Flowers
Tulips
Semper Augustus Tulip
Current Broken Tulip
Queen of the Night Tulip
Wild Rose
Yellow rose – many “petals” are actually modified
sterile “petalloid” stamens
Helleborus – five separate carpels
Malus – crab apple – typical flower structure
Flower Shapes
• regular/ radially symmetrical/actinmorphic mirror images
• irregular/bilaterally symmetrical
/zygomorphic - only one mirror image peas, mints
Flower Shapes
Regular/Actinomorphic
Irregular/Zygomorphic
Flower Sexuality, etc.
• monoecious - separate flowers for male and female both on
one plant – corn
• dioecious - male and female plants are separate - separate
sexes - gingko
• Perfect flower - flower has stamens and carpels – bisexual
flowers
• Imperfect flower - lacks either stamens or carpels - will be
staminate or carpellate (pistillate)
• Complete - has sepals, petals, stamens and carpels
• Incomplete - lacking one of the 4 main flower parts
Jatropha – monoecious but insect pollinated
Willows - Dioecious
Complete Flower
Incomplete Flower – Panic Grass
Inflorescence
• Often flowers, especially small flowers, are
gathered into a structure known as an
inflorescence – an aggregation of flowers
on a single flowering branch
• Bract - more or less modified leaf that
subtends flower or inflorescence- bract can
look like normal leaf
• Bract can also look like petal - petaloid
Dogwood with petalloid leafy bracts
Types of Inflorescence
1. Racemous or indeterminant - youngest
flower at apex - in theory could produce
flowers forever - some may by fruiting
while apex still flowering - include racemes, panicle, spike, corymb, head,
umbel, catkin
2. Cymose or determinant - oldest flowers at
apex - moving down younger flowers cyme, scorpiod cyme
Larkspur inflorescence – a
raceme
Wild parsnip – umbel
inflorescence
Sunflower –
Composite head
inflorescence
Borage Inflorescence – A
scorpiod cyme
Skunk cabbage inflorescence –
with spathe and spadix
Pollination syndromes
among the phloxes
Beetle Pollination
• Several modern plant species are pollinated largely or
exclusively by beetles - beetles were probably the first
important group of insect pollinators
• Beetle flowers - large, borne singly - Magnolia, some
lilies, California poppies, and wild roses
• or small and in inflorescence - dogwood, elders, parsley
• Beetles have quite a well-developed sense of smell and
their flowers are often quite odoriferous - fruity, spicy or
foul odors such as from fermentation
• Flowers often white or dully colored
• Often produce large amounts of pollen, some produce a
little nectar, beetles chew directly on petals of some
Magnolia – beetle pollinated
Bee and Wasp Pollination
• Most important group of flower pollinators
• Bees and wasps have mouthparts, body hairs and other
appendages that allow them to efficiently collect and carry
pollen and nectar
• 20,000 species of bees - most pollinate flowers
• Bees highly visual - don’t see red, but do see ultraviolet as a
color
• Bee flowers - typically have showy, brightly colored petals,
often blue or yellow - never pure red
• Have patterns called nectar guides which direct bees to pollen
and nectar - often in UV color
• Nectaries usually at base of corolla tube, produce large amounts
of nectar, concentrated nectar - up to 70% sugar
• Petals often have landing platform for bees
Honeybee
covered with
pollen
Scotch broom – bee pollinated
Honeybee
pollinating
beebalm –
Monarda sp.
With visible light
with UV light
Nectar guides for honeybees
Fly Pollination
• can flower during day or night
• color highly variable, but will be purple-brown or
greenish for carrion and dung flies
• often very strong odors – smelling of decay for
carrion flies
• usually fairly open flowers, but some have deep
traps to keep flies inside for a night
• usually no reward but some provide pollen or
nectar
Cyrtid fly
pollinating
a composite
Caralluma – carrion fly pollinated
Butterfly and Moth Pollination
• Butterfly and moth flowers similar to bee flowers because
moths and butterflies also guided to flowers by
combination of sight and smell
• Some butterflies can see red, so often have red or orange
color for flower
• Nectary is often at bottom of long, slender corolla tube or a
nectar spur - only accessible to long sucking probocis of
moths and butterflies
• Nectar is copious, but not so concentrated - often 25%
sugar
• Moths are nocturnal so many of their flowers emit heavy
fragrance at night, often pale or white in color - scent is
sweet and penetrating
Erysimum – butterfly pollinated
Episcia – moth pollinated
Bird Pollination
• Bird pollinated flowers produce copious, thin nectar - often
about 25% sugar, often very high in sucrose - may actually
drip with nectar
• Usually have little odor because birds have poor sense of
smell
• Birds see red and bird pollinated flowers often very
colorful with reds and yellows - red columbine, fuchsia,
passion flower, hibicus, poinsettia, many cactus and
orchids
• The flowers are usually large or part of large inflorescence
• Nectar usually held in long tubes that other animals can’t
reach
Hummingbird pollination
Ipomopsis aggregata – hummingbird pollinated
Greater double-collared sunbird
Proteus – pollinated by perching birds
Bat Pollination
• About 250 species of bat (25%) include some pollen,
nectar or fruit in their diet - many pollinate flowers as part
of their feeding
• Bat flowers are similar to bird flowers - large, strong
flower which produces copious nectar - Often dull colored
because open at night - may only open at night
• Often have very strong fermenting or fruitlike odors, may
be musky odors too
• Bat flowers often hang down below foliage to enable bats
to easily get to the flower
• Banana, mango, sisal and kapok flowers pollinated by bats
Bat pollination
Wind Pollination
• Usually have dull colors, relatively odorless, do not produce nectar,
petals small or absent, sexes often separated
• Wind pollinated flowers are most common in temperate areas where
large stands of single species of plant occur
• With trees, wind pollination occurs in spring before leaves have
emerged - usually have well exposed stamens to shed pollen to wind
and stigma also exposed - often with feathery outgrowths to catch
pollen
• Often the plants have various mechanisms to promote out-crossing separate sexes - dioecious - willows, poplars
• unisexual flowers on same tree - monoecious - oaks, birches
• Self-incompatible - grasses
• Flowers are typically small, have single ovule per flower - however
have many flowers borne in inflorescences and multiple inflorescences
Box elder – wind pollinated – female left, male right
Wild oats –
Whole plant
Wild oat flower – close up
Cottonwood Catkins
Male
Female