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 All stamens called androecium Male reproductive structures Anther Filaments All stamens called androecium

Flower Fertile parts Carpel All carpels called the gynoecium 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 Staminate flower; anthers only

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 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

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 Also known as solitary 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 Bluebonnet (Lupinus texensis)

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

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