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