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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 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 flattopped 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 flattopped 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 BREAK
