Flowering plants, or angiosperms, exhibit a remarkable diversity in their external structure and form. Despite this wide variation, most higher plants share fundamental characteristics: the presence of roots, stems, leaves, flowers, and fruits.

Understanding the morphology (external structure) of flowering plants requires knowing standard technical terms and definitions. It also involves recognizing how plant parts can be modified to adapt to different environments or perform specific functions like support, storage, protection, climbing, etc.

A typical flowering plant body is organized into two main systems:

• The Root System: The underground part.
• The Shoot System: The part above the ground, consisting of the stem, leaves, flowers, and fruits.

The Root

The root is typically the underground part of a flowering plant.

In most dicotyledonous plants, the root system originates from the direct elongation of the radicle (the embryonic root) of the seed.

• This elongation forms the primary root.
• The primary root produces lateral branches of various orders (secondary, tertiary roots, etc.).
• The primary root and its lateral branches together constitute the tap root system (e.g., Mustard).

In monocotyledonous plants, the primary root is short-lived.

• It is replaced by a large number of roots that originate from the base of the stem.
• These roots form the fibrous root system (e.g., Wheat).

Some plants develop roots from parts of the plant other than the radicle, such as the stem or leaves. These are called adventitious roots (e.g., Grass, *Monstera*, Banyan tree).

The main functions of the root system are:

• Absorption of water and minerals from the soil.
• Providing anchorage and support to the plant.
• Storing reserve food materials.
• Synthesizing plant growth regulators.

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Regions Of The Root

The tip of a root is covered by a protective, thimble-like structure called the root cap. It safeguards the delicate root apex as it pushes through the soil.

Just a few millimeters above the root cap is the region of meristematic activity. The cells here are small, thin-walled, dense, and divide rapidly.

Above the meristematic region is the region of elongation. Cells in this zone enlarge and elongate quickly, causing the root to grow in length.

Proximal to the region of elongation is the region of maturation. Cells in this area differentiate and mature. Some epidermal cells here form fine, thread-like structures called root hairs, which are responsible for absorbing water and minerals from the soil.

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Modifications Of Root

Roots can change their form and structure to perform additional functions besides absorption and conduction.

• Storage: Tap roots of plants like carrot and turnip, and adventitious roots of sweet potato, swell up to store food reserves.
• Support:
  • Prop roots: Hanging structures that grow from branches into the soil, providing support to large trees like the Banyan tree.
  • Stilt roots: Supporting roots arising from the lower nodes of the stem, found in plants like maize and sugarcane.
• Respiration: In some plants growing in swampy areas (where soil lacks oxygen), roots grow vertically upwards out of the ground. These are called pneumatophores and help the roots obtain oxygen for respiration (e.g., *Rhizophora*).

The Stem

The stem is typically the ascending part of the plant axis. It develops from the plumule of a germinating seed.

Key features distinguishing a stem from a root:

• Presence of nodes and internodes. Nodes are the points on the stem where leaves are attached. Internodes are the segments of the stem between two successive nodes.
• Bears leaves, branches, flowers, and fruits.
• Possesses buds (terminal at the apex or axillary in the leaf axil).
• Usually green when young, later becoming woody and darker.

Main functions of the stem:

• Provides support and holds branches, leaves, flowers, and fruits.
• Conducts water, minerals (upwards), and photosynthates (food, usually downwards) between the roots and other plant parts.

Besides these primary roles, stems can be modified to perform other functions.

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Modifications Of Stem

Stems can be modified in various ways to serve functions beyond their typical role:

• Underground Storage: Some stems grow underground and swell up to store food, also acting as organs of perennation (survival during unfavorable conditions) (e.g., Potato, Ginger, Turmeric, Zaminkand, Colocasia).
• Support:
  • Stem tendrils: Slender, spirally coiled structures developed from axillary buds. They help plants climb (e.g., Gourds like cucumber, pumpkins, watermelon, and Grapevines).
• Protection:
  • Thorns: Woody, straight, pointed structures modified from axillary buds. They protect plants from grazing animals (e.g., *Citrus*, *Bougainvillea*).
• Photosynthesis: In some arid region plants, stems are modified into flattened (*Opuntia*) or fleshy cylindrical (*Euphorbia*) structures containing chlorophyll. They take over the function of photosynthesis when leaves are reduced or absent.
• Vegetative Propagation and Spread:
  • Runners: Underground stems that spread laterally in the soil. New plants are formed from nodes when older parts die (e.g., Grass, Strawberry).
  • Stolon: A slender lateral branch arising from the base of the main axis. After growing aerially, it arches downwards to touch the ground, where a new plant develops (e.g., Mint, Jasmine).
  • Offset: A short lateral branch with short internodes, found in aquatic plants. Each node bears a rosette of leaves above and a tuft of roots below, allowing rapid vegetative spread (e.g., *Pistia*, *Eichhornia*).
  • Sucker: Lateral branches originating from the basal, underground part of the main stem. They grow horizontally beneath the soil and then emerge obliquely upwards to form leafy shoots (e.g., Banana, Pineapple, *Chrysanthemum*).

The Leaf

The leaf is a lateral outgrowth of the stem, typically flattened and green. It develops at a node on the stem and has a bud (the axillary bud) in its axil. The axillary bud can later develop into a branch.

Leaves originate from the shoot apical meristems and are usually arranged in an acropetal order (youngest leaves near the apex, oldest at the base).

Leaves are the primary vegetative organs responsible for photosynthesis.

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A typical leaf consists of three main parts:

1. Leaf Base: The part by which the leaf is attached to the stem. It may bear two small, leaf-like lateral structures called stipules. In monocots, the leaf base often expands into a sheath that partially or fully covers the stem. In some leguminous plants, the leaf base is swollen and called a pulvinus, which is involved in leaf movements (like closing at night).
2. Petiole: The stalk of the leaf that connects the lamina to the stem. A long, flexible petiole allows the leaf blade to move freely in the wind, which helps cool the leaf surface and brings fresh air for gas exchange.
3. Lamina (Leaf Blade): The green, expanded part of the leaf. It contains veins and veinlets. The prominent central vein is called the midrib. Veins provide structural rigidity to the lamina and serve as channels for the transport of water, minerals, and food. The lamina varies in shape, margin, apex, surface, and the degree of incisions in different plants.

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Venation

Venation refers to the arrangement pattern of veins and veinlets within the leaf lamina.

• Reticulate Venation: The veinlets form a network. This type of venation is characteristic of leaves in most dicotyledonous plants.
• Parallel Venation: The veins run parallel to each other within the lamina, without forming a network. This is a characteristic feature of leaves in most monocotyledonous plants.

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Types Of Leaves

Leaves are classified based on whether the lamina is divided into leaflets:

• Simple Leaf: The lamina is either completely undivided (entire) or, if incised (cut), the incisions do not reach the midrib.
• Compound Leaf: The incisions of the lamina extend all the way to the midrib, dividing the leaf blade into a number of smaller units called leaflets.

A bud is always present in the axil of the petiole of both simple and compound leaves, but *not* in the axil of the individual leaflets of a compound leaf.

Compound leaves are mainly of two types:

1. Pinnately Compound Leaf: A number of leaflets are arranged along a common axis called the rachis, which represents the midrib of a simple leaf (e.g., Neem).
2. Palmately Compound Leaf: The leaflets are all attached at a single point, specifically at the tip of the petiole (e.g., Silk cotton).

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Phyllotaxy

Phyllotaxy is the specific pattern or arrangement of leaves on the stem or a branch. The main types of phyllotaxy are:

• Alternate: A single leaf arises at each node, alternating in direction along the stem (e.g., China rose, Mustard, Sunflower).
• Opposite: A pair of leaves arises at each node, positioned directly opposite to each other (e.g., *Calotropis*, Guava).
• Whorled: More than two leaves arise at a single node and are arranged in a circle or whorl around the stem (e.g., *Alstonia*).

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Modifications Of Leaves

Leaves can be modified to perform functions other than photosynthesis:

• Leaf Tendrils: Entire leaves or parts of leaves are modified into slender, coiling structures that help the plant climb (e.g., Pea).
• Spines: Leaves are modified into sharp, pointed structures for defense against herbivores (e.g., Cacti).
• Fleshy Leaves: Thick, fleshy leaves modified for storing food and water (e.g., Onion, Garlic).
• Phyllode: In some plants (e.g., Australian acacia), the true leaves are small and short-lived. The petioles expand, become green, and take over the function of photosynthesis.
• Insect Traps: Leaves are modified into specialized structures for trapping insects, supplementing nitrogen nutrition (e.g., Pitcher plant, Venus-fly trap).

The Inflorescence

A flower is essentially a modified shoot. The shoot apical meristem undergoes a transformation into a floral meristem.

During this transformation, internodes do not elongate, resulting in a condensed axis. The apex produces floral appendages (like sepals, petals, stamens, and carpels) laterally at successive nodes, instead of leaves.

When a shoot tip directly converts into a single flower, the flower is said to be solitary.

Inflorescence refers to the specific arrangement of flowers on the floral axis (the part of the stem bearing the flowers).

The type of inflorescence depends on whether the apical meristem of the floral axis develops into a flower or continues to grow. Two main types are recognized:

• Racemose Inflorescence: The main axis of the inflorescence continues to grow indefinitely. Flowers are borne laterally on this axis in an acropetal succession (youngest flowers are at the apex, and the oldest are at the base).
• Cymose Inflorescence: The main axis terminates in a flower, thus limiting its growth. Flowers are borne in a basipetal order (oldest flowers are at the apex where the main axis ends, and the youngest are towards the base).

The Flower

The flower is the specialized reproductive unit of angiosperms, responsible for sexual reproduction.

A typical flower is attached to the stem by a stalk called the pedicel. The swollen tip of the pedicel, where the floral parts are arranged, is called the thalamus or receptacle.

A complete flower usually has four distinct whorls (rings of floral parts) arranged successively on the thalamus:

• Calyx (outermost whorl)
• Corolla
• Androecium
• Gynoecium (innermost whorl)

The calyx and corolla are considered accessory organs as they primarily support and protect the reproductive organs.

The androecium and gynoecium are the reproductive organs.

In some flowers (e.g., lily), the calyx and corolla are indistinguishable and are collectively termed the perianth.

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Sexuality of Flowers:

• Bisexual: A flower possessing both androecium (male) and gynoecium (female).
• Unisexual: A flower having either only androecium (male flower) or only gynoecium (female flower).

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Symmetry of Flowers:

• Actinomorphic (Radial symmetry): The flower can be divided into two equal radial halves by any vertical plane passing through the center (e.g., Mustard, Datura, Chilli). Represented by the symbol $\textsf{Å}$.
• Zygomorphic (Bilateral symmetry): The flower can be divided into two similar halves by only one specific vertical plane (e.g., Pea, Gulmohur, Bean, Cassia). Represented by the symbol $\textsf{\%}$.
• Asymmetric (Irregular): The flower cannot be divided into two similar halves by any vertical plane (e.g., Canna).

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Number of Floral Appendages:

• Trimerous: Floral parts are in multiples of three.
• Tetramerous: Floral parts are in multiples of four.
• Pentamerous: Floral parts are in multiples of five.

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Presence of Bracts:

• Bracteate: Flowers with reduced leaves (bracts) at the base of the pedicel.
• Ebracteate: Flowers without bracts.

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Position of Floral Parts on Thalamus relative to Ovary:

This determines the position of the ovary and is used for classification (Figure 5.13).

• Hypogynous: The gynoecium (ovary) is in the highest position on the thalamus, and the other floral parts (calyx, corolla, androecium) are located below it. The ovary is described as superior (e.g., Mustard, China rose, Brinjal).
• Perigynous: The gynoecium is in the center, and the other floral parts are located on the rim of the thalamus, almost at the same level as the ovary. The ovary is described as half inferior (e.g., Plum, Rose, Peach).
• Epigynous: The margin of the thalamus grows upwards and completely encloses the ovary, fusing with it. The other floral parts arise above the ovary. The ovary is described as inferior (e.g., Guava, Cucumber, Ray florets of Sunflower).

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Parts Of A Flower

As mentioned, a typical flower has four main whorls (Figure 5.14):

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Calyx

The calyx is the outermost whorl of the flower. Its individual members are called sepals.

Function: Sepals are usually green and leaf-like, providing protection to the flower in the bud stage.

Nature: Sepals can be:

• Gamosepalous: When the sepals are united (fused).
• Polysepalous: When the sepals are free.

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Corolla

The corolla is the whorl located inside the calyx. It is composed of petals.

Function: Petals are usually brightly coloured and often fragrant to attract insects and other pollinators.

Nature: Like sepals, petals can be:

• Gamopetalous: When the petals are united (fused).
• Polypetalous: When the petals are free.

The shape and colour of the corolla are highly varied in different plants, potentially being tubular, bell-shaped, funnel-shaped, or wheel-shaped.

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Aestivation

Aestivation is the term describing the specific mode of arrangement of sepals or petals relative to one another within a floral bud of the same whorl. The main types of aestivation are (Figure 5.15):

• Valvate: Sepals or petals in a whorl just touch each other at the margin without overlapping (e.g., *Calotropis*).
• Twisted: One margin of each sepal or petal overlaps the margin of the next one in a consistent direction (like a twist) (e.g., China rose, Lady's finger, Cotton).
• Imbricate: The margins of sepals or petals overlap one another, but there is no particular or regular direction to the overlap (e.g., Cassia, Gulmohur).
• Vexillary (Papilionaceous): A specialized type of aestivation found in pea and bean flowers (Fabaceae). There are five petals: the largest posterior petal (standard) overlaps the two lateral petals (wings), which in turn overlap the two smallest anterior petals (keel). The keel petals are often slightly fused and enclose the stamens and pistil.

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Androecium

The androecium is the male reproductive whorl of the flower. It is composed of one or more stamens.

Structure of Stamen: Each stamen consists of two main parts: a stalk or filament and a swollen tip called the anther.

Pollen Production: The anther is typically bilobed (has two lobes), and each lobe contains two chambers called pollen-sacs. Pollen grains, which contain the male gametes, are produced inside the pollen-sacs.

Staminode: A stamen that is sterile (does not produce functional pollen) is called a staminode.

Adhesion (Attachment to other whorls): Stamens can be attached to other floral parts:

• Epipetalous: Stamens attached to the petals (e.g., Brinjal).
• Epiphyllous: Stamens attached to the perianth (when calyx and corolla are indistinguishable, e.g., Lily).

Cohesion (Union among themselves): Stamens within a flower can be free or united in varying degrees:

• Polyandrous: Stamens remain completely free from each other.
• Monoadelphous: Filaments are united into a single bundle or column, but the anthers are free (e.g., China rose).
• Diadelphous: Filaments are united into two bundles (e.g., Pea).
• Polyadelphous: Filaments are united into more than two bundles (e.g., *Citrus*).

Variations: There can also be variations in the length of filaments within a single flower (e.g., *Salvia*, Mustard).

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Gynoecium

The gynoecium is the female reproductive whorl of the flower. It is made up of one or more units called carpels or pistils.

Structure of Carpel: Each carpel typically has three parts:

1. Ovary: The swollen basal part, containing one or more ovules.
2. Style: An elongated stalk extending upwards from the ovary.
3. Stigma: The receptive tip of the style, where pollen grains land during pollination.

Ovule Attachment: Within the ovary, ovules are attached to a flattened cushion-like tissue called the placenta.

Cohesion (Union among Carpels): When a flower has more than one carpel, they can be:

• Apocarpous: Carpels are free (e.g., Lotus, Rose).
• Syncarpous: Carpels are united (fused) (e.g., Mustard, Tomato).

Post-Fertilisation: After fertilization, the ovules develop into seeds, and the ovary matures into a fruit.

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Placentation

Placentation refers to the specific arrangement of ovules within the ovary. Different types include (Figure 5.16):

• Marginal: The placenta forms a ridge along the ventral suture (the line of fusion of the edges) of a monocarpellary ovary. Ovules are borne on this ridge in two rows (e.g., Pea).
• Axile: The placenta is axial, and the ovules are attached to it in a multicarpellary, syncarpous ovary that is divided into chambers (locules) by septa (e.g., China rose, Tomato, Lemon).
• Parietal: Ovules develop on the inner wall of the ovary or on its peripheral part. The ovary is typically one-chambered (unilocular) but may become two-chambered due to the formation of a false septum (e.g., Mustard, *Argemone*).
• Free Central: Ovules are borne on a central axis, and the ovary is unilocular (single-chambered) because septa are absent. Found in a multicarpellary, syncarpous ovary (e.g., *Dianthus*, Primrose).
• Basal: The placenta develops at the very base of the ovary, and a single ovule is attached to it. Found in a unilocular ovary (e.g., Sunflower, Marigold).

The Fruit

The fruit is a distinctive feature of flowering plants, developing specifically after fertilization of the ovary. It is essentially a mature or ripened ovary.

A fruit formed without fertilization of the ovary is called a parthenocarpic fruit (e.g., seedless grapes, bananas). These fruits are typically seedless.

Structure of a Fruit: A fruit generally consists of a wall called the pericarp and one or more seeds.

Pericarp: The pericarp can be thin and dry or thick and fleshy. When fleshy, it is usually differentiated into three layers:

• Epicarp: The outer skin or layer.
• Mesocarp: The middle layer, often fleshy and edible.
• Endocarp: The inner layer, which may be hard and stony or membranous, enclosing the seed(s).

Drupe: A specific type of fleshy fruit that develops from a monocarpellary, superior ovary and is typically one-seeded (Figure 5.17). The pericarp is differentiated into epicarp, mesocarp, and endocarp.

• In Mango, the pericarp is clearly differentiated: a thin epicarp, a fleshy edible mesocarp, and a hard, stony endocarp enclosing the single seed.
• Coconut is also a drupe, but its mesocarp is fibrous rather than fleshy.

The Seed

Seeds develop from the ovules after fertilization.

A seed is generally composed of a seed coat and an embryo.

The embryo is the rudimentary plant within the seed. It consists of:

• A radicle (embryonic root)
• An embryonal axis (the central axis of the embryo)
• One or two cotyledons (embryonic leaves)

Seeds are primarily classified based on the number of cotyledons:

• Monocotyledonous seeds: Have one cotyledon (e.g., Wheat, Maize).
• Dicotyledonous seeds: Have two cotyledons (e.g., Gram, Pea).

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Structure Of A Dicotyledonous Seed

The outermost protective layer of a dicot seed is the seed coat.

The seed coat typically consists of two layers: an outer testa and an inner tegmen.

On the seed coat, there is a scar called the hilum, which marks the point where the developing seed was attached to the fruit via the stalk (funiculus).

Above the hilum, there is a small pore called the micropyle, which was the opening in the ovule wall and facilitates water entry during germination.

Inside the seed coat is the embryo, consisting of the embryonal axis and two cotyledons.

The two cotyledons are often thick and fleshy, storing reserve food material.

The embryonal axis has the radicle (embryonic root) at one end and the plumule (embryonic shoot) at the other end (Figure 5.18).

Based on the presence or absence of endosperm in the mature seed:

• Endospermic (Albuminous) seeds: The endosperm, formed from double fertilization, is present as a food-storing tissue in the mature seed (e.g., Castor).
• Non-endospermous (Exalbuminous) seeds: The endosperm is either absent or completely consumed by the developing embryo during seed development, so it is not present in the mature seed. Food is stored in the cotyledons (e.g., Bean, Gram, Pea).

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Structure Of Monocotyledonous Seed

Monocotyledonous seeds are generally endospermic, meaning they retain endosperm as a food storage tissue (exceptions include orchids which are non-endospermic).

In cereal seeds (like maize), the seed coat is membranous and fused with the fruit wall, forming a single layer.

The endosperm is bulky and serves as the primary food storage tissue.

The endosperm is separated from the embryo by a proteinaceous layer called the aleurone layer.

The embryo in monocot seeds is usually small and located in a groove at one end of the endosperm.

It consists of:

• One large, shield-shaped cotyledon known as the scutellum.
• A short embryonal axis containing the plumule and the radicle.

The plumule and radicle are enclosed within protective sheaths:

• Coleoptile: Sheath covering the plumule.
• Coleorhiza: Sheath covering the radicle.

Semi-Technical Description Of A Typical Flowering Plant

Describing a flowering plant systematically involves using specific morphological features and technical terms. The description should be concise, clear, and follow a particular sequence:

1. Habit: Describe the general form of the plant (e.g., herb, shrub, tree, climber).
2. Vegetative Characters: Describe the roots, stem, and leaves.
3. Floral Characters: Describe the inflorescence and the flower parts (calyx, corolla, androecium, gynoecium).
4. Fruit and Seed: Describe the characteristics of the fruit and seed.
5. Floral Formula and Floral Diagram: Summarize the floral features using standard symbols and a diagram.

The description concludes with a floral formula and a floral diagram, which provide a summarized representation of the flower's characteristics.

Floral Formula: Uses standard symbols to represent the number and arrangement of floral parts, their fusion (cohesion), and their attachment to other whorls (adhesion).

Standard Symbols Used:

Symbol	Meaning
Br	Bracteate (Presence of bracts)
Ebr	Ebracteate (Absence of bracts)
$\textsf{Å}$	Actinomorphic (Radial symmetry)
$\textsf{\%}$	Zygomorphic (Bilateral symmetry)
$\sigma$	Male flower (Unisexual male)
$♀$	Female flower (Unisexual female)
$\textsf{♂♀}$	Bisexual flower (Hermaphrodite)
K	Calyx
C	Corolla
P	Perianth (when K & C are not distinct)
A	Androecium (Stamens)
G	Gynoecium (Carpels)
$\underline{\textsf{G}}$	Ovary Superior (Hypogynous flower)
$\overline{\textsf{G}}$	Ovary Inferior (Epigynous flower)
$\textsf{G}$	Ovary Half Inferior (Perigynous flower)
( )	Fusion or Cohesion (parts united), e.g., K(5) means 5 united sepals.
A line above symbols	Adhesion (parts of different whorls united), e.g., C5 A5 with a line above A means 5 petals are free, and 5 stamens are attached to the petals (epipetalous).
A number subscript	Number of units in a whorl, e.g., C$_5$ means 5 petals. A$_{2+4}$ means stamens arranged in two whorls of 2 and 4.
$\infty$	Indefinite number of units (more than 12)

Floral Diagram: A graphical representation providing information about:

• The number of floral parts.
• Their arrangement in successive whorls.
• The relationship (cohesion and adhesion) between parts within a whorl and between different whorls.

Representation in Diagram:

• The diagram is drawn from the top view of the flower.
• The position of the mother axis (the stem on which the flower is borne) is indicated by a dot placed above the floral diagram.
• Floral whorls are drawn in concentric circles: Calyx (outermost), Corolla, Androecium, and Gynoecium (in the center).
• Fusion is shown by joining the margins of the represented parts. Adhesion is shown by connecting lines between different whorls.

Example Floral Formula and Diagram (Mustard, Family: Brassicaceae):

Floral Formula: Br $\textsf{Å}$ $\textsf{♂♀}$ K$_{2+2}$ C$_4$ A$_{2+4}$ G$_{(2)}$

Interpretation:

• Br: Bracteate (though often omitted if ebracteate)
• $\textsf{Å}$: Actinomorphic (Radial symmetry)
• $\textsf{♂♀}$: Bisexual
• K$_{2+2}$: Calyx with 4 sepals, arranged in two whorls of 2 each, sepals are free (no bracket).
• C$_4$: Corolla with 4 petals, petals are free.
• A$_{2+4}$: Androecium with 6 stamens, arranged in two whorls, 2 in the outer whorl and 4 in the inner whorl, stamens are free.
• G$_{(2)}$: Gynoecium with 2 carpels, carpels are united (syncarpous), ovary is superior (indicated by the underline).

The floral formula and diagram together provide a concise and comprehensive description of a flower's structure.

Description Of Some Important Families

Examining the characteristics of specific plant families helps in understanding the application of morphological descriptions and classification.

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Fabaceae

Earlier Name: Papilionoideae (considered a subfamily of Leguminosae).

Distribution: Worldwide.

Vegetative Characters:

• Habit: Includes trees, shrubs, and herbs.
• Root: Presence of root nodules containing nitrogen-fixing bacteria.
• Stem: Erect or climbing.
• Leaves: Typically alternate. Can be pinnately compound or simple. Leaf base is often swollen (pulvinate). Stipules are present (stipulate). Venation is reticulate.

Floral Characters:

• Inflorescence: Racemose.
• Flower: Bisexual and zygomorphic ($\textsf{\%}$).
• Calyx: 5 sepals, united (gamosepalous). Aestivation is valvate or imbricate.
• Corolla: 5 petals, free (polypetalous). Exhibiting papilionaceous (vexillary) aestivation: a large standard petal, two lateral wing petals, and two anterior petals forming a keel.
• Androecium: 10 stamens, usually arranged in two bundles (diadelphous), $9+1$ arrangement is common (9 united, 1 free). Anthers are dithecous (two pollen sacs in each lobe).
• Gynoecium: Ovary superior ($\underline{\textsf{G}}$), composed of a single carpel (monocarpellary), single-chambered (unilocular) with many ovules. Style is single.

Fruit: A legume (pod) that typically splits along two sutures.

Seed: One to many, non-endospermic.

Floral Formula: $\textsf{\%}$ $\textsf{♂♀}$ K$_{(5)}$ C$_{1+2+(2)}$ A$_{(9)+1}$ $\underline{\textsf{G}}_1$

Economic Importance:

• Pulses: Gram, Arhar (Pigeon pea), Sem (Broad bean), Moong (Green gram), Soyabean.
• Edible oil: Soyabean, Groundnut.
• Dye: *Indigofera*.
• Fibres: Sunhemp.
• Fodder: *Sesbania*, *Trifolium* (Clover).
• Ornamentals: Lupin, Sweet pea.
• Medicine: Muliathi (Liquorice).

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Solanaceae

Common Name: 'Potato family'.

Distribution: Widely distributed in tropical, subtropical, and temperate zones.

Vegetative Characters:

• Habit: Mostly herbs, some shrubs, rarely small trees.
• Stem: Herbaceous (rarely woody), aerial, erect, cylindrical, branched, solid or hollow, may be hairy or smooth (glabrous). Underground stems are modified for storage in potato (*Solanum tuberosum*).
• Leaves: Alternate, simple, rarely pinnately compound. Exstipulate (stipules absent). Venation is reticulate.

Floral Characters:

• Inflorescence: Solitary (single flower), axillary, or cymose (*Solanum*).
• Flower: Bisexual and actinomorphic ($\textsf{Å}$).
• Calyx: 5 sepals, united (gamosepalous), persistent (remain with the fruit). Aestivation is valvate.
• Corolla: 5 petals, united (gamopetalous). Aestivation is valvate.
• Androecium: 5 stamens, epipetalous (attached to the petals).
• Gynoecium: Bicarpellary (two carpels), united (syncarpous). Ovary is superior ($\underline{\textsf{G}}$), typically bilocular (two-chambered), but can be unilocular in some due to false septum. Carpels are often placed obliquely (at an angle). Placenta is swollen with many ovules. Placentation is axile.

Fruits: Berry or Capsule.

Seeds: Many, endospermous.

Floral Formula: $\textsf{Br}$ (often absent, so Ebr is implied) $\textsf{Å}$ $\textsf{♂♀}}$ K$_{(5)}$ C$_{(5)}$ A$_5^{\text{epipetalous}}$ $\underline{\textsf{G}}_{(2)}$

Economic Importance:

• Food: Tomato, Brinjal (Eggplant), Potato.
• Spice: Chilli.
• Medicine: Belladonna (*Atropa belladonna*), Ashwagandha (*Withania somnifera*).
• Fumigatory: Tobacco (*Nicotiana tabacum*).
• Ornamentals: Petunia.

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Liliaceae

Common Name: 'Lily family'.

Characteristic Group: A representative family of monocotyledonous plants.

Distribution: World wide.

Vegetative Characters:

• Habit: Perennial herbs.
• Underground Storage: Possess underground structures like bulbs, corms, or rhizomes.
• Leaves: Mostly basal (arising from the base of the stem), alternate, linear. Exstipulate (stipules absent). Venation is parallel, characteristic of monocots.

Floral Characters:

• Inflorescence: Solitary (single flower), cymose, often arranged in umbellate clusters (like an umbrella).
• Flower: Bisexual and actinomorphic ($\textsf{Å}$).
• Perianth: Consists of 6 units called tepals (since calyx and corolla are not distinct). Tepals are usually arranged in two whorls of 3 each (3+3), often united into a tube. Aestivation is valvate.
• Androecium: 6 stamens, arranged in two whorls of 3 each (3+3). Stamens are epitepalous (attached to the tepals).
• Gynoecium: Tricarpellary (three carpels), united (syncarpous). Ovary is superior ($\underline{\textsf{G}}$), trilocular (three-chambered) with many ovules. Placentation is axile.

Fruit: Usually a capsule, rarely a berry.

Seed: Endospermous.

Floral Formula: Br $\textsf{Å}$ $\textsf{♂♀}}$ P$_{(3+3)}$ A$_{3+3}^{\text{epitepalous}}$ $\underline{\textsf{G}}_{(3)}$

Economic Importance:

• Ornamentals: Tulip, *Gloriosa*.
• Medicine: Aloe (*Aloe vera*).
• Vegetables: Asparagus (*Asparagus officinalis*).
• Source of Colchicine (an alkaloid used in genetics): *Colchicum autumnale*.

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