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