Ch 9Morphology of Flowering Plants — Class 11 Biology, concept-first.

Angiosperms are flowering seed plants, one of the groups of phanerogams, and they dominate the modern plant world because they are so well adapted to the conditions they grow in.

Morphologically, a flowering plant shows two broad sets of structures: vegetative structures — the root, stem and leaf — which are concerned with anchorage, nutrition and photosynthesis; and reproduct…

The root is the descending axis of the plant body. It is positively geotropic (grows towards gravity) and positively hydrotropic (grows towards water), while it is negatively phototropic (grows away f…

On the basis of their origin, roots are classified into two types:

When roots have to perform some special function in addition to, or instead of, their normal role, they undergo structural change; such roots are called metamorphosed (modified) roots.

The above-ground part of the plant body is known as the shoot system, and the stem is the main axis of this shoot system.

The stem develops several modifications to carry out additional or accessory functions.

Leaves are among the most important appendages of the plant because they carry out photosynthesis and also help remove excess water from the plant body through transpiration.

Venation is the arrangement of veins and veinlets within the leaf lamina. Veins are responsible for conducting water and minerals as well as manufactured food, and together they form the structural fr…

Based on how deeply the lamina is incised, leaves are of two main types: - Simple leaf — the lamina is entire, i.e. it is not divided all the way down to the midrib/rachis into separate leaflets.

Apart from photosynthesis, the leaf also carries out transpiration, gaseous exchange and the perception of light that triggers flowering.

Phyllotaxy is the specific manner in which leaves are arranged on the stem and its branches, and it allows each leaf to receive sufficient light.

An inflorescence is a specialised axis or branch, called the peduncle, over which flowers are produced or borne in a definite manner.

The flower is a highly modified and condensed shoot meant for sexual reproduction. On the basis of its position, a flower may be axillary or terminal.

All floral parts arise from the thalamus, one whorl per node; the thalamus is also called the torus or receptacle, and because it is green it too can carry out photosynthesis.

Angiosperms produce a fruit after fertilisation, developing from the ovary. Sometimes a fruit forms from the ovary without fertilisation occurring at all — such fruits are called parthenocarpic, and t…

A seed is the reproductive unit that develops from a fertilised, mature ovule. It is made up of a seed coat and an embryo, with or without endosperm.

A family is a group of plants that share a distinct set of common characters. Studying a family means building up a short, semi-technical description of a representative plant covering its habit, root…

Fabaceae — represented here by the Pea plant. Plants of this family are trees, shrubs or herbs. Root: the root system shows root nodules. Habit: Pea is an erect climber.

Solanaceae — represented here by the Datura plant. Plants of this family are herbs, shrubs or small trees. Root: tap root system.