Flowers, Inflorescences & Fruits

• Floral characteristics are the most commonly features to identify plants

• Much more reliable than vegetative characteristics

Flowers, Inflorescence & Fruits

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

• 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

Flower

Presence or Absence of PartsTerms Applied to Individual Flowers

• Complete: has all the floral parts– Sepals– Petals– Stamens– Carpels

• Incomplete: missing one of more of the floral parts

Presence or Absence of PartsTerms Applied to Individual Flowers

Ginger flower missing petals

• Perfect (=bisexual): flower with both stamens and carpels

Presence or Absence of PartsTerms Applied to Individual Flowers

Grape flower with stamens and carpels

Presence or Absence of PartsTerms Applied to Individual Flowers

• Imperfect (=unisexual): missing stamens or carpels, but not both

Staminate flower; anthers only

• Staminate (=male): unisexual flower with just stamens present

Presence or Absence of PartsTerms Applied to Individual Flowers

Imperfect staminate flower; stamens only, no carples

• Carpellate (=female): unisexual flower just carpels present

Presence or Absence of PartsTerms Applied to Individual Flowers

Imperfect carpellate flower; carpel only; no stamens

• Monoecious: any plant that has both staminate and carpellate flowers

Presence or Absence of PartsTerms Applied to Plants with Imperfect Flowers

• Dioecious: plant that has either staminate flowers or carpellate flowers, but not both

Presence or Absence of PartsTerms Applied to Plants with Imperfect Flowers

• 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 to all the other floral parts

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 to all the other floral parts

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 to all the other floral parts

Insertion of Floral Parts

Floral Symmetry

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

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

Floral Symmetry

Inflorescence Types

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

• Inflorescence type determined by:– Number of flowers– Positional relationships– Degree of the

development of their pedicels

– Nature of their branching pattern

Inflorescence Types

• Terminal: flower at the tip of a stem– Also known as solitary

Simple Inflorescences

Scarlet rose-mallow (Hibiscus coccineus)

Compound Inflorescences

• Two or more flowers per inflorescence

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

Compound Inflorescences

Spiked blazing star (Liatris spicata)

• 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

Bluebonnet (Lupinus texensis)

• 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

Compound Inflorescences

Butterfly weed (Asclepias sp.)

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

Compound Inflorescences

• Panicle: a much-branched inflorescence with a central rachis which bears branches which are themselves branched

Compound Inflorescences

BREAK