Key Points

Angiosperms are characterized by roots, stems, leaves, flowers, and fruits. The underground part forms the root system, while the part above the ground forms the shoot system.

Dicotyledonous plants, like mustard, typically have a tap root system originating from the radicle. Monocotyledonous plants, like wheat, have a fibrous root system where numerous roots arise from the base of the stem.

A root tip consists of four distinct regions: the root cap for protection, the region of meristematic activity for cell division, the region of elongation for growth, and the region of maturation with root hairs for water absorption.

The stem is the ascending part of the plant axis that bears leaves, flowers, and fruits. It is characterized by the presence of nodes, where leaves are attached, and internodes, the regions between nodes.

A typical leaf has three main parts: the leaf base, petiole, and lamina. Venation, the arrangement of veins, is typically reticulate (net-like) in dicots and parallel in monocots.

Leaves are simple when the lamina is entire, and compound when it is divided into leaflets. Phyllotaxy is the pattern of leaf arrangement on the stem, which can be alternate, opposite, or whorled.

Inflorescence is the arrangement of flowers on the floral axis. In a racemose type, the main axis continues to grow and flowers are borne laterally. In a cymose type, the main axis terminates in a flower, limiting its growth.

A flower can be actinomorphic (radial symmetry) or zygomorphic (bilateral symmetry). Based on the position of the gynoecium, flowers are hypogynous (superior ovary), perigynous (half-inferior ovary), or epigynous (inferior ovary).

Aestivation is the arrangement of sepals or petals in a floral bud. Key types include valvate (margins touch), twisted (margins overlap in one direction), imbricate (irregular overlap), and vexillary (characteristic of pea family).

The androecium is composed of stamens (male reproductive organs), and the gynoecium is composed of one or more carpels (female reproductive organs). A flower with both is bisexual.

Placentation refers to the arrangement of ovules within the ovary. The main types are marginal, axile, parietal, basal, and free central.

A fruit is a mature, ripened ovary that develops after fertilization. After fertilization, ovules develop into seeds, which consist of a seed coat and an embryo.

Dicotyledonous seeds (e.g., pea) have two cotyledons and are often non-endospermic. Monocotyledonous seeds (e.g., maize) have one large cotyledon called the scutellum and are usually endospermic.

A floral formula summarizes flower structure. Symbols include $\oplus$ (actinomorphic), % (zygomorphic), K (calyx), C (corolla), A (androecium), G (gynoecium), $\underline{G}$ (superior ovary), and brackets () for fusion.

This family is characterized by a bicarpellary, syncarpous, superior ovary with a swollen placenta. Its floral formula is $\oplus \widehat{\chi}^{7} \mathrm{~K}_{(5)} \widehat{\mathrm{C}_{(5)}} \mathrm{A}_{5} \underline{\mathrm{G}}_{(2)}$, indicating an actinomorphic, bisexual flower with 5 fused sepals, 5 fused petals, 5 stamens attached to petals, and a superior ovary with 2 fused carpels.