FLOWERSFLOWERS

The sexual reproductive The sexual reproductive structures of structures of

angiospermsangiosperms

What is a flower?What is a flower?

• A A flowerflower is a highly modified shoot is a highly modified shoot bearing specialized appendages bearing specialized appendages (modified leaves).(modified leaves).

• AngiospermsAngiosperms are considered the are considered the flowering plants.flowering plants.

• Both Both monocotsmonocots (ie grasses) and (ie grasses) and dicotsdicots (ie petunias) flower. (ie petunias) flower.

PedicelPedicel

• The floral stalk is The floral stalk is referred to as the referred to as the pedicel.pedicel.

ReceptacleReceptacle

• The modified shoot The modified shoot (or floral axis) is (or floral axis) is called the called the receptacle.receptacle.

PerianthPerianth

• The perianth The perianth consists of the outer consists of the outer protective and/or protective and/or colorful structures. colorful structures. The perianth The perianth includes the sepals includes the sepals and petals, and petals, collectively known collectively known as the calyx (sepals) as the calyx (sepals) and corolla (petals).and corolla (petals).

Perianth PartsPerianth Parts

• If the sepals and petals are If the sepals and petals are distinctively different in appearance, distinctively different in appearance, they continue to be known as they continue to be known as sepalssepals

and and petalspetals..

• If sepals and petals are If sepals and petals are undifferentiated in appearance (ie undifferentiated in appearance (ie

many cactus flowers), they are many cactus flowers), they are collectively described as collectively described as tepalstepals..

AndroeciumAndroecium

• The androecium The androecium comprises all the comprises all the stamens of the stamens of the flower. Stamens are flower. Stamens are usually differentiated usually differentiated into an anther and a into an anther and a filament. Each filament. Each anther usually anther usually contains four pollen contains four pollen sacs. sacs.

Pollen SacsPollen Sacs

• Each anther usually contains four pollen Each anther usually contains four pollen sacs, or sacs, or microsporangiamicrosporangia, which are , which are often confluent (joined) in two pairs.often confluent (joined) in two pairs.

• The pollen sacs are joined to each other The pollen sacs are joined to each other and to the filament by a and to the filament by a connectiveconnective..

• Pollen grains (Pollen grains (microgametophytesmicrogametophytes) ) are produced in the pollen sacs.are produced in the pollen sacs.

GynoeciumGynoecium

• The gynoecium The gynoecium comprises all the comprises all the carpels carpels of the of the flower. Carpels are flower. Carpels are typically composed typically composed of a stigma, a of a stigma, a style, and an ovary style, and an ovary (unique to (unique to angiosperms).angiosperms).

Locule and ovuleLocule and ovule

• The compartment, cavity, or The compartment, cavity, or chamber within an ovary or anther is chamber within an ovary or anther is called a called a loculelocule. .

• OvuleOvule is the structure in seed plants is the structure in seed plants comprised of the female comprised of the female gametophyte. After fertilization, it gametophyte. After fertilization, it develops into the seed.develops into the seed.

Nectary Nectary

• A nectary is a nectar-producing gland, A nectary is a nectar-producing gland, often forming projections, lobes, or often forming projections, lobes, or disklike structures. Nectaries are often disklike structures. Nectaries are often produced near the base of the produced near the base of the androecium and gynoecium. These androecium and gynoecium. These are for the production of nectar or are for the production of nectar or other pollinator attractants, such as other pollinator attractants, such as oils or fragrances.oils or fragrances.

Three major parts of flowersThree major parts of flowers(PAG)(PAG)

• PerianthPerianth (outer protective and/or (outer protective and/or colorful structures).colorful structures).

• AndroeciumAndroecium (pl. androecia) – pollen (pl. androecia) – pollen producing structures.producing structures.

• GynoeciumGynoecium (pl. gynoecia) – ovule (pl. gynoecia) – ovule producing structures.producing structures.

Complete FlowerComplete Flower

• Has all three major parts (PAG)Has all three major parts (PAG)

• PerianthPerianth

• AndroeciumAndroecium

• GynoeciumGynoecium

Incomplete FlowerIncomplete Flower

• If one or more of the three major If one or more of the three major floral parts (PAG) is missing, the floral parts (PAG) is missing, the

flower is considered to be flower is considered to be incomplete.incomplete.

Bisexual or perfect flowerBisexual or perfect flower

• If at least the androecium and If at least the androecium and gynoecium are present, the flower is gynoecium are present, the flower is

termed bisexual or perfect.termed bisexual or perfect.

Unisexual or imperfect Unisexual or imperfect flowerflower

• If either the androecium or If either the androecium or gynoecium is lacking, the flower is gynoecium is lacking, the flower is

unisexualunisexual or or imperfectimperfect..

• If only the androecium is present, the If only the androecium is present, the flower is considered flower is considered staminatestaminate..

• If only the gynoecium is present, the If only the gynoecium is present, the flower is considered flower is considered carpellatecarpellate..

Monoecious SpeciesMonoecious Species

• In a monoecious plant species, both In a monoecious plant species, both staminate and carpellate flowers are staminate and carpellate flowers are borne on a single plant (ie pumpkins)borne on a single plant (ie pumpkins)

Dioecious speciesDioecious species

• In a dioecious plant species, the In a dioecious plant species, the staminate and carpellate flowers are staminate and carpellate flowers are borne on separate individual plants borne on separate individual plants

(ie green ash)(ie green ash)

Polygamous speciesPolygamous species

• In a polygamous plant species, there In a polygamous plant species, there are both bisexual (perfect) and are both bisexual (perfect) and unisexual (imperfect) flowers on the unisexual (imperfect) flowers on the same plant.same plant.

• Perfect flowers have both androecium Perfect flowers have both androecium and gynoecium present.and gynoecium present.

• Imperfect flowers are either staminate Imperfect flowers are either staminate or carpellate.or carpellate.

CoronaCorona

• Some flowers have an extra series of Some flowers have an extra series of floral parts, often showy, called floral parts, often showy, called coronas. These may be outgrowths coronas. These may be outgrowths of the perianth parts, stamens, or of the perianth parts, stamens, or receptacles, and they are extremely receptacles, and they are extremely diverse in form and function.diverse in form and function.

Floral SymmetryFloral Symmetry

• Radial Symmetry Radial Symmetry - Two or more - Two or more planes bisecting the planes bisecting the flower through the flower through the center will produce center will produce symmetrical halves. symmetrical halves. These flowers are These flowers are called regular.called regular.

Floral SymmetryFloral Symmetry

• Bilateral Bilateral symmetrysymmetry

• Arranged so they Arranged so they can be divided in can be divided in symmetrical halves symmetrical halves on only one plane. on only one plane. These flowers are These flowers are called irregular.called irregular.

Floral SymmetryFloral Symmetry

• Asymmetrical –Asymmetrical –

• Flowers that have Flowers that have no plane of no plane of symmetry. symmetry.

Fusion of floral partsFusion of floral parts

• ConnateConnate – petals united to petals – petals united to petals

• Distinct Distinct – petals distinct from each – petals distinct from each otherother

• AdnateAdnate – fusion of unlike parts like – fusion of unlike parts like stamens united to petals.stamens united to petals.

• FreeFree – unlike parts are not fused. – unlike parts are not fused.

Superior and inferior ovariesSuperior and inferior ovaries

• Flowers in which the perianth and Flowers in which the perianth and androecium are androecium are belowbelow the gynoecium are the gynoecium are called called hypogynoushypogynous. The ovary of such . The ovary of such flowers is said to be flowers is said to be superiorsuperior..

• Flowers in which the perianth and stamens Flowers in which the perianth and stamens appear to be attached to the upper part of appear to be attached to the upper part of the ovary are called the ovary are called epigynousepigynous. The . The ovary of such flowers is said to be ovary of such flowers is said to be inferiorinferior..

Hypogynous and epigynous Hypogynous and epigynous flowersflowers