Flowering Plants Morphology

Overview of Flowering Plants Morphology

• The lecture covers morphology of flowering plants, including concepts, tricks, and previous year questions for NEET.
• Topics include root systems, shoot systems, leaves, flowers, and families of flowering plants.

Root System

• The root system develops from the radicle of the embryo.
• Main functions include absorption of water and minerals, providing anchorage, storing food and nutrients, and synthesizing plant growth regulators.

Types of Root Systems

• Taproot systems feature a primary root with lateral roots, common in dicotyledonous plants, examples include mustard.
• Fibrous root systems originate from the stem's base, with thin, similar-sized roots, common in monocotyledonous plants, examples include wheat.
• Adventitious roots develop from plant parts other than the radicle.

Root Modifications

• Roots can be modified for support, food storage, and respiration.
• Prop roots in banyan trees and stilt roots in maize and sugarcane offer support.
• Sweet potatoes store food in their roots.
• Pneumatophores in mangroves facilitate respiration.

Shoot System

• The shoot system develops from the plumule of the embryo.
• Consists of the stem, leaves, flowers, and fruits.
• Primary functions include bearing leaves, flowers, and fruits, conducting water and minerals, and performing photosynthesis.

Stem Modifications

• Stems undergo modifications to perform diverse functions such as food storage, support, and protection.
• Underground stems of potatoes, ginger, turmeric, and zaminkand store food.
• Tendrils of pumpkins, watermelons, and grapevines aid in climbing.
• Thorns of citrus and Bougainvillea protect against herbivores.
• Flattened stems of Opuntia perform photosynthesis.

The Leaf

• The leaf is a lateral, flattened structure arising from the stem's node, designed for photosynthesis.
• Key parts of a leaf include the leaf base, petiole, and lamina.
• The petiole connects the leaf to the stem.
• The lamina is the expanded blade with veins and veinlets.

Venation

• Venation refers to the arrangement of veins and veinlets in a leaf.
• Reticulate venation features an irregular network of veinlets, typical in dicots.
• Parallel venation has veins running parallel to each other, common in monocots.

Types of Leaves

• Simple leaves have a single, undivided lamina.
• Compound leaves have a lamina divided into multiple leaflets.

Phyllotaxy

• Phyllotaxy is the arrangement of leaves on a stem, which can be alternate, opposite, or whorled.
• Alternate phyllotaxy features a single leaf at each node in alternating fashion.
• Opposite phyllotaxy has two leaves at each node, opposite to each other.
• Whorled phyllotaxy has more than two leaves at each node, forming a whorl.

The Flower

• The flower is the reproductive unit in angiosperms, modified for sexual reproduction.
• A typical flower has four whorls: calyx, corolla, androecium, and gynoecium.

Floral Symmetry

• Actinomorphic flowers show radial symmetry and can be divided into two equal halves in any radial plane.
• Zygomorphic flowers show bilateral symmetry and can be divided into two equal halves in only one specific vertical plane.
• Asymmetric flowers lack any symmetry.

Floral Terms

• Flowers can be described as trimerous, tetramerous, or pentamerous based on the number of floral parts in multiples of 3, 4, or 5, respectively.
• Bracteate flowers have bracts, while ebracteate flowers lack bracts.

Position of Floral Parts

• Hypogynous flowers have the gynoecium occupying the highest position, with other parts below, the ovary is superior.
• Perigynous flowers have the gynoecium in the center, with other parts at the same level, the ovary is half-inferior.
• Epigynous flowers have the gynoecium at the lowest position, with other parts above, the ovary is inferior.

Parts of a Flower

• The calyx is the outermost whorl, composed of sepals, which protect the flower in the bud stage.
• The corolla is composed of petals, which are often brightly colored to attract pollinators.
• The androecium is the male reproductive part, composed of stamens.
• The gynoecium is the female reproductive part, composed of pistils or carpels.

Aestivation

• Aestivation refers to the arrangement of sepals or petals in a floral bud.
• Valvate aestivation has sepals or petals touching each other at the margins without overlapping.
• Twisted aestivation shows one margin of the sepal or petal overlapping the next.
• Imbricate aestivation has margins of sepals or petals overlapping, but not in a specific direction.
• Vexillary aestivation, found in the pea family, features a large petal (standard) overlapping two lateral petals (wings), which in turn overlap two keels.

Androecium

• The androecium consists of stamens, each comprising a filament and an anther.
• The anther produces pollen grains.
• Stamens can be free (polyandrous) or united.

Gynoecium

• The gynoecium is the female reproductive part of the flower, consisting of one or more carpels.
• A carpel has three parts: stigma, style, and ovary.
• The ovary contains ovules, which develop into seeds after fertilization.

Placentation

• Placentation refers to the arrangement of ovules within the ovary.
• Marginal placentation features ovules along the ridge of the ovary.
• Axile placentation has ovules attached to a central axis in a multilocular ovary.
• Parietal placentation has ovules on the inner wall of the ovary.
• Free central placentation has ovules on a central axis without septa.
• Basal placentation features a single ovule at the base of the ovary.

The Fruit

• The fruit develops from the ovary after fertilization and contains seeds.
• Parts of a fruit can include the pericarp, which may be fleshy or dry.

The Seed

• The seed develops from the ovule after fertilization, containing an embryo.
• A seed consists of the seed coat, cotyledons, and an embryo axis.

Families of Flowering Plants

• Key families include Fabaceae (pea family), Solanaceae (potato family), and Liliaceae (lily family).
• Fabaceae (Leguminosae) includes economically important plants like pulses, soybeans, and groundnuts.
• Solanaceae includes plants like potatoes, tomatoes, and brinjals.
• Liliaceae is characterized by plants like lilies and tulips.

Semi-Technical Terms

• These are terms used to describe the morphology of flowering plants precisely.
• Floral formula and floral diagrams are used to represent the features of a flower.