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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
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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
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
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
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
Umbel Wild parsnip Queen Anne’s Lace
Sunflower – Composite head inflorescence
Catkin Alder catkin
Scorpoid Cyme Onosmodium
Pollination syndromes among the phloxes
Honeybee covered with pollen
Honeybee pollinating beebalm – Monarda sp.
With visible light with UV light Nectar guides for honeybees
Cyrtid fly pollinating a composite
Wild oats – Whole plant
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
Violet flower types
