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 modified sterile “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 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

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

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

Violet flower types