Biology Flower: Introduction and Vegetative Parts


`star` Flower: Introduction
`star` Flower: Types
`star` Flower: Vegetative parts


`color{blue} ul(mathtt ("Pedicel"))`: A pedicel is a stem that attaches a single flower to the inflorescence.

`color{blue} ul(mathtt ("Thalam us"))`: The swollen end of the pedicel is called thalamus or receptacle.

`color{green} ✍️ color{green} mathbf("KEY CONCEPT")`

● The flower is the `color{Violet}"reproductive unit"` in the angiosperms.

● `color{Brown}"Function"`: It is meant for `color{Violet}"sexual reproduction"`.

● `color{Brown}"Parts"`:
`star` A typical flower has a stem that attaches the single flower to the inflorescence called `color{Violet}"pedicel or stalk"`.

`star` The swollen end of the stalk or pedicel is called `color{Violet}"thalamus or receptacle"`.

`star` A typical flower has `color{Violet}"four"` different kinds of `color{Violet}"whorls"` arranged successively on the thalamus. These are `color{Violet}"calyx"`, `color{Violet}"corolla"`, `color{Violet}"androecium"` and `color{Violet}"gynoecium"`.

● `color{Brown}"Function"` : Calyx and corolla are `color{Violet}"accessory organs"`, while androecium and gynoecium are `color{Violet}"reproductive organs"`.

● In some flowers like lily, the calyx and corolla are not distinct and are termed as `color{Violet}"perianth"`.

● When a flower has both androecium and gynoecium, it is `color{Violet}"bisexual"`.

● A flower having either only stamens or only carpels is `color{Violet}"unisexual"`.


● Based on Symmetry:

`star` `color{Brown}"Actinomorphic"` : When a flower can be divided into two equal radial halves in `color{Violet}"any radial plane"` passing through the centre, it is said to be `color{Violet}"actinomorphic"`
E.g.: mustard, datura, chilli.

`star` `color{Brown}"Zygomorphic"` : When it can be divided into two similar halves only in `color{Violet}"one particular vertical plane"`, it is `color{Violet}"zygomorphic"`.
E.g.: Pea, gulmohur, bean, Cassia.

`star` `color{Brown}"Asymmetric"` : A flower is `color{Violet}"asymmetric"` (irregular) if it `color{Violet}"cannot be divided"` into two similar halves by any vertical plane passing through the centre.
E.g.: Canna.

● Based on Number of floral appendages: A flower may be `color{Violet}"trimerous"`, `color{Violet}"tetramerous"` or `color{Violet}"pentamerous"` when the floral appendages are in multiple of 3, 4 or 5, respectively

● Based on presence or absence of Bract:
`star` `color{Brown}"Bract"` : The reduced leaf found at the base of the pedicel is called Bract.

`star` Flowers with bracts are called `color{Violet}"bracteate"` and those without bracts, `color{Violet}"ebracteate"`.

● Based on position of calyx, corolla and androecium in respect of the ovary on thalamus:
`star` `color{Brown}"Hypogynous"` :
● In the `color{Violet}"hypogynous"` flower the gynoecium occupies the `color{Violet}"highest"` position while the other parts are situated `color{Violet}"below"` it.

● The ovary in such flowers is said to be `color{Violet}"superior"`
● E.g.: Mustard, China rose and Brinjal.

`star` `color{Brown}"Perigynous"` :
● If gynoecium is situated in the `color{Violet}"centre"` and other parts of the flower are located on the rim of the thalamus almost at the `color{Violet}"same level"`, it is called `color{Violet}"perigynous"`.

● The ovary here is said to be half `color{Violet}"inferior"`.

E.g.: Plum, Rose, Peach.

`star` `color{Brown}"Epigynous"` :
● In `color{Violet}"epigynous flowers"`, the margin of thalamus grows upward `color{Violet}"enclosing"` the ovary completely and getting `color{Violet}"fused"` with it, the other parts of flower arise `color{Violet}"above"` the ovary.

●The ovary is said to be `color{Violet}"inferior"`.

● E.g.: Flowers of Guava and Cucumber, and the Ray florets of Sunflower.


● `color{Violet}"Calyx"` :

`star` `color{Brown}"Position"` : The calyx is the `color{Violet}"outermost whorl"` of the flower.

`star` `color{Brown}"Members"` : Its members are called `color{Violet}"sepals"`.

`star` `color{Brown}"Features"` : Generally, sepals are `color{Violet}"green, leaf like"`.

`star` `color{Brown}"Function"` : They `color{Violet}"protect"` the flower in the `color{Violet}"bud"` stage.

`star` `color{Brown}"Type"`: The calyx may be `color{Violet}"gamosepalous"` (sepals united) or `color{Violet}"polysepalous"` (sepals free).

● `color{Violet}"Corolla"`:

`star` `color{Brown}"Members"` : Its members are called `color{Violet}"petals"`.

`star` `color{Brown}"Features"` : Petals are usually `color{Violet}"brightly colored"`. The shape and color of corolla `color{Violet}"vary greatly"` in plants. Corolla may be tubular, bell-shaped, funnel-shaped or wheel-shaped.

`star` `color{Brown}"Function"` : They `color{Violet}"attract insects"` for pollination.

`star` `color{Brown}"Type"` : corolla may be also free ( `color{Violet}"gamopetalous"`) or united ( `color{Violet}"polypetalous"`).