flowers and fruit. flower structure generalized flowers - 2 outer sets of sterile parts, 2 inner...

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

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

Carpels and Ovaries

• Flowering plants always have enclosed ovary wrapped in a carpel - nonflowering plants don't - this is the vessel of the angiosperm

• 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 pollinatedFemale 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

Umbel

Wild parsnip Queen Anne’s Lace

Sunflower – Composite headinflorescence

Catkin

Alder catkin

Scorpoid Cyme

Onosmodium

Skunk cabbage inflorescence – a spathe and spadix

Pollination syndromesamong the phloxes

Magnolia – beetle pollinated

Honeybee covered withpollen

Scotch broom – bee pollinated

Honeybeepollinatingbeebalm –Monarda sp.

With visible light with UV light

Nectar guides for honeybees

Cyrtid flypollinatinga composite

Caralluma – carrion fly pollinated

Erysimum – butterfly pollinated

Episcia – 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

• The pericarp may become dry and these form dry fruits

• The pericarp may also become soft, thick and fleshy – and these form fleshy fruits

Apples and Pears

Violetflowertypes