flowers: parts and functions

FLOWERSFLOWERS..

At the end of my discussion, we should be able to:

1. know what are FLOWERS and their external parts and functions.

2. be familiar about the variations in flower structures and their collective clusters.

3. know their development of pollen grains and ovules, as well as the pollination and fertilization processes.

Objectives..

FLOWERSA. External parts of a flowerB. Variations in flower structuresC. InflorescenceD. Development of pollen grains and ovulesE. PollinationF. Fertilization

Outline…

Is a compressed shoot bearing floral leaves. They are the reproductive shoots of

angiosperm sporophytes because they cease growing and fruit are formed.

They are the most colorful as well as the most widespread and diverse members of the plant kingdom.

FLOWERS..

Are leaf-like usually colorful structures arranged in a circle called corolla around the top of a flower stem. They often have nectar and perfume at their bases.

FUNCTION:Petals support and protect the fertile structures

and also help attract pollinators.

Petals..

Petals..

Are also leaf-like, usually green and encircle the flower stem beneath the petals.

FUNCTION:Like petals, sepals also support and protect the

fertile structures and also help attract pollinators. It also cover the outside of a flower bud to protect the flower before it opens.

Sepals..

Sepals..

Is the male reproductive structure of a flower. It is made up of the filament and anther.

FUNCTION:The main function of the stamen is to produce

pollens.

Stamen..

Stamen..

Terminal structure which is a part of the stamen.

FUNCTION:Produces and contains pollens.

Anther..

Anther..

The hair-like stalk of the stamen which bears the anther.

FUNCTION:To attached the anther to the flower stem.

Filament..

Filament..

Female structure of a flower. Consists of stigma, style, ovary and ovule.

FUNCTION:The main function of the pistil is to produce

ovule.

Pistil/Carpel..

Pistil/Carpel..

Is the sticky or feathery surface on which pollen grains land and grow.

FUNCTION:Receives and captures the pollen grains and on

which they germinate.

Stigma..

Stigma..

Is the slender stalk of the pistil that the stigma sits on top of.

FUNCTION:Connects the stigma to the ovary and the place

where pollen tube grows.

Style..

Style..

The enlarge basal portion of the pistil. The structure formed at the lower end the pistil.

FUNCTION:Place where ovule/s containing eggs are formed

and produced and will eventually become the fruit.

Ovary..

Ovary..

the structures in the chamber of an ovary containing the egg cell, within the embryo sac.

FUNCTION:Carries female gametes and become seeds after

fertilization.

Ovule..

Ovule..

The peduncle is a stem, usually green, though some peduncles are more or less florally colored or neutral in color, having no particular pigmentation.

FUNCTION:The main function of peduncle is to support

inflorescence.

Peduncle..

Peduncle..

The thickened part of a stem from which the flower organs grow.

FUNCTION: The receptacle gives rise to the edible part of

the flower and fruit.

Receptacle..

Receptacle..

Calyx, the collective name for sepals of a flower. They are often green and hairy.

FUNCTION:The calyx serves as a protective covering for the

flower bud helping to protect it from insect damage and prevent it from drying out.

Calyx..

Calyx..

Collective term for all the petals of a flower. They are often brightly colored and scented.

FUNCTION: To attract insects for pollination, and act as

landing pad.

Corolla..

Corolla..

Complete flower..

Variations in flower structures..

Flower with all four whorls of floral leaves.

example: hibiscus or gumamela

Complete flower..

Flower with one or more whorls of floral leaves missing.

Example: squash and rue anemone

Incomplete flower

A perfect flower has both stamens and carpels, and may be described as "bisexual" or "hermaphroditic".

Example: lily, sacred garlic pear

Perfect flower..

A "unisexual" flower is one in which either the stamens or the carpels are missing, vestigial or otherwise non-functional.

A. Staminate- having only functional stamens and thus male.

Example: kiwi

Imperfect flower..

B. Pistillate- having only functional pistil and thus female.

Example: melon

C. Monoecious- staminate and pistillate flowers on the same plant.

Example: petunias

D. Dioecious- staminate and pistillate flower on different plants.

Example: holly

Flowers with all their flower parts are the same in size and shape.

Example: buttercup

Regular flower..

Flowers with different shape and size flower parts.

Example: orchid

Irregular flower..

is the union of unlike parts; organically united or fused with another dissimilar part.

Example:primrose

Adnation..

 The fusion of similar organs.Example: Gumamela

Connation..

Inflorescence..

The collective cluster of flowers. Some inflorescences are composed of many

small flowers arranged in a formation that resembles a single flower.

An inflorescence may include specialized stems and modified leaves known as bracts.

Inflorescence..

Single - When all the flowers are gathered in the same single pattern.

MAIN SINGLE INFLORESCENCES:Racemes- In racemes, florets are attached along

a floral peduncle with stems similar in length. Young florets appear above and the old ones below.

Inflorescences can be:

Raceme..

A spike is a raceme, but the flowers develop directly from the stem and are not borne on pedicels, as in barley (Hordeum).

Spikes..

A spadix is a spike of flowers densely arranged around it, enclosed or accompanied by a highly specialized bract called a spathe. It is characteristic of the Araceae family.

Spadix..

a flower cluster whose lower stalks are proportionally longer so that the flowers form a flat or slightly convex head.

Corymbs..

An umbel is an inflorescence which consists of a number of short flower stalks (called pedicels) which spread from a common point, somewhat like umbrella ribs. The arrangement can vary from being flat topped to almost spherical. Umbels can be simple or compound. The secondary umbels of compound umbels are known as umbellules. 

Umbels..

Umbels..

Umbels..

A head (capitulum) is a short dense spike in which the flowers are borne directly on a broad, flat peduncle, giving the inflorescence the appearance of a single flower.

Flower head/capitulum.

Flower head/capitulum.

Elongated cluster of single-sex flowers bearing scaly bracts and usually lacking petals.

Catkin/Ament..

Compound inflorescences is when a complex pattern is made of another single pattern.

MAIN COMPOUND INFLORESCENCES:

Compound Umbels- Are formed by several umbels gathered together.

Compound Inflorescences..

Compound Umbels..

Panicles are formed by several racemes gathered together.

Panicles..

 is defined as the ensemble of fruits derived from the ovaries of an inflorescence. It usually retains the size and structure of the inflorescence.

Infructescence..

Example of inflorescences..

Pollen formation occurs in the anthers, the club-shaped structures that rest on top of the numerous filaments that emerge from the center of a flower. These anthers contain structures called microsporangia that generate pollen. These microsporangia undergo meiosis, producing microspore cells that contain half of the normal amount of genetic material. Each microspore, in turn, reproduces itself several times to form a pollen grain. A single pollen grain contains two sperm cells and a cell that will grow into a tube that allows the sperm to pass into the ovule during pollination.

Development of pollen grains..

Development of pollen grains..

A similar process takes place in the ovary of the flower, which is located at the flower's base. The megasporangia in the ovary undergo meiosis, resulting in megaspores, each of which will develop into an ovule. The megaspore divides multiple times to form the structures found inside the ovule. An embryo sac, synergid cells that attract the pollen tube, cells that become a food source for the embryo, and the egg cell form from the megaspore cell. Following pollination and fertilization, each ovule becomes a seed.

Development of ovules..

Is the process of transferring pollen grains from the anther to the stigma. It is accomplished by wind, water or animals.

Pollination..

If a stigma receives pollen from the same flower on the same plant, it is self-pollinated.

Self-pollination..

If the stigma receives pollen from another flower of the same species, the flower is cross-pollinated.

Cross-pollination..

The fusion of gametes, results in diploid zygotes, which divide by mitosis and form new sporophytes.

Fertilization..

The fusion of male and female gametes (sex cells) produced by the same plant. Self-fertilization occurs in bisexual organisms.

Example: gumamela

Self-fertilization..

The process by which two sperm cell nuclei unite with two cell nuclei of the female gametophyte. The triploid nucleus will divide many times, eventually forming the endosperm of the seed.

Double-fertilization..

Double-fertilization..

- The response of flowering plants to the difference in the duration of light and dark periods in a day. Plants can be placed into three categories, depending on the day length they require for flower production.

Short day plants (example: strawberries, golden rod flower, crysanthemum)

Long day plants (example: spinach, lettuce) Neutral (example: cucumber, tomatoes, corn)

Photoperiodism..

Biology: The dynamics of Life/Texas edition/ Biggs, Kapicka, Lundgren

Botany: Introduction to Plants/ Weier, Stocking, Barbour, Rost

Biological Science/9th edition/ Campbell Biology: Concepts and Connections/6th

edition/ Campbell Plant systematics/3rd edition/ Gucharan

Singh www. Wikipedia.com/pictures www.Botanical-online.com

References..

What is the largest flower in the World? The largest flower in the world is the Rafflesia

arnoldi. It weighs approximately 7kgs and its petals grow to a meter long and 2.5cmss thick. This flower grows on the Sumatra Island of Indonesia.

Also known as the ‘corpse flower' as it emits a foul odor and attracts flies for pollination.

Did you know???

Top 5 most popular flowers in the World 1. Rose 2. Carnation 3. Chrysanthemum 4. Tulip 5. Gerbera

Did you know???

Thank you!

FAULET GALE B. ENRIQUEZBSE-BIOLOGICAL SCIENCE2nd yr./block 3Dr. Annie Cu Gallardo