Plants and People

Reproductive Morphology:

Flowers and Fruits

Why a Flower?

The Reproductive Structure of Flowering Plants:

PerianthPetal: CorollaSepal:Calyx

Flower Anatomy

Calyx: the outer whorl of sepals; typically these are green, but are petal-like in some species.

Flower Anatomy

Corolla: the whorl of petals, which are usually thin, soft and colored to attract animals that help the process of pollination.

The coloration may extend into the ultraviolet, which is visible to the compound eyes of insects, but not to the eyes of birds.

Flower Anatomy

Androecium (from Greek andros oikia: man's house): one or more stamens, each with a filament topped by an anther where pollen is produced.

Pollen contains the male gametes.

Flower AnatomyGynoecium (from Greek gynaikos oikia: woman's house): all the female parts—the pistil(s) with ovule(s) inside.

Flower Anatomycarpel

fertilization carpel structure

Evolution of the Carpel

See figures 3.1 and 3.2 in your book

The Carpel The carpel is the basic unit of the gynoecium. Each carpel consists of an ovary connected to a stigma by the style.

Within each carpel are one or more ovules, which will become the seed(s). The area of attachment is called the placenta (pl. = placentae) and the empty space in the chamber is called the locule (pl. = locules). The dividing walls are called the septa.

transversesection

longitudinalsection

ovule

locule

single carpel fused carpels

The Single Carpel A gynoecium with only one carpel is termed unicarpellate. A gynoecium of many separate carpels is termed apocarpous.

unicarpellate apocarpous

TS

LS

Fused CarpelsA gynoecium with many fused carpels is termed syncarpous and the flower is said to have a compound pistil.

Evolution of the fused carpel

syncarpous

Placentation

basal placentation: attachment of ovules to the bottom of the ovary. One locule, no septa.

apical placentation: The attachment of the ovules is at the apex (top) of the ovary. One locule, no septa.

Placentationparietal placentation: ovules are attached to the side walls of the ovary (or extrusions of the wall) such that an ovary usually has one locule and therefore no septa. Can only be found in a syncarpous gynoecium;

axile placentation: ovules are attached to an axis derived from the connate margins of the component carpels, such that an ovary is divided into two or more locules by septa. The ovules are borne along the central axis. Can only found in a syncarpous gynoecium.

Placentationfree or central placentation: ovules attached to a free-standing central column in a syncarpous, unilocular ovary (one locule, no septa)

marginal placentation: ovules are attached to the folded margins of the carpel, giving the appearance that there is only one elongated placenta on one side of the ovary. Can only be found in a simple pistil. This is conspicuous in legumes.

How Many Carpels? Locules?

A DCB

E F G

Flower Structure Variation

imperfect

perfect

imperfect

Flower Structure VariationOvary Position

A. ovary superior, floral parts hypogynous

B. ovary inferior, floral parts epigynous

C. ovary half-inferior

D. ovary superior, floral parts perigynous, hypanthium cup shaped

Flower Structure Variation

A flower having sepals, petals, stamens, and pistils is complete; if a flower is lacking one or more of these whorls, it is said to be incomplete.

no stamens present = incomplete

incomplete

complete

Inflorescences

An inflorescence is a group or cluster of flowers. It may be branched or unbranched. Modifications can involve the length, variations in the proportions, compressions, and swellings, and the order in which the flowers open.

Usually the modifications have been evolved to optimize the plant’s method of pollen dispersal.

Pollen Dispersal by AnimalsBees, Beetles, Bats, Birds, Butterflies, etc…

Symmetry

Flowers that are actinomorphic have "radial symmetry", meaning they can be divided into symmetrical halves by more than one plane passing through the axis, much as a pie can be cut into several equal and identical pieces.

Zygomorphic flowers have "bilateral” symmetry, where flowers can be divided by only a single plane into two mirror-image halves, much like a person's face.

Dicot versus Monocot

Dicot Monocot

Fruit and Seed FormationA fruit develops from an ovary. A seed develops from an ovule.

Dry Fruits

Dry fruits have the pericarp (fruit wall) dry at maturity. Fruits which split open to release the seeds are termed dehiscent. Those that do not split open are called indehiscent.

Indehiscent, Dry Fruits - AcheneAchene - single seeded, thin pericarp, seed coat is separate from ovary wall. Example: sunflower and strawberry “seeds”

Indehiscent, Dry Fruits - GrainGrain (caryopsis) - single seeded, pericarp fused with the ovary wall. Example: corn, wheat, rice, oats, etc.

fused

Indehiscent, Dry Fruits - NutNut - single seeded, with hard or bony pericarp, often wholly or partially surrounded by a husk of bracts. Example: hazelnut, walnut, pecan

Dehiscent, Dry Fruits - Legumes

Legume - usually dehisces along two sutures; from a simple pistil. Example: beans, peas, soybeans

one folded carpel

Unopened Legume Legume Split Open(1 carpel, 2 seams)

seed/ovule

caylx

style

Dehiscent, Dry Fruits - Capsule

Capsule - usually from a compound pistil, usually many seeded. Pericarp opens with pores or slits. Example: okra (which we eat before maturity.)

dehisces along locules(loculicidal)

okra is a capsule

seed

septa

locule

Fleshy Fruits - BerryBerry - one to multiple seeds, mesocarp is fleshy, endocarp is soft. Example: grape, tomato

Fleshy Fruits - DrupeDrupe - usually one seeded, exocarp a thin skin, mesocarp fleshy, endocarp usually hard. Example: peach, plum

Fleshy Fruits - HesperidiumHesperidium - special kind of berry with leathery rind and oil glands dotting the surface. Example: lime, orange

Fleshy Fruits - PepoPepo fruits are berrylike, with a hard rind; almost always with three carpels and parietal placentation. Examples: melon, squash

Fleshy Fruits - PomePome fruits have most of the flesh derived from a floral cup and receptacle. Example: Apple, pear

(receptacle)

Other Fruit Types (Non-Simple)

Other fruit types:

Multiple

Aggregate

Accessory

Parthenocarpic

Non-Simple Fruits - Multiple

Multipe fruits are formed by the fusion of fruits of numerous independent flowers. Example: pineapple, fig

Non-Simple Fruits - Aggregate

Aggregate fruits are those formed from several separate ovaries within a single flower. Examples: raspberry, blackberry

Non-Simple Fruits - AccessoryAccessory fruits are those where the “fruit” part is derived from something other than ovary tissue. A strawberry is a swollen receptacle and the seeds on the surface are the true fruits, called achenes.

Today’s Lab Activities• You need to get information from the prop cards to add to your chart. For each crop, record if it is a monocot or dicot, family and genus/species name, fruit type, origin and carpel number (for fruits.)

• For some, carpel number will be given and for others you will need to determine the carpel number yourself by counting the carpels by either counting locules or points of attachments for seeds in an open fruit.

• WARNING! If you have a severe allergy to poison ivy, you should not eat mango, pistachios, or cashews unless you know you are not sensitive to them

• Other than allergy concerns, you are encouraged to taste things that are new to you by cutting small pieces to eat !! Have fun!