Bot 155 - Topic 2 - Flowers, Infloresences, Fruit and Pollin

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Transcript Bot 155 - Topic 2 - Flowers, Infloresences, Fruit and Pollin

corolla
calyx
Parts of a Flower
Floral Symmetry
Actinomorphic
Zygomorphic
Inferior
Half-Inferior
Superior
• Complete Flower -has pistil, stamens, petals and sepals
• Incomplete Flower –if any one of these parts is missing
The stamen and pistil are the essential parts of a
flower and are involved in seed production
• Perfect Flower - has pistil, stamens – may lack petals
and sepals
• Imperfect Flower - either pistil or stamen absents
Inflorescence Types
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Spike - an elongate, unbranched, indeterminate inflorescence with sessile
flowers.
Spikelet - a small spike, characteristic of grasses and sedges.
Raceme - an elongate, unbranched, indeterminate inflorescence with
pedicelled flowers.
Panicle - a branched raceme.
Corymb - a flat-topped raceme with elongate pedicels reaching the same
level.
Compound Corymb - a branched corymb.
Umbel - a flat-topped or rounded inflorescence with the pedicels originating
from a common point. Umbels can be determinate or indeterminate.
Compound Umbel - a branched umbel, with primary rays arising from a
common point, and secondary umbels arising from the tip of the primary
rays.
Capitulum - (or head)a dense vertically compressed inflorescence with
sessile flowers on a receptacle and subtended by an involucre of phyllaries,
characteristic of the Asteraceae. Heads can be determinate or indeterminate.
Thyrse - a many-flowered inflorescence with an indeterminate central axis
and many opposite, lateral dichasia; a mixed inflorescence, with determinate
and indeterminate shoots.
Inflorescence Types
• Simple Cyme or Dichasium - a determinate
inflorescence with 2 dichotomous lateral branches and
pedicles of equal length.
• Compound Dichasium - a branched dichasium.
• Compound Cymea - determinate thyrse.
• Helicoid Cyme (or bostryx) - a determinate cyme in
which the branches develop only on 1 side, due to the
abortion of opposing paired bud, the inflorescence thus
appearing simple.
• Cincinnus - a tight, modified helicoid cyme in which the
pedicels are very short.
• Scorpioid Cyme (or rhipidium) - a zig-zag determinate
cyme with branches developing alternately on opposite
sides of the rachis, due to abortion of opposing paired
bud.
Flowers are the Reproductive
Structures of the Angiosperms
Pollination
Fertilization
Pollination Syndromes
Pollination Syndromes in Modern
Flowers
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Beetle
Carrion Fly
Bee
Butterfly/Moth
Bat
Bird
• Wind
Beetles: Beetle-pollinated flowers are
usually flat or shaped like a shallow bowl
(easily accessible). The anthers and stigma
are exposed. The pollen or nectar is easily
accessible. The flowers have a dull greenish
or off-white color and a strong fruity or putrid
odor.
Beetle Pollination
Carrion and Dung Flies: The anthers and
stigma are hidden. The flowers lack nectar;
have a dull greenish, brownish, or purplish
color; and have a strong odor of decaying
protein. (Note that other flies visit different
types of flowers, and several fly families
actually mimic bees.)
Fly Pollination
Bees: Bee-pollinated flowers usually have
an intricate shape, and strength and
dexterity are often required to enter. The
anthers and stigma are usually hidden. The
flowers produce moderate amounts of
nectar that is hidden (but there may be
patterned nectar guides, visible in either
ambient or ultraviolet light). The flowers are
blue, violet, or yellow, with a weak but
pleasant odor.
Butterflies and Moths: Butterfly and mothpollinated flowers are often tubular or funnelshaped, with nectar at the base. The length
of the tube may be correlated with the length
of the arthropods proboscis. The flower often
has some sort of landing platform. Butterfly
flowers can be yellow, blue, violet, or red
and often lack a strong odor. Moth flowers
are nocturnal, often with a white or drab
color and a sweet scent.
Bats: Bat-pollinated flowers are nocturnal.
They have an easily accessible position
away from the leaves or may appear before
the leaves develop. The flowers may be
either large and cup-shaped or "brushlike,"
with many exposed stamens. They produce
large amounts of both pollen and nectar, and
they have a dull color and a strong,
sometimes unpleasant odor.
Hummingbirds: Hummingbird-pollinated
flowers are tubular, and the length of the
tube may be precisely correlated with the
length of the pollinator bill. They produce
large amounts of nectar available at the
base of the tube, have a red color, and lack
an odor.
Wind: Wind-pollinated flowers often appear
before the leaves develop. The flowers are
exposed, reduced, and inconspicuous. The
anthers and stigmas are exposed. The
anthers often dangle from their filaments
and produce large amounts of pollen; the
stigmas are often long and feathery; the
flowers lack an odor.
Pollination
Fertilization
A fruit
develops
from the
ovary wall
after
fertilization
of the egg
in the ovule
A seed
develops
from the
ovule after
fertilization
of the egg
in the ovule
Simple Fruit
Simple fruit
Pea - Legume
pericarp
Maple - Samara
pericarp
seed inside
Nectarine - Drupe
Pericarp
Exocarp
Mesocarp
Endocarp
Pumpkin - Pepo
Blackberry
Blackberry
Multiple Fruit
Multiple Fruit
Mullberry
Pineapple
Pineapple
Osage orange
Simple Accessory Fruit
Apple - Pome
Aggregate Accessory Fruit