Download basic horticulture – notes

BASIC HORTICULTURE – NOTES
WEEK #8
FLOWERS and FRUITS
EXAM #2 – Give exam
HAND BACK LAB SHEETS – ASSIGNMENTS
 MICROSCOPE COMPETENCY – AM only
FLOWERS (Look at overhead on Magnoliaphyta)
 Magnoliopsida – DICOTS
 Liliopsida – MONOCOTS
FUNCTIONS OF FLOWERS
 SEXUAL REPRODUCTION
o 20-50% of plants ENERGY goes into sexual
reproduction, this is a VERY IMPORTANT
ACTIVITY
o Uniting of MALE and FEMALE GAMETES to create
OFFSPRING DIFFERENT than BOTH PARENTS
 Mixing GENES creates GENETIC DIVERSITY
 GREATER GENETIC DIVERSITY =
GREATER CHANCE that offspring will have
BETTER ABILITY to SURVIVE
 ABILITY to SURVIVE depends on potentially
GREATER ADAPTIBILITY to the
ENVIRONMENT
 To AID SEXUAL REPRODUCTION flowers have
ADAPTED to do TWO things well:
o ATTRACT POLLINATORS (insects and birds) to
insure success in POLLINATION and hopefully
FERTILIZATION
o PRODUCE FRUIT to PROTECT SEED and insure
SEED DISPERSAL
PARTS of a FLOWER – MORPHOLOGY (Show overhead)
 4 – PARTS
o ACCESSORY PARTS
 SEPALS
 PETALS
o ESSENTIAL PARTS for reproduction
 STAMENS
 PISTIL(S)
 SEPALS – Outermost layer of the flower
o Normally GREEN and LEAFY
o Enclose bud for PROTECTION
o All together called CALYX
 PETALS – Next layer inside sepals
o Usually COLORED
o To ATTRACT POLLINATORS
o Collectively called the COROLLA
 MONOCOTS – 3’s, DICOTS – 4’s and 5’s
 REGULAR – radial symmetry
Example: Cosmos, Fuchsia
 IRREGULAR – bilateral symmetry
Example: Pansy, Orchid, African violet
 PERIANTH – SEPALS and PETALS together
o TEPALS – petals and sepals SAME SIZE and SHAPE
Example: Tulips, Lilies
 STAMENS – MALE part of the flower
o FILAMENT – STALK holding up the anther
o ANTHER – produces the POLLEN
o POLLEN – GRAINS containing the MALE
GAMETES or GAMETOPHYTE
 PISTIL – FEMALE part of the flower
o STIGMA – sticky landing platform for POLLEN
o STYLE – stalk that holds up STIGMA
o OVARY – base that encloses the OVULES
o OVULES – contains unfertilized EGGS or FEMALE
GAMETES or GAMETOPHYTE
o CARPELS – Divisions of the Pistil into CHAMBERS
FLOWER TERMS
 COMPLETE – contains ALL 4 PARTS
 INCOMPLETE – less than all 4 PARTS
 PERFECT – have the ESSENTIAL parts
o STAMENS and PISTIL
 IMPERFECT – lacking the ESSENTIAL parts
o STAMINATE flowers have STAMENS
o PISTILLATE flowers have PISTIL(S)
 MONOECIOUS (“one house”)
o STAMINATE and PISTILLATE flowers on the SAME
plant (MALE and FEMALE flowers)
Example: Birch, Corn, Squash
 DIOECIOUS (“two houses”)
o STAMINATE and PISTILLATE flowers on
SEPARATE plants (MALE and FEMALE plants)
Example: Kiwi, Holly, Skimmia
FLOWER ARRANGEMENT - INFLORESCENCES
 Flowers can occur SINGLY as in a Tulip, or in CLUSTERS
of FLOWERS or FLORETS, we call these arrangements
INFLORESCENCES
 INFLORESCENCE STRUCTURE
o RECEPTACLE – stem tip bearing flower parts
o PEDICEL (PEDICLE)– stalk for single flower or floret
o PEDUNCLE – main stalk for inflorescence
 TYPES of INFLORESCENCES
o INDETERMINATE – florets open from BOTTOM UP
or OUTSIDE IN
 Length of stalk is INDETERMINATE because
stalk continues to GROW as florets open
o DETERMINATE – florets open from the TOP DOWN
 LENGTH of stalk is DETERMINED by the first
flower OPENING at top
o INDETERMINATE TYPES
 SPIKE – florets attached directly to stalk
 SPADIX – male flowers at top of spike, female at
bottom
 CATKIN – spike with male or female flowers
only
 RACEME – spike with pedicels or small stalks
attaching to peduncle
 PANICLE – branched raceme
 CORYMB – unevenly elongated pedicels to form
flat top
 UMBEL – equal length pedicels attached at one
point to form flat top
 COMPOUND UMBEL – branched umbel
 HEAD – florets on disc
 RAY and DISC flowers
o DETERMINATE
 SOLITARY – one flower on stalk
 CYME – like a raceme but flowering from top
down
 COMPOUND CYME – branched cyme
POLLINATION (Show model)
 POLLINATION – TRANSFER of POLLEN from ANTHER
to STIGMA
o SELF-POLLINATION – within the SAME FLOWER
or PLANT
o CROSS-POLLINATION – between two DIFFERENT
PLANTS
 Cross-pollination is PREFERRED, because it
creates more POSSIBILITY for GENETIC
DIVERSITY
Example: HYBRIDIZING is the deliberate
CROSS-POLLINATION of plants to produce
SUPERIOR TRAITS
 Plants ASSURE CROSS-POLLINATION by
 SELF INCOMPATIBILITY
 STIGMA doesn’t allow it’s own pollen
to fertilize egg
o RECOGNIZES pollen SHAPE
o Or CHEMICALLY
INCOMPATIBLE
 Generally it must be SAME SPECIES
but a different plant to CROSS
Example: Kale will not self pollinate
 SPATIAL SEPARATION of anthers and
stigma
 STAGGERED TIMING – of pollen release
and stigma RECEPTABILITY
 SELF- POLLINATION as last resort
 Flower brushes stigma against anther
Example: Foxglove
ATTRACTING POLLINATORS – INSECTS and BIRDS
 SOME FLOWERS are so REDUCED that they don’t attract
pollinators because they are pollinated by WIND
o
o
o
o
o
o
10% of ANGIOSPERMS
INCONSPICUOUS flowers
produce lots of POLLEN
NOT the most EFFECTIVE use of energy
spreads offspring farther, GOOD for COMPETITION
promotes CROSS POLLINATION
Example: Grasses, Conifers, Some dicot trees – Beech,
Oak, Elms, Hazels
 Providing NECTAR and POLLEN as FOOD is the PAYOFF
for POLLINATORS
o A form of MUTUALISM or CO-EVOLUTION
 ATTRACTANTS
o COLOR – NECTAR GUIDES
 BEES – White, Yellow flowers (see UV light)
 HUMMINGBIRDS – Red flowers
 MOTHS – White, Pastel flowers (seen at night)
o SCENT
 BUTTERFLIES and MOTHS – sweet nectar
 FLIES – meat smell, odiferous
o SHAPE of FLOWER or INFLORESCENCE
 UMBELS or HEADS – small insects with short
proboscis (nose)
 IRREGULAR flowers – BEES and INSECTS
 LONG TUBULAR flowers with NECTARIES
at base - HUMMINGBIRDS
 CLUSTERS of flowers away from leaves –
BATS
FERTILIZATION (Show overhead)
 UNION of MALE GAMETE (sperm within pollen) with
FEMALE GAMETE (egg within ovule) to form a ZYGOTE
o POLLEN adheres to stigma and one nucleus (in TUBE
cell) GROWS POLLEN TUBE into style, ovary and
ovule (uses food and hormones of pistil to do this)
o SPERM nucleus (in GERM cell) DIVIDES to form 2
NUCLEI
 One UNITES with EGG in OVULE to form
ZYGOTE and eventually EMBRYO in seed
 One UNITES with 2 NUCLEI in OVULE to form
the ENDOSPERM as a FOOD SOURCE for the
developing EMBRYO
 EMBRYO + Endosperm + SEED COAT = SEED
 APOMIXIS
o Development of seeds WITHOUT FERTILIZATION
o Seeds IDENTICAL to parent (a CLONE)
Example: Corn
FRUITS
As an OVULE is FERTILIZED by POLLEN this starts growth and
transformation into a SEED
Developing EMBRYO produces HORMONES inside the SEED
that starts to develop the OVARY into a FRUIT
FUNCTIONS of FRUIT
 PROTECT RIPENING SEED
 DISPERSAL of SEED
o Important for SURVIVAL
o Less COMPETITION away from the PARENT plant
o SEED DISPERSAL METHODS
 WIND
 FINE SEED to blow
 WINGS to fly
Example: Dandelion, Maple, Orchids
o WATER
 FLOAT by trapping AIR in fruit structure, hard
seed coat
Example: Coconuts
o ANIMALS
 FOOD - eating and excreting, also adds nutrients
 BARBS to travel on animal fur or clothing
Example: Catchweed Bedstraw (weed)
 STICKY to travel on animals
Example: Mistletoe
o MECHANICAL
 Seeds PROPELLED away from plant
Example: Impatiens, Violets
CLASSIFICATION of FRUIT
 FRUIT - PERICARP STRUCTURE
o EXOCARP – outer layer of developing OVARY wall
o MESOCARP – middle part
o ENDOCARP – inside of OVARY
 FRUIT DEVELOPMENT (Show overhead)
o SIMPLE – one FLOWER with one PISTIL
o AGGREGATE – one FLOWER with many PISTILS
Example: Strawberry, Blackberry, Raspberry
o MULTIPLE – WHOLE INFLORESCENCE with
common PEDUNCLE fuses in to one FRUIT
Example: Mulberry, Pineapple, Fig
 TYPES of FRUITS
o SIMPLE – one FLOWER with one OVARY
 FLESHY – soft, fleshy, edible
 BERRY – soft throughout
 PEPO – berry with RIND
 HESPERIDIUM – berry with
LEATHERY RIND and juicy
segmented middle
 DRUPE – fleshy with stone
 POME – ovary and receptacle fused
o DRY when ripe
 INDEHISCENT – does not split open
 ACHENE – one seed, seed coat not fused to
seed
 SAMARA – winged achene
Example: Maple, Elm
 NUT – achene with hard wall
 SCHIZOCARP – 2 or more achenes
attached at one spot
Example: Carrot, Dill, Parley
 GRAIN – one seed with coat fused
 DEHISCENT – splits when ripe




FOLLICLE – splits along one side
LEGUME – splits on two sides
CAPSULE – splits along three or more sides
SILIQUE – splits along two sides with a
partition, longer than wide
 SILICLE – same as above, but as long as
wide
FLOWERING
CONTROL and TIMING of FLOWER production in plants is
important to SURVIVAL of the SPECIES in nature
It’s CRITICAL to FLOWER at roughly the SAME TIME for
POLLINATION, FERTILIZATION and FRUIT & SEED SET to
occur
 Especially for CROSS-POLLINATED plants
FACTORS affecting FLOWER GROWTH and DEVELOPMENT:
 MATURITY of the plant or RIPENESS to FLOWER
 PHOTOPERIODISM (response to length of daylight)
 VERNALIZATION (temperature response)
 THERMOPERIODISM
 MOISTURE AVAILABILITY during BUD SET
 MATURITY of the plant or RIPENESS to FLOWER
o FLOWERING and FRUIT SEED production requires
ENERGY
o NET PHOTOSYNTHETIC PRODUCTION must be
POSITIVE for GROWTH
o To achieve this the plant must have:
 Adequate LEAVES for photosynthesis for
vegetative and flower growth
 Adequate ROOTS for water and nutrient
absorption, and anchorage for support
 Adequate STEMS for strength to support heavy
flowers and fruit
o Plants which BLOOM PREMATURELY do not have
SUFFICIENT FOOD, WATER and NUTRIENTS, or
SUPPORT for FLOWERS to produce a LARGE
QUANTITY of SEEDS for SURVIVAL