid endosperm
(gametophyte tissue)
Cycadophyta (male)
Cycadophyta
Cycadophyta ovulate cones
Ginkgophyta
Ginkgophyta leaves
Ginkgo ovules/seeds
(naked)
ovules
(naked) seeds
Ginkgo staminate cones
Gnetophyta
Welwitschia mirabilis
• found in Angolan desert
• “desert onion”
Gnetophyta/Ephedra
Angiosperms /Anthophyta
•
•
•
•
Flowering Plants (anth = flower)
Seeds in a fruit (angio = container)
Double fertilization (see life cycle)
Like other pollen producers, is not
dependent on water for fertilization
What is a flower?
Flower structure
(corolla)
(carpel)
(calyx)
Plants:
• Monecious
– Has both sexes
• Dioecious
– Separate sexed plants
Flowers:
•
•
•
•
•
•
•
Perfect
Imperfect
Complete
Incomplete
Regular
Irregular
Inflorescences
Inflorescences
Anther1
Anther 2
Dehiscing anther
Pollen grains
Angiosperm lifecycle
Mature pollen grains
Lilium ovary (immature)
Lilium ovule
ovule
Megagametophyte
(embryo sac)
funiculus
A= plumule
B= hypocotyl
Dicot Seed
C = cotyledon
D = testa
E = radicle
E
Dicot seed germination
Radicle
Monocot seed
Embryo
Testa
Cotyledon
Endosperm
Plumule
Radicle
Monocot seed germination
Vascular tissue
• Transport water,
nutrients and food
between roots and
shoots
• System of xylem and
phloem cells
• Varied organization in
roots & shoots
Xylem cells – mature cells that become lignified
(thickened 2o cellulose), dies, and perforates from lysosomes
• Tracheids
– Primitive vascular plants
– Tapered, pits on ends, less
capillary action vs. vessel elements
• Vessel elements
–
–
–
–
Less primitive vascular plants
Pits on sides, open ends
Stacked to form long tubes
Advanced capillary action
• Transpiration
– Roots → shoots → leaves → out
– Via: root pressure and diffusion,
capillary pressure, negative pressure
of evaporation and cohesion
Phloem cells – living cells that transport sugars (sap)
• Sieve tubes
– no nucleus nor organelles
– Open sieve plates
• Companion cells
– Nucleated
– Adjoined to sieve tubes via
plasmodesmata
– Controls sieve tubes; regulates
movement
• Translocation
– Movement of sugars; sources to
sinks
leaves → roots, fruits, &/or
meristems
Plant Structure
• Apical meristem
– Mitotic division
– Stem & root tips
– Primary growth (length)
• Ground meristem
– Mitotic division
– Ground tissues:
• Parenchyma – large; storage
• Collenchyma – smaller;
flexible support
• Schlerenchyma – lignified;
rigid support; woody
• Cambium
– Mitotic secondary growth
– e.g. Vascular cambium
– e.g. Cork cambium
Leaf bud
Ground
meristem
Leaf bud 2
Apical meristem
Ground
meristem
Provascular
tissue
Monocot root
• Vascular bundles centered in
roots
• Cortex = outer layer
• Pith = center tissue
• Stele = pith + vascular tissue
Dicot root
Monocot root 2
Parenchyma
Pith
(Parenchyma)
Monocot root 3
Endodermis
Dicot root 2
Parenchyma
Dicot root 3
Endodermis and casparian strip
Pericycle
Phloem
Xylem
Vascular cambium
• Vascular bundles
– Xylem, phloem, and
cambium in between
– Scattered throughout
monocot stems
– Organized around
periphery of dicots
• Cambium
– Mitotic secondary
growth
– e.g. Vascular cambium
– e.g. Cork cambium
Monocot stem
Monocot stem 2
Sclerenchyma
Outside
Phloem
Sieve element
Companion cell
Xylem vessel
Air space
Inside
Dicot stem
Dicot stem 2
phloem
sclerenchyma
Vascular cambium
Woody stem
Summerwood
Springwood
Woody stem 2
Cork
Vascular cambium
Phloem
Phloem ray
Xylem
Woody stem 3
Cork (collenchyma
tissue)
Vascular cambium
Fruit – ripened ovary that protects the seeds
• Ripened?
• Layers of the ovary = Pericarp
– Exocarp
• Outer layer /ovarian wall
– Mesocarp
• Middle layer
– Endocarp
• Inner/adjacent to ovules
Fleshy fruits
• One or more ovarian layer is fleshy
– Drupe
• Endocarp is hardened; pit or stone
• Peaches, nectarines, apricots, etc
– Berry
• All or most pericarp is fleshy
• Grape, tomato, etc
– Pepo
• Berry with hard thick rind
• Melons, pumpkins, etc
– Hesperidium
• Berry with leathery rind
• Citrus
– Pome
• Swollen receptacle around ovary or
core
• Apple, pear
Dry fruits
• Lacks fleshy tissue
– Dehiscent fruits
• Split along a seam to
disperse seeds
• Legumes – two seams
• Capsules – multiple
seams
• Bean, pea pods,
peanuts, etc
– Indehiscent
• Do not split on a seam
• Achenes, grains, nuts
• Corn, wheat, etc
• Simple fruits
– Single ovary of one
flower
• Aggregate fruits
– Many ovaries of
one flower
• Multiple fruits
– Many ovaries of
many clustered
flowers
(inflorescence)
• Accessory fruits
– Tissue other than
ovary ripens
(swollen)
What is a coconut?
Fleshy? Dry? Other?
Drupe: a single fleshy fruit with a hard stone which contains the single seed
Plant Hormones (Ch. 39)
chemical communication and regulation
• Auxins
– Cell elongation
– Apical dominance
– Abscission suppression
• Slows the shedding of
leaves, flowers, fruits
– Fruit maturation
– Geotropism
• Phototropism
• Gravitropism
A. The tips have been removed. No auxin is
produced and the shoots do not grow longer.
B.
The tips have been covered so light cannot
reach them. Auxin is in the same
concentration on both sides of the shoots, so
they grow longer evenly on both sides.
C. One side of the tips are in more light than the
other side. Auxin is in a greater concentration
on the shaded side, causing the cells there to
grow longer than the cells on the light side.
Plant Hormones (Ch. 39)
chemical communication and regulation
• Giberellins
– GA or Giberellic acid
– Growth
• Release some buds and
seeds from dormancy
• Dwarf plants lack GA
– Spray on grapes =
bigger grapes
• Stem elongation
– Spray on dwarf plants
= taller plants
• Related to flowering in
some plants
Sold as common bio-fertilizer
Plant Hormones (Ch. 39)
chemical communication and regulation
• Cytokinins
– Cell division
– Stimulate bud growth
– Stimulates fruit &
embryo development
– Prevents leaf
senescence
• Slows aging to decay
With & without
Plant Hormones (Ch. 39)
chemical communication and regulation
• Abscisic Acid
– General growth
inhibitor
– Induces dormancy
• Wintering of buds
and leaves
– Closure of stomata
• Ethylene
– Gaseous hormone
– Plays role in fruit
ripening
– Fruit abscission
• (shedding)
– One of the reasons why
ripe bananas will
“ripen” other fruits