Ch 5Morphology of Flowering Plants — Class 11 Biology, concept-first.

Angiosperms, the flowering plants, show an enormous range of external form — yet however different two flowering plants may look, each is still built from the same handful of organs: roots, stems, lea…

If you pull out any weed you will notice that all of them have roots, stems and leaves, and may also bear flowers and fruits.

The root is covered at the apex by a thimble-like structure called the root cap. It protects the tender apex of the root as it makes its way through the soil.

What are the features that distinguish a stem from a root? The stem is the ascending part of the axis bearing branches, leaves, flowers and fruits.

The leaf is a lateral, generally flattened structure borne on the stem. It develops at the node and bears a bud in its axil. The axillary bud later develops into a branch.

The lamina, or leaf blade, is the green expanded part of the leaf and is traversed by veins and veinlets.

Leaves are classified into two basic kinds — simple and compound — depending on whether the lamina remains entire or is broken up into separate units.

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. It describes how the leaves are positioned at the nodes as one moves along the axis, and it is usually of three types — altern…

A flower is essentially a modified shoot: at the tip of this shoot the shoot apical meristem changes into a floral meristem.

The flower is the reproductive unit in the angiosperms, meant for sexual reproduction. Morphologically it is a modified shoot in which the shoot apical meristem changes to a floral meristem; the inter…

Each flower normally has four floral whorls, namely the calyx, corolla, androecium and gynoecium, arranged successively on the thalamus.

The calyx is the outermost whorl of the flower, and its individual members are called sepals. The sepals are generally green and leaf-like, and their main role is to enclose and protect the other, mor…

The corolla is composed of petals. Petals are usually brightly coloured to attract insects for pollination.

The androecium is composed of stamens and represents the male reproductive whorl. Each stamen consists of a stalk or filament and an anther.

The gynoecium is the female reproductive part of the flower and is made up of one or more carpels. A carpel consists of three parts, namely the stigma, style and ovary.

The fruit is a characteristic feature of the flowering plants. It is a mature or ripened ovary, and it develops only after fertilisation of the flower.

The ovules, after fertilisation, develop into seeds. A seed is therefore the fertilised, mature ovule. Structurally, a seed is made up of two main parts:

The outermost covering of a dicotyledonous seed is the seed coat, which is made up of two layers:

Generally, monocotyledonous seeds are endospermic, but some, as in orchids, are non-endospermic. The seed structure of a cereal grain such as maize illustrates the typical monocotyledonous condition.

Various morphological features are used to describe a flowering plant. The description has to be brief, in simple and scientific language and presented in a proper sequence.

Solanaceae is a large family, commonly called the 'potato family'. It is widely distributed in tropics, subtropics and even the temperate zones, and includes several plants of great economic importanc…

Flowering plants (angiosperms) show great diversity in external form, yet they are all built on a common plan of roots, stems, leaves, flowers, fruits and seeds.

Higher-order thinking / exemplar-style practice problems.