Floral Diagram

What is Floral Diagram?

: Floral diagrams are a graphical means to describe the flowe. It is the diagrammatic design of the relative position and number of floral members in each whorl, in relation to the inflorescence or mother axis. The arrangement of floral whorl and other informations regarding the floral whorls, except the position of the ovary can be obtained from the floral diagram.

Method of floral Diagram

In order to construction of a floral diagram of a flower, the flower bud is cut transversely and examined with the help of hand lens or so called magnifying glass. The floral leaves are observed in their relevant positions and their aestivation is also clear. The stamens are also observed. Floral diagram of a characteristic bisexual flower’s are two lobed structures. The gynoecium is observed as the centralmost whorl and the chambers of ovary and placentation are noticeably observed.

Description of floral diagram

The following structures the floral diagram may be observed:

Floral Diagram

a) The mother axis is a black dot outside the furthest whorl of sepal.
b) They are followed by the bracts or bracteoles.
c) The calyx whorl are placed next with free or united sepals, the united nature is represented by in-between lines.
d) The flower portions remaining towards the axis are the anterior part, while the other side is the posterior part of it.
e) The corolla whorl follow the calyx, with free or united petals,
f) The aestivation of corolla along with the arrangement is observed e.g., papilionaceous corolla of pea or two whorled arrangement of Allium.
g) The stamens follow the corolla, which may be few or many, united stamens represented by joining lines (e.g., chinarose), epipetalous stamens represented by lines joining the stamen with corolla e.g., Solarium. The di-dynamic stamen of pea represented by line joined and one free stamen lobe.
h) The ovary is the central-most organ and the placentations are distinctly observed. Sometimes the ovary may be tilted, forming an angle with the mother axis as in family Solanaceae.

Significance of floral diagram

The fallowing matters are indicated by floral diagram:
a) Position of the mother axis can be known.
b) Presence of bracts and bractoles can be undersyand.
c) Number and aestivation of sepals and petals can be counted.
d) Number attachment and arrangement of the stamens may be counted.
e) Number of carpels, placentation and torsion of the ovary also become clear.

What is floral Formulae?

Apart from the graphical diagrams, the flower structure also can be characterized by textual formulae. Above all, they show the number of different organs, which are preceded by letters according to their type.
Tepals .....P
Sepals .....K
Petals .....C
Stamens ....A
Carpels ....G

The parts of the flower are described according to their arrangement from the outside to the inside of the said flower. If an organ type is arranged in more whorls, the outmost is denoted first, and the whorls are separated by “+”. If the organ number is large or changeable, is denoted as “∞”.