Semester 3 Practical Science 1

Experiment 7

Topic:

Investigating the structures of flowers, Angiospermatophyta

Purpose:

To investigate the morphology of the Flame of the Forest (Delonix regia) flower and its

relation to its function.

Theory:

A flower consists of whorls of modified leaves which collectively produce,protect and

ensure that the union of the gametes. The whorls are attached to a receptable, the

expanded end of the flower stalk. The parts of the flower from the outside to inside are

calyx,corolla,androecium, and gynoecium.

There is wide variation in flower structure. Flowers are different species may differ in the

numbers,arrangement and the degree of the fusion of the component parts.

Radially symmetrical flowers are called actinomorphic and bilaterially symmetrical

flowers are called zygomorphic flowers.

Floral diagram provides a plan of the flower as viewed from above. It looks like a

diagrammatic cross-section.

If a bract, a leaf-like structure immediately beneath the flower, is present it should be

facing you, the flower stalk should be furthest away and the main stem of the plant

should be at the top of the flower. You will probably cut a cross-section of the ovary so

that you can show the position of the ovules on the diagram. If the petals, sepals or

stamens are joined, link them with simple brackets. If the stamens arise from the petals,

link them with radial lines.

Actinomorphic Flower Zygomorphic Flower

Figure: The two types of symmetry found in the flowers. The dotted lines indicated the planes through which the flowers can be cut so as to give two equal and opposite halves.

Half-FlowerA

Transverse-section (floral diagram)B

C Floral Formula

K5 C5 A5 G1

Stamens: androecium (A)

Carpel: gynoecium (G)Petals: corolla (C)

Sepals: calyx (K)

Figure: Three representations of the structure of the flower

Apparatus and materials:

Flame of the Forest Flowers

A sharp scalpel/razor blade

Hand lens

Procedure:

1. The flower is cut into equal halves using a sharp scalpel.

2. A large labeled drawing is made for the dissected flower as well as the floral

diagram.

3. The drawing scale is stated.

Half-flower section Transverse section

Diagram of selected Actinomorphic flower

Diagram of selected Zygomorphic flower

Discussion:

Flowers have different parts of structure with different functions. Sepals are a

leaf-like structure that protects young flower bud while petals are often served to attract

pollinators to the plant. Stamens is male part of the flower, consisting of

the anther and filament, makes pollen grains .The filament is the stalk of the stamen

which bears the anther and follows by anther is the pollen bearing portion of a stamen.

Besides, stigma is a sticky part of the flower that serves as a receptive surface

for pollen grains and the style is the stalk of a carpel which is between the stigma and

the ovary, through which the pollen tube grows.

An ovary is enlarged base of the carpel containing the ovule or ovules that when

it matures become a fruit. An ovule is located in the ovaries that carries female

gametes and undergo fertilization to become seed. A receptacle is a part of flower stalk

bearing the floral organs, at base of flower.

Based on my observation of two types of selected flowers, these two types of

flowers have various differences that we can see from the diagram and drawing above.

The actinomorphic flower has five petals that differ with a zygonomorphic flower

which commonly has two petals. Plus, the actinomorphic flower can be divided into 3 or

more identical sector that is related to each other by rotation about the centre of the

flower. While zygomorphic flower can only be divided a single plane into two mirror-

image halves which is much like a yoke shape.

Apart from that, actinomorphic flower is called radially symmetrical flower while

the zygomorphic flower is called bilaterially flower.

Conclusion:

Actinomorphic flowers have different characteristics that differ than zygomorphic

flowers.

Preparatory Programme Bachelor of Education

(Program Persediaan Ijazah Sarjana Muda Pendidikan)

Biology Report (SN3311)

Name : Jessica Bongsam

IC No : 920823-13-5160

Group/Unit : 3 PPISMP-SCIENCE

Lecturer Name : Madam Che Zaini binti Che Chik