flowers, inflorescences & fruits · flower •a typical flower is a stem tip bearing two whorls...
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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 Parts Terms 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 Parts Terms Applied to Individual Flowers
Ginger flower missing petals
• Perfect (=bisexual): flower with both stamens and carpels
Presence or Absence of Parts Terms Applied to Individual Flowers
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 (=male): unisexual flower with just stamens present
Presence or Absence of Parts Terms Applied to Individual Flowers
Imperfect staminate flower; stamens only, no carples
• Carpellate (=female): unisexual flower just carpels present
Presence or Absence of Parts Terms 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 Parts Terms Applied to Plants with Imperfect Flowers
• Dioecious: plant that has either staminate flowers or carpellate flowers, but not both
Presence or Absence of Parts Terms 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
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
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
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
• 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
• Ripened or mature ovary
• Contains seeds
Fruits
Fruit Types
• Dry fruits
– Indehiscent
– Dehiscent
• Fleshy fruits
– True fruits
– False fruits
• Achene
Fruit Types Dry, Indehiscent
Sunflower (Helianthus sp.)
• Caryopsis (=grain)
Fruit Types Dry, Indehiscent
• Samara
Fruit Types Dry, Indehiscent
Maple (Acer sp.)
• Schizocarp
Fruit Types Dry, Indehiscent
• Capsule
Fruit Types Dry, Dehiscent
Mexican buckeye (Ungnadia speciosa)
• Silique
Fruit Types Dry, Dehiscent
• Legume
Fruit Types Dry, Dehiscent
• Loment
Fruit Types Dry, Dehiscent
• Follicle
Fruit Types Dry, Dehiscent
Fleshy Fruits True Fruits
• Derived from a gynoecium of a single flower
• Drupe
Fleshy Fruits True Fruits
• Berry
Fleshy Fruits True Fruits
• Pepo
Fleshy Fruits True Fruits
Stink gourd (Cucurbita foetidissima)
• Pome
Fleshy Fruits True Fruits
• Hesperidium
Fleshy Fruits True 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
Fleshy Fruits False Fruits
Magnolia (Magnolia sp.)
• 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
Fleshy Fruits False Fruits
BREAK