flowers in review. basic flower a flower described: a characteristic feature of the angiosperms is...

Flowers in ReviewFlowers in Review

Basic FlowerBasic Flower

A flower described:A flower described:

A characteristic feature of the A characteristic feature of the angiospermsangiosperms is the is the groupinggrouping of of sexually reproductive structures with sexually reproductive structures with sterile auxiliary ones into a single unit sterile auxiliary ones into a single unit known as the known as the flowerflower..

Most consider the Most consider the flowerflower to represent a to represent a shortened branchshortened branch bearing several kinds bearing several kinds of of modified leavesmodified leaves..

A flower described:A flower described: Part II Part II

The sepals and petals (calyx and corolla) The sepals and petals (calyx and corolla) are sterile (non-reproductive).are sterile (non-reproductive).

The inner two whorls of a flower, The inner two whorls of a flower, stamens (microsporophylls) and carpels stamens (microsporophylls) and carpels (megasporophylls) are reproductive. (megasporophylls) are reproductive.

Stamens and carpels produce spores for Stamens and carpels produce spores for sexual reproduction through the process sexual reproduction through the process of meiosis.of meiosis.

Perianth Perianth (the calyx and corolla (the calyx and corolla

collectively)collectively) The The perianthperianth is the set of sterile flower parts is the set of sterile flower parts

that surround the stamens and carpels.that surround the stamens and carpels. The perianth is The perianth is biseriatebiseriate if it consists of an if it consists of an

outer ring of sepals and an inner ring of petals. outer ring of sepals and an inner ring of petals. The perianth is The perianth is uniseriateuniseriate is only one ring of is only one ring of

perianth parts is present.perianth parts is present. If only one ring of perianth parts is present, the If only one ring of perianth parts is present, the

present parts are considered sepals, and the present parts are considered sepals, and the missing parts are considered petals.missing parts are considered petals.

Calyx Facts ICalyx Facts I

Sepals are most commonly green and Sepals are most commonly green and leaf-like (leaf-like (sepaloidsepaloid), but it is not ), but it is not uncommon for them to have the color uncommon for them to have the color and texture of petals (and texture of petals (petaloidpetaloid).).

Sepals may be distinct or variously Sepals may be distinct or variously connateconnate..

A calyx of connate sepals is A calyx of connate sepals is synsepaloussynsepalous..

Calyx Facts IICalyx Facts II

The fused portion of a synsepalous calyx is a The fused portion of a synsepalous calyx is a calyx tubecalyx tube..

The separate tips of a calyx are called The separate tips of a calyx are called calyx calyx lobeslobes..

Sepals may be entirely missing in some cases.Sepals may be entirely missing in some cases. Sepals may fall off as the flower opens Sepals may fall off as the flower opens

((caducous sepalscaducous sepals).). Sepals may persist through various lengths of Sepals may persist through various lengths of

time in flowering and fruiting.time in flowering and fruiting.

Corolla FactsCorolla Facts

The corolla is the inner of the two sterile The corolla is the inner of the two sterile whorls when both whorls are present.whorls when both whorls are present.

Petals are often brightly colored, but they Petals are often brightly colored, but they are sepaloid (green and leaf-like) in some are sepaloid (green and leaf-like) in some flowers.flowers.

Generally, if the number of sepals and Generally, if the number of sepals and petals is the same, the petals alternate petals is the same, the petals alternate with the sepals.with the sepals.


A flower that lacks A flower that lacks petals is petals is apetalousapetalous..


A flower that has A flower that has distinct (separate) distinct (separate) petals is petals is apopetalous.apopetalous.


An individual petal An individual petal sometimes has a sometimes has a thin, stalk-like basal thin, stalk-like basal portion called a portion called a clawclaw and an expanded and an expanded upper portion called upper portion called a a bladeblade..

Corolla Facts IIICorolla Facts III

A flower that has connate petals into a A flower that has connate petals into a ring or a tube may be described as ring or a tube may be described as sympetaloussympetalous. .

Sympetalous corollas often have a Sympetalous corollas often have a cylindrical basal cylindrical basal tubetube, a gradually , a gradually expandingexpanding throat throat, and a flaring , and a flaring limblimb. . This limb is usually lobed.This limb is usually lobed.

Sympetalous corollaSympetalous corolla

Corolla Facts IVCorolla Facts IV

A sympetalous corolla with bilateral A sympetalous corolla with bilateral symmetry is often symmetry is often bilabiatebilabiate (two-lipped). (two-lipped). From the side it looks like an open mouth From the side it looks like an open mouth with an upper lip (usually 2 lobes) and a with an upper lip (usually 2 lobes) and a lower lip (usually 3 lobes).lower lip (usually 3 lobes).

Bilabiate Sympetallous Bilabiate Sympetallous CorollaCorolla

Sympetallous Corolla Sympetallous Corolla ShapesShapes

Androecium FactsAndroecium Facts

The androecium consists of the stamens of the The androecium consists of the stamens of the flower, usually arranged in a spiraled or flower, usually arranged in a spiraled or whorled pattern.whorled pattern.

Stamens are located around the gynoecium if Stamens are located around the gynoecium if carpels are present (bisexual flower or perfect carpels are present (bisexual flower or perfect flower).flower).

Stamens are located in the center of the flower Stamens are located in the center of the flower if the gynoecium is absent (unisexual flower or if the gynoecium is absent (unisexual flower or imperfect flower).imperfect flower).


Most stamens consist of a narrow thread-Most stamens consist of a narrow thread-like like filamentfilament (stalk) bearing a terminal, 2- (stalk) bearing a terminal, 2-4 lobed sac-like 4 lobed sac-like anther anther filled with filled with pollenpollen..

Occasionally, the filaments are absent or Occasionally, the filaments are absent or nearly so, and the anthers are attached nearly so, and the anthers are attached directly to the receptacle (the portion of directly to the receptacle (the portion of the pedicel upon which the flower parts the pedicel upon which the flower parts are borne).are borne).


Rarely, stamens are broad and leaf like.Rarely, stamens are broad and leaf like. In most plants, an anther is composed of 2-4 In most plants, an anther is composed of 2-4

pollen sacs joined by a sterile region called the pollen sacs joined by a sterile region called the connectiveconnective..

Stamens may be fertile or sterile. Fertile Stamens may be fertile or sterile. Fertile stamens produce pollen.stamens produce pollen.

Staminodes (sterile stamens) have lost the Staminodes (sterile stamens) have lost the ability to make pollen and are extremely ability to make pollen and are extremely variable in form and size. Staminodes may variable in form and size. Staminodes may secrete nectar.secrete nectar.

Typical StamenTypical Stamen


Stamens may be distinct and free or Stamens may be distinct and free or variously fused to each other (connate) variously fused to each other (connate) or to other parts of the flower (adnate).or to other parts of the flower (adnate).


If the filaments of all the stamens are connate If the filaments of all the stamens are connate into a ring, the stamens are into a ring, the stamens are monadelphous monadelphous (united in one group).(united in one group).


In many members of the Fabaceae In many members of the Fabaceae family, the stamens are family, the stamens are diadelphousdiadelphous (in (in two groups). In such plants, there are two groups). In such plants, there are ten stamens, nine of which are connate ten stamens, nine of which are connate by their filaments into a U-shaped tube by their filaments into a U-shaped tube and one which is distinct.and one which is distinct.

In several other families, stamens are In several other families, stamens are connate in bunches, often with several to connate in bunches, often with several to many stamens each. many stamens each.


In the very large sunflower (Asteraceae) In the very large sunflower (Asteraceae) family and a few other families, the family and a few other families, the filaments are distinct, but the anthers are filaments are distinct, but the anthers are connate, forming a tube that surrounds connate, forming a tube that surrounds the style.the style.


Stamens may be Stamens may be adnate to other parts adnate to other parts of the flower. In this of the flower. In this illustration, the illustration, the stamens are adnate stamens are adnate to the corolla to the corolla (petals). These are (petals). These are considered considered epipetalousepipetalous stamens.stamens.


The number of stamens in a flower is The number of stamens in a flower is extremely variable. extremely variable.

Stamens may be fewer than, equal to, Stamens may be fewer than, equal to, twice as many, or more than twice as twice as many, or more than twice as many as the petals. many as the petals.


When the stamens When the stamens are as many as or are as many as or fewer than the fewer than the petals, they are petals, they are alternate with the alternate with the petals if they attach petals if they attach between the petals.between the petals.


When the stamens When the stamens are as many as or are as many as or fewer than the petals fewer than the petals and if they attach and if they attach directly in front of the directly in front of the petals they are petals they are considered considered oppositeopposite..

Gynoecium FactsGynoecium Facts

The carpels form the terminal or The carpels form the terminal or centermost whorl of parts on the flower.centermost whorl of parts on the flower.

The carpels are the basic units of the The carpels are the basic units of the gynoecium.gynoecium.

Another term used often to describe the Another term used often to describe the gynoecium is pistil. gynoecium is pistil.


The gynoecium consists of the ovary, The gynoecium consists of the ovary, one or more stigmas (pollen receptive one or more stigmas (pollen receptive surfaces), and usually one or more styles surfaces), and usually one or more styles (slender connections between stigma (slender connections between stigma and ovary).and ovary).


Some angiosperms have only a single Some angiosperms have only a single carpel per flower. These have a carpel per flower. These have a monocarpous gynoecium. monocarpous gynoecium.

Some flowers have two or more carpels. Some flowers have two or more carpels. If the carpels are distinct from each other, If the carpels are distinct from each other,

the gynoecium is the gynoecium is apocarpousapocarpous.. If the carpels are fused (connate), the If the carpels are fused (connate), the

gynoecium is gynoecium is syncarpoussyncarpous..


A one-carpellate pistil is a simple pistil. A one-carpellate pistil is a simple pistil. Simple pistils are evident in Simple pistils are evident in monocarpous and apocarpous monocarpous and apocarpous gynoeciums.gynoeciums.

When two or more carpels are connate, a When two or more carpels are connate, a syncarpous gynoecium is formed. The syncarpous gynoecium is formed. The resulting stucture is called a compound resulting stucture is called a compound pistil.pistil.

PlacentationPlacentation

Placentation is the attachment of ovules Placentation is the attachment of ovules (immature seeds) within the interior of an (immature seeds) within the interior of an ovary. The placement of the ovules in ovary. The placement of the ovules in quite variable and is dependent on the quite variable and is dependent on the number of carpels, their degree of fusion, number of carpels, their degree of fusion, and evolutionary modifications of the and evolutionary modifications of the interior of the ovary and its contents. interior of the ovary and its contents.

Ovary Position and Ovary Position and Insertion PointsInsertion Points

The ovary is generally directly attached The ovary is generally directly attached directly to the receptacle. The other directly to the receptacle. The other flower whorls are also attached to the flower whorls are also attached to the receptacle, but their apparent place of receptacle, but their apparent place of attachment may be to the rim of a attachment may be to the rim of a hypanthium or to the sides or top of the hypanthium or to the sides or top of the ovary. The apparent point of attachment ovary. The apparent point of attachment of the outer floral parts relative to the of the outer floral parts relative to the ovary is their place of insertion.ovary is their place of insertion.

Ovary Position and Ovary Position and Insertion PointsInsertion Points

If the bases of the If the bases of the perianth parts are perianth parts are attached directly to the attached directly to the receptacle, the insertion receptacle, the insertion is hypogynous.is hypogynous.

The ovary of such a The ovary of such a flower is superior (free flower is superior (free from the bases of the from the bases of the outer parts of the flower).outer parts of the flower).

Ovary Position and Ovary Position and Insertion PointInsertion Point

If the flower has a If the flower has a hypanthium, the hypanthium, the apparent point of apparent point of attachment of the attachment of the outer flower parts is outer flower parts is the rim of the the rim of the hypantium rather hypantium rather than the receptacle.than the receptacle.

The ovary is The ovary is superior.superior.


If the bases of the If the bases of the perianth parts and perianth parts and stamens are directly stamens are directly adnate to the ovary adnate to the ovary wall the insertion is wall the insertion is epigynous (the top of epigynous (the top of the ovary).the ovary).

The ovary is inferior.The ovary is inferior.


If the bases of the If the bases of the perianth parts and perianth parts and stamens are adnate to stamens are adnate to the ovary wall as a the ovary wall as a hypanthium, the insertion hypanthium, the insertion is epigynousis epigynous

The ovary is inferior.The ovary is inferior. A flower with an inferior A flower with an inferior

ovary always has a ovary always has a epigynous insertion.epigynous insertion.

NectariesNectaries

Flowers that are animal/insect-pollinated often Flowers that are animal/insect-pollinated often bear nectaries.bear nectaries.

These are secretory glands that exude a These are secretory glands that exude a solution of sugars or other substances that are solution of sugars or other substances that are gathered by animals for food.gathered by animals for food.

Some flowers have a nectary disc that sits Some flowers have a nectary disc that sits below or surrounds the base of the ovary.below or surrounds the base of the ovary.

Some flowers produce nectar inside spurs that Some flowers produce nectar inside spurs that jut from the surface of the perianth part.jut from the surface of the perianth part.

The EndThe End

flowers in review. basic flower a flower described: a characteristic feature of the angiosperms is...

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