Flowers Inflorescences and Fruits

Flowers, Inflorescences & Fruits

Flowers, Inflorescence & Fruits • Floral characteristics are the most commonly features to identify plants • Much more reliable than vegetative characteristics

Flower • A typical flower is a stem tip bearing two whorls of appendages that are sterile and two that are fertile • All four whorls are considered to be modified leaves

Flower • Typical flower – 4 main parts

Flower • Sterile parts – Sepals: protect flower bud • All sepals called calyx

– Petals: pretty parts that attract pollinators • All petals called corolla

– Calyx and corolla make up the perianth

Flower • Fertile parts – Stamens • Male reproductive structures – Anther – Filaments

– All stamens called androecium

Flower • Fertile parts – Carpel • Stigma • Style • Ovary

– All carpels called the gynoecium

Presence or Absence of Parts Terms Applied to Individual Flowers • Complete: has all the floral parts – – – –

Sepals Petals Stamens Carpels

Presence or Absence of Parts Terms Applied to Individual Flowers • Incomplete: missing one of more of the floral parts

Ginger flower missing petals

Presence or Absence of Parts Terms Applied to Individual Flowers • Perfect (=bisexual): flower with both stamens and carpels

Grape flower with stamens and carpels

Presence or Absence of Parts Terms Applied to Individual Flowers • Imperfect (=unisexual): missing stamens or carpels, but not both

Presence or Absence of Parts Terms Applied to Individual Flowers • Staminate (=male): unisexual flower with just stamens present

Imperfect staminate flower; stamens only, no carples

Presence or Absence of Parts Terms Applied to Individual Flowers • Carpellate (=female): unisexual flower just carpels present

Imperfect carpellate flower; carpel only; no stamens

Presence or Absence of Parts Terms Applied to Plants with Imperfect Flowers • Monoecious: any plant that has both staminate and carpellate flowers

Presence or Absence of Parts Terms Applied to Plants with Imperfect Flowers • Dioecious: plant that has either staminate flowers or carpellate flowers, but not both

Insertion of Floral Parts • The position of the gynoecium in relation to all the other floral parts is the basis for for the terminology used in keys and taxonomic descriptions

Insertion of Floral Parts • Hypogynous: the sepals, petals, and stamens are inserted under the carpel – Ovary is said to be superior

Insertion of Floral Parts • In a perigynous flower, the sepal, petals, and stamens are fused together to form a cup called the hypanthium – The gynoecium sits inside the cup but is not fused to it – Ovary is said to be superior

Insertion of Floral Parts • In a epigynousflower, the sepals, petals, and stamens arise from a point above the ovary – Ovary is said to be inferior

Floral Symmetry • Actinomorphic (=radial): cutting the flower in any pane produces a mirror image

Floral Symmetry • Zygomorphic (=bilateral): can cut the flower in only one plane to get a mirror image

Inflorescence Types • An inflorescence is an arrangement of one or more flowers on a floral axis

Inflorescence Types • Inflorescence type determined by: – Number of flowers – Positional relationships – Degree of the development of their pedicels – Nature of their branching pattern

Simple Inflorescences • Terminal: flower at the tip of a stem

Scarlet rose-mallow (Hibiscus coccineus)

Compound Inflorescences • Two or more flowers per inflorescence

Compound Inflorescences • Spike: elongate inflorescence; flowers are sessile, dense, or remote from one another

Spiked blazing star (Liatris spicata)

Compound Inflorescences • Catkin: a pendant or erect inflorescence in which unisexual flowers lack petals and are hidden by scaly bracts

Compound Inflorescences • Raceme: an elongate inflorescence of pedicellate flowers on an unbranched rachis

Compound Inflorescences • Umbel: a flat-topped or somewhat rounded inflorescence in which all of the pedicels arise from a common point at the tip of the peduncle

Butterfly weed (Asclepias sp.)

Compound Inflorescences • Corymb: a flat-topped or somewhat rounded inflorescence in which the pedicels of varying length are inserted along the rachis

Compound Inflorescences • Panicle: a muchbranched inflorescence with a central rachis which bears branches which are themselves branched

Fruits • Ripened or mature ovary • Contains seeds

Fruit Types • Dry fruits – Indehiscent – Dehiscent

• Fleshy fruits – True fruits – False fruits

Fruit Types Dry, Indehiscent • Achene

Sunflower (Helianthus sp.)

Fruit Types Dry, Indehiscent

• Caryopsis (=grain)

Fruit Types Dry, Indehiscent • Samara

Maple (Acer sp.)

Fruit Types Dry, Indehiscent • Schizocarp

Fruit Types Dry, Dehiscent • Capsule

Mexican buckeye (Ungnadia speciosa)

Fruit Types Dry, Dehiscent • Silique

Fruit Types Dry, Dehiscent • Legume

Fruit Types Dry, Dehiscent • Loment

Fruit Types Dry, Dehiscent • Follicle

Fleshy Fruits True Fruits • Derived from a gynoecium of a single flower

Fleshy Fruits True Fruits • Drupe

Fleshy Fruits True Fruits • Berry

Fleshy Fruits True Fruits • Pepo

Stink gourd (Cucurbita foetidissima)

Fleshy Fruits True Fruits • Pome

Fleshy Fruits True Fruits • Hesperidium

Fleshy Fruits False Fruits • Fruit derived from parts other than the gynoecium

Fleshy Fruits False Fruits • Accessory: fruit from the receptacle

Fleshy Fruits False Fruits • Aggregate: fruit formed from many separate flowers

Magnolia (Magnolia sp.)

Fleshy Fruits False Fruits • Multiple: fruits formed by the fusion of an entire inflorescence

Fleshy Fruits False Fruits • Syconium: a hollow, vase-like inflorescence with the flowers lining the inside

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