Flowers and Fruit
Flower Structure
• Generalized flowers - 2 outer sets of sterile parts, 2 inner sets of fertile
parts
• Outer sterile part - sepals, collectively the calyx - may do
photosynthesis, protect flower, usually like leaves in texture, protect
bud - form outer covering of bud
• Next sterile part - petals - not like leaves in texture, usually not green,
collectively called corolla - petalloid - petal like in appearance
• Both sepals and petals can be fused - so sepals joined together, petals
joined together
• Perianth - calyx and corolla together - used when the two cannot be
distinguished - sometimes sepals and petals are called tepals for
perianth if very similar in appearance – like in Tulips
• If only one set of sterile parts, they are always called sepals; sometimes
whole perianth is missing
• First fertile parts - stamens - male – androecium - Can be sterile and
modified to look like petals
• Innermost fertile parts - pistils, female - gynoecium
Wild Rose
Yellow rose – many “petals” are actually modified
sterile “petalloid” stamens
Carpels and Ovaries
• Flowering plants always have enclosed ovary
wrapped in a carpel - nonflowering plants don't
• Carpel is highly modified leaf - a simple pistil is
one ovary
• Pistil may be made up of one carpel or several
fused carpels
• Often the bottom part called the ovary, with
stigma at top to receive pollen, style connects
them - fused carpels may have separate style and
stigma or they may all be fused
Helleborus – five separate carpels
Malus – crab apple – typical flower structure
Plant Sexuality
• 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
Complete and Incomplete Flowers
Jatropha – monoecious but insect pollinated
Female left, male right
Dioecious - Holly
Female flower
Male flower
Berries on female
Inflorescence terms
• 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
flower groups - bract can look like normal leaf
• bract can also look like petal - petalous - dogwoods have
big white "petals" that are really petaloid bracts
• peduncle - stalk of cluster of flowers
• pedicel - stalk of individual flower
• petiole - leaf stalk
Dogwood with petalloid leafy bracts
Types of Inflorescence
1. 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. determinant - oldest flowers at apex moving down younger flowers - cyme,
scorpiod cyme
Raceme
Larkspur
Panicle
Panicum - switchgrass
Spike – prairie blazing star
Corymb
Yarrow
Umbel
Wild parsnip
Queen Anne’s Lace
Sunflower –
Composite head
inflorescence
Catkin
Alder catkin
Scorpoid Cyme
Onosmodium
Skunk cabbage inflorescence – a spathe and spadix
Pollination syndromes
among the phloxes
Magnolia – beetle pollinated
Honeybee
covered with
pollen
Scotch broom – bee pollinated
Honeybee
pollinating
beebalm –
Monarda sp.
With visible light
with UV light
Nectar guides for honeybees
Cyrtid fly
pollinating
a composite
Stapelia gigantea – carrion fly pollinated
Monarch butterfly pollinating milkweed
Brugmansia – moth pollinated
Hummingbird pollination
Ipomopsis aggregata – hummingbird pollinated
Greater double-collared sunbird
Proteus – pollinated by perching birds
Bat Pollination
Box elder – wind pollinated – female left, male right
Wild oats –
Whole plant
Wild oat flower – close up
Fruit Types
• A fruit may be defined as a matured ovary
• There are two basic fruit types – dry or
fleshy. These types arise from the
development of the pericarp – outer cover
of ovary
• The pericarp may become dry and these
form dry fruits
• The pericarp may also become soft, thick
and fleshy – and these form fleshy fruits
Pome - Apples and Pears
Violet
flower
types