Flowers

Georgia O’Keefe – ‘Two Calla Lilies on Pink’

Tulips

Semper Augustus Tulip

Current Broken Tulip

Queen of the Night Tulip

Wild Rose

Yellow rose – many “petals” are actually modifiedsterile “petalloid” stamens

Helleborus – five separate carpels

Malus – crab apple – typical flower structure

Carpels may be fused together

Flower Shapes

• regular/ radially symmetrical/actinmorphic – many possible mirror images

• irregular/bilaterally symmetrical /zygomorphic - only one mirror image - peas, mints, orchids

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

Switchgrass inflorescence – a panicle

Blazing star – a spike

Wild parsnip – umbel inflorescence

Sunflower – Composite head

inflorescence

Birch - Catkins

Skunk cabbage inflorescence – with spathe and spadix

Borage Inflorescence – a scorpiod cyme

Poppy Flower - Solitary

Pollination syndromesamong 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

Honeybeepollinatingbeebalm –

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 flypollinatinga 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 – Avena fatua

Wild oat flower – close up

Cottonwood Catkins

Male Female