Class 11 Biology Morphology of Flowering Plants Notes for NEET
1. 🌱 Morphology of Flowering Plants – Introduction
The variety in the structure of higher plants is truly fascinating. Even though flowering plants, or angiosperms, show a huge diversity in their external appearance or morphology, they all have some common features: roots, stems, leaves, flowers, and fruits. In earlier chapters, we studied how plants are classified based on their morphology and other characteristics. To properly classify plants and understand any higher plant—or any living organism—we need to know standard technical terms and definitions. It is also important to understand the variations in plant parts, which often occur as adaptations to their environment, such as adaptations for different habitats, protection, climbing, or storage. For example, if you pull out any common weed, you will notice that it has roots, stems, and leaves, and sometimes flowers and fruits as well. The part of the plant that grows underground is called the root system, while the part that grows above the ground is called the shoot system. These systems help the plant survive, grow, and reproduce efficiently in its environment.
🔷 What is Morphology ?
Morphology is the branch of biology that deals with the study of the external form, structure, and appearance of plants. The term “morphology” comes from two Greek words: “morpho” meaning form, and “logy” meaning study. In simple words, it means the study of outer features of living organisms, especially in the case of plants. This includes the study of parts like roots, stems, leaves, flowers, fruits, and seeds – how they look, how they are arranged, and how they vary from plant to plant. Morphology helps us understand how each part contributes to the function and survival of the plant in its environment.
🔷 Why is Morphology Important ?
Morphology is not just about knowing the parts of a plant. It is extremely useful in many areas of biology, taxonomy, agriculture, and medicine. One of its most important uses is in the identification of plants. For example, by observing leaf type, root system, and flower symmetry, we can often guess which family or species a plant belongs to. This is especially helpful for field biologists and botanists.
In addition, morphology is the basis of plant classification. Taxonomists divide plants into families, genera, and species using morphological characters. For example, members of the Fabaceae family show a unique flower structure (papilionaceous corolla), which helps us identify them easily. Thus, morphology supports the entire structure of botanical classification and naming (nomenclature).
2. Root – Structure and Functions
In most dicotyledonous plants, the radicle, which is the first root to grow from a seed, elongates directly into the soil to form the primary root. This primary root gives rise to lateral roots of different orders, called secondary, tertiary roots, and so on. Together, the primary root and all its branches form what is known as the tap root system, which is clearly seen in plants like mustard. In monocotyledonous plants, the primary root does not last long and is quickly replaced by a large number of roots that emerge from the base of the stem, forming a fibrous root system, as seen in wheat. Some plants, such as grasses, Monstera, and banyan trees, develop roots from parts of the plant other than the radicle; these are called adventitious roots. The root system has several important functions: it absorbs water and minerals from the soil, provides firm anchorage to the plant, stores reserve food materials, and also produces plant growth regulators that help in the overall growth and development of the plant.
Area Where Root Is Present
The tip of a root is covered by a thimble-shaped structure called the root cap, which protects the delicate growing tip as it pushes through the soil. Just above the root cap is the region of meristematic activity, where cells are very small, thin-walled, and filled with dense protoplasm. These cells divide continuously, producing new cells. The cells just above this meristematic region start to elongate and enlarge rapidly, which makes the root grow in length; this part is called the region of elongation. As the cells in this zone continue to grow, they gradually mature and differentiate into specific types of cells, forming the region of maturation. From this mature region, some epidermal cells develop into tiny, thread-like structures called root hairs. These root hairs play an important role in absorbing water and minerals from the soil, helping the plant to survive and grow efficiently.
Root Modifications – Types and Functions
In some plants, roots change their shape and structure and become modified to perform functions other than just absorption and conduction of water and minerals. These modified roots help in support, food storage, and respiration. For example, the tap roots of carrot and turnip, and the adventitious roots of sweet potato become swollen to store food. Some roots also help in supporting the plant. For instance, the prop roots of a banyan tree hold up its heavy branches. Similarly, in plants like maize and sugarcane, stilt roots emerge from the lower nodes of the stem to provide extra support. In swampy areas, some plants like Rhizophora produce roots that grow vertically upwards from the soil; these are called pneumatophores, and they help the plant get oxygen for respiration in waterlogged conditions.
3. All About The Stem Of Plant
A stem is the ascending part of a plant’s axis that bears branches, leaves, flowers, and fruits. It develops from the plumule of the embryo in a germinating seed. The stem has nodes and internodes. Nodes are the regions where leaves grow, while internodes are the portions between two nodes. The stem also bears buds, which may be terminal or axillary. When young, stems are usually green, but as they mature, they often become woody and dark brown. The main functions of the stem include supporting and spreading out branches that hold leaves, flowers, and fruits, as well as conducting water, minerals, and photosynthates throughout the plant. Some stems are also modified to perform additional functions such as food storage, support, protection, and vegetative propagation.
How Stem Is Modified To Perform Specific Functions
Not all stems look like the typical upright structure we usually expect. Many stems are modified to perform special functions. Some underground stems like potato, ginger, turmeric, zaminkand, and Colocasia are swollen to store food and also act as organs of perennation, helping plants survive unfavorable conditions. Some stems develop tendrils from axillary buds; these are slender, spirally coiled, and help plants climb, as seen in cucumber, pumpkin, watermelon, and grapevine. Axillary buds may also turn into thorns, which are woody, pointed, and protect plants from grazing animals, examples being Citrus and Bougainvillea. In plants from arid regions, stems may be modified into flattened forms like Opuntia or fleshy cylindrical forms like Euphorbia; these stems contain chlorophyll and carry out photosynthesis. Some underground stems, like those of grass and strawberry, spread horizontally and help produce new plants when older parts die. In plants like mint and jasmine, a slender lateral branch grows from the base of the main stem, rises above ground, then arches down to touch the soil. In aquatic plants like Pistia and Eichhornia, a lateral branch with short internodes develops a rosette of leaves and a tuft of roots. In plants like banana, pineapple, and Chrysanthemum, lateral branches arise from the basal underground stem, grow horizontally, and then come obliquely upward, forming new leafy shoots.
3. Leaf – Structure and Functions
A leaf is a lateral, usually flattened structure that grows on the stem at a node and usually has a bud in its axil, which can later grow into a branch. Leaves develop from the shoot apical meristem and are arranged in an acropetal order. They are the most important vegetative organs for photosynthesis. A typical leaf has three main parts: the leaf base, petiole, and lamina or leaf blade. The leaf base attaches the leaf to the stem and may have two small lateral stipules. In monocotyledons, the leaf base often expands into a sheath that partially or completely covers the stem. In some leguminous plants, the leaf base becomes swollen, forming a pulvinus. The petiole holds the lamina in the light and, when long and flexible, allows the leaf to flutter in the wind, which helps in cooling and brings fresh air to the leaf surface. The lamina is the green, expanded part of the leaf with veins and veinlets. Usually, there is a prominent central vein called the midrib. Veins provide rigidity to the leaf and act as channels for transporting water, minerals, and food. The shape, margin, apex, surface, and extent of incisions of the lamina vary among different leaves, giving them diverse forms and adaptations.
Leaf Venation – Patterns and Types
The arrangement of veins and veinlets in the lamina of a leaf is called venation. When the veinlets form a network, it is called reticulate venation. On the other hand, when the veins run parallel to each other along the lamina, it is called parallel venation. Generally, dicotyledonous plants have reticulate venation, while most monocotyledons exhibit parallel venation. This pattern of venation helps in providing strength, support, and efficient transport of water, minerals, and food throughout the leaf.
Phyllotaxy – Leaf Arrangement on Stem
Phyllotaxy is the pattern of arrangement of leaves on a stem or branch. There are three main types of phyllotaxy: alternate, opposite, and whorled. In alternate phyllotaxy, a single leaf grows at each node in an alternate manner, as seen in plants like China rose, mustard, and sunflower. In opposite phyllotaxy, two leaves grow at each node and lie opposite to each other, as seen in Calotropis and guava. When more than two leaves arise at a node and form a whorl, it is called whorled phyllotaxy, as in Alstonia. This arrangement helps the plant maximize light capture for photosynthesis and efficient growth.
Leaf Types – Classification and Example
A leaf is called simple when its lamina is entire or the incisions in it do not reach the midrib. If the incisions go all the way to the midrib, breaking the lamina into multiple leaflets, it is called a compound leaf. In both simple and compound leaves, a bud is present in the axil of the petiole, but in a compound leaf, there is no bud in the axil of individual leaflets. Compound leaves are of two types: pinnately compound and palmately compound. In a pinnately compound leaf, several leaflets are arranged along a common axis called the rachis, which represents the midrib of the leaf, as seen in neem. In palmately compound leaves, the leaflets are attached at a common point, usually at the tip of the petiole, as in silk cotton. These arrangements allow leaves to capture sunlight efficiently and increase the surface area for photosynthesis.
Leaf Modifications – Types and Functions
Leaves are often modified to perform functions other than photosynthesis. Some leaves become tendrils, which help plants climb, as seen in peas. In other plants, leaves are modified into spines for protection, like in cacti. Some fleshy leaves, such as in onion and garlic, are modified to store food. In certain plants, like Australian acacia, the leaves are small and short-lived, while the petioles expand, turn green, and take over the function of food synthesis. Some insectivorous plants, such as the pitcher plant and Venus flytrap, have specialized leaves to trap and digest insects, showing the amazing adaptability of leaves in different plants.
4. Inflorescence – Types and Arrangement of Flowers
A flower is a modified shoot in which the shoot apical meristem transforms into a floral meristem. In flowers, the internodes do not elongate, causing the axis to become condensed, and the apex produces floral appendages at different nodes instead of leaves. When a shoot tip becomes a flower, it is usually solitary. The way flowers are arranged on the floral axis is called inflorescence. There are two main types of inflorescence: racemose and cymose, depending on whether the apex continues to grow or ends as a flower. In racemose inflorescence, the main axis keeps growing and flowers are arranged laterally in an acropetal succession, meaning the youngest flowers are at the top. In cymose inflorescence, the main axis ends in a flower, so growth is limited, and the flowers develop in a basipetal order, with the older flowers at the top and younger flowers below. This arrangement ensures proper flower display for pollination and reproduction.
5. Flower – Structure and Parts
A flower is the reproductive unit of angiosperms and is responsible for sexual reproduction. A typical flower has four whorls arranged on the swollen tip of the stalk or pedicel, called the thalamus or receptacle. These whorls are calyx, corolla, androecium, and gynoecium. Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs. In some flowers like lily, the calyx and corolla are not distinct and together called perianth. A flower with both androecium and gynoecium is bisexual, while one having only stamens or only carpels is unisexual. Flowers also show symmetry. If a flower can be divided into two equal halves along any radial plane, it is actinomorphic (radial symmetry), e.g., mustard, datura, chilli. If it can be divided into two similar halves along only one vertical plane, it is zygomorphic (bilateral symmetry), e.g., pea, gulmohur, bean, Cassia. If it cannot be divided into two similar halves along any plane, it is asymmetric, e.g., canna. Flowers can also be trimerous, tetramerous, or pentamerous, when floral parts are in multiples of 3, 4, or 5, respectively. Flowers with bracts (small reduced leaves at the base) are bracteate, while those without are ebracteate.
Based on the position of calyx, corolla, and androecium relative to the ovary, flowers are classified as hypogynous, perigynous, and epigynous. In hypogynous flowers, the gynoecium is at the top and other parts lie below, making the ovary superior, e.g., mustard, china rose, brinjal. In perigynous flowers, the gynoecium is central and other parts are at the rim of the thalamus, making the ovary half-inferior, e.g., plum, rose, peach. In epigynous flowers, the thalamus margin grows upward, enclosing the ovary and fusing with it, while other parts arise above the ovary, making the ovary inferior, e.g., guava, cucumber, and sunflower ray florets
Flower Parts – Structure and Functions
A typical flower is made up of four main floral whorls, which are the calyx, corolla, androecium, and gynoecium. The calyx is the outermost whorl, and its parts are called sepals. Sepals are usually green and leaf-like, and their main job is to protect the flower while it is still a bud. Sepals can either be free from each other (polysepalous) or fused together (gamosepalous). The next whorl, the corolla, is made of petals. Petals are often brightly colored to attract insects for pollination. Like sepals, petals may be free (polypetalous) or fused (gamopetalous), and their shape can vary widely, appearing tubular, bell-shaped, funnel-shaped, or wheel-shaped. The way sepals or petals are arranged in a bud is called aestivation. For example, in valvate aestivation, the margins of petals or sepals just touch each other without overlapping, as in Calotropis. In twisted aestivation, one margin overlaps the next, as seen in China rose, lady’s finger, and cotton. Imbricate aestivation has overlapping margins but without a fixed pattern, like in Cassia and Gulmohur. A special type, vexillary or papilionaceous aestivation, occurs in pea and bean flowers, where the largest petal (standard) overlaps the two side petals (wings), which in turn overlap the two smallest front petals (keel).
The androecium represents the male reproductive part of a flower and is made up of stamens. Each stamen consists of a filament (stalk) and an anther, which usually has two lobes, each containing two pollen sacs where pollen grains are produced. Some stamens are sterile and are called staminodes. Stamens may either be free (polyandrous) or fused in different ways. For instance, when stamens attach to petals, they are epipetalous, as in brinjal, or epiphyllous when attached to the perianth, as in lily. Fused stamens can form one bundle (monadelphous) as in China rose, two bundles (diadelphous) as in pea, or more than two bundles (polyadelphous) as in citrus. There may also be variation in filament length within a single flower, as seen in Salvia and mustard.
The gynoecium is the female reproductive part and is composed of one or more carpels. Each carpel has three main parts: the stigma, style, and ovary. The ovary is the enlarged base, the style is a tube connecting ovary to stigma, and the stigma is the tip that receives pollen grains. Each ovary contains ovules, which are attached to a placenta, a cushion-like structure. Carpels may be free (apocarpous), as in lotus and rose, or fused (syncarpous), as in mustard and tomato. After fertilization, ovules develop into seeds and the ovary becomes a fruit. The arrangement of ovules inside the ovary is called placentation, which can be marginal, axile, parietal, basal, or free central. In marginal placentation, ovules grow along a ridge at the ventral suture, forming two rows, as in pea. Axile placentation occurs in a multilocular ovary with ovules on the central axis, as in China rose, tomato, and lemon. In parietal placentation, ovules grow on the inner wall of the ovary, forming a false septum, like in mustard. Free central placentation has ovules on the central axis without septa, as in Dianthus and Primrose. Basal placentation has a single ovule attached at the base of ovary, as in sunflower and marigold.
6. Fruit – Types and Development
A fruit is a very important feature of flowering plants and is basically a mature or ripened ovary that forms after fertilization. Sometimes, a fruit can develop without fertilization, and such fruits are called parthenocarpic fruits. A typical fruit is made up of a wall called pericarp and seeds inside it. The pericarp can be either dry or fleshy. When the pericarp is thick and fleshy, it is divided into three layers: the outer layer called epicarp, the middle layer called mesocarp, and the inner layer called endocarp. A common example of such fruits is a drupe, like in mango and coconut. These drupes develop from a single carpel (monocarpellary) and a superior ovary, and they usually have one seed. In mango, the epicarp is the thin outer skin, the mesocarp is the fleshy and edible part, and the endocarp is hard and stony, protecting the seed inside. In coconut, which is also a drupe, the mesocarp is fibrous instead of fleshy, giving it a different texture but the same basic structure.
7. Seed – Structure and Types
After fertilization, the ovules of a flower develop into seeds, which are the next generation of plants. A seed has two main parts: the seed coat and the embryo. The seed coat is the protective outer layer that shields the embryo from damage and drying. The embryo is the young plant inside the seed and consists of three main parts: the radicle, which develops into the root; the embryonal axis, which forms the stem and future branches; and the cotyledons, which are the seed leaves that store food for the growing plant. Depending on the type of plant, a seed may have one cotyledon (called monocotyledonous, as in wheat and maize) or two cotyledons (called dicotyledonous, as in gram and pea). These cotyledons provide the initial nourishment for the seedling until it can start photosynthesis on its own.
Dicot Seed – Structure and Parts
The outermost layer of a seed is called the seed coat, which acts as a protective covering for the embryo inside. The seed coat itself has two layers: the outer layer is called the testa, and the inner layer is called the tegmen. On the seed coat, there is a small scar known as the hilum, which shows where the seed was attached to the fruit during its development. Just above the hilum is a tiny opening called the micropyle, which allows water to enter during germination. Inside the seed coat lies the embryo, which is made up of the embryonal axis and cotyledons. The cotyledons are often fleshy and packed with reserve food to support the seedling after germination. At the two ends of the embryonal axis are the radicle, which develops into the root, and the plumule, which develops into the shoot. Some seeds, like castor, have a special tissue called endosperm, which stores food formed as a result of double fertilization, and these are called endospermic seeds. In contrast, seeds of plants like bean, gram, and pea do not have endosperm in their mature form, and these are called non-endospermic seeds.
Monocot Seed – Structure and Parts
Most monocotyledonous seeds have endosperm, which stores food for the growing embryo, but some, like in orchids, do not have endosperm and are non-endospermic. In cereal seeds such as maize, the seed coat is very thin, membranous, and often fused with the fruit wall. The endosperm is large and serves as the main food reserve. The embryo in such seeds is relatively small and located in a groove at one end of the endosperm. The embryo contains one large, shield-shaped cotyledon called the scutellum and a short embryonal axis that includes a plumule (future shoot) and a radicle (future root). The plumule and radicle are protected by sheaths called the coleoptile and coleorhiza, respectively, which help in protecting the young seedling as it emerges from the seed during germination.
8. Typical Flowering Plant – Semi-Technical Description
When describing a flowering plant, scientists use various morphological features to make the description brief, clear, and scientific. The description usually follows a sequence, starting with the habit of the plant, followed by vegetative characters like roots, stem, and leaves, and then the floral characters, including inflorescence and the flower parts. After describing these parts, a floral diagram and a floral formula are presented to give a complete picture of the flower. The floral formula uses symbols to represent different parts: Br for bract, K for calyx, C for corolla, P for perianth, A for androecium, and G for gynoecium. The formula also shows whether the ovary is superior or inferior, the sexual nature of the plant (male, female, or bisexual), and the symmetry of the flower (⊕ for radially symmetrical or actinomorphic, and a different symbol for bilaterally symmetrical or zygomorphic). Fusion of similar parts is shown by brackets, while adhesion between different whorls is shown by a line above the symbols.
A floral diagram complements the formula by showing the number of parts, their arrangement, and how they are related to each other. The mother axis of the flower is represented by a dot at the top of the diagram. The whorls are drawn in order: calyx on the outside, followed by corolla, androecium, and finally gynoecium at the center. Both the floral formula and diagram give information about cohesion (fusion within a whorl) and adhesion (fusion between whorls), making them very useful for identifying and comparing plants. For example, in the Brassicaceae family, both the diagram and formula clearly represent these features.
10. Important Plant Families – Description and Characteristics
Solanaceae Family – Key Features and Examples
The Solanaceae family, commonly called the “potato family”, is a large family widely found in the tropics, subtropics, and even temperate regions. Plants in this family are mostly herbs, some shrubs, and rarely small trees. Their stems are usually herbaceous, sometimes woody, and can be erect, cylindrical, branched, either solid or hollow, hairy or smooth (glabrous). Some plants, like potato (Solanum tuberosum), have underground stems. The leaves are mostly alternate, simple, rarely pinnately compound, without stipules, and have reticulate venation. The inflorescence can be solitary, axillary, or cymose, as seen in Solanum. The flowers are bisexual and actinomorphic (radially symmetrical). The calyx has five sepals, which are fused (gamosepalous), persistent, with valvate aestivation. The corolla has five petals, also fused, with valvate aestivation. The androecium consists of five stamens that are epipetalous (attached to petals). The gynoecium is bicarpellary, obligately placed, fused (syncarpous), with a superior ovary, bilocular, and axile placentation with many ovules. The fruits are usually berries or capsules, and the seeds are numerous and endospermic. Its floral formula is represented as: ⊕ K(5) C(5) A5 G(2).
The economic importance of the Solanaceae family is very high. Many plants provide food, such as tomato, brinjal, and potato; spices like chilli; medicinal plants like belladonna and ashwagandha; fumigatory products such as tobacco; and ornamentals like petunia. This family is therefore important for agriculture, medicine, and horticulture.
Fabaceae Family – Key Features and Examples
The Fabaceae family, which was earlier called Papilionoideae, is a widely distributed family found all over the world. Plants in this family can be trees, shrubs, or herbs, and their roots often have root nodules that help in nitrogen fixation. The stem may be erect or climbing, and the leaves are usually alternate, sometimes pinnately compound or simple, with a pulvinate base, stipules, and reticulate venation. The inflorescence is generally racemose, and the flowers are bisexual and zygomorphic (bilaterally symmetrical). The calyx has five sepals that are fused (gamosepalous) with valvate or imbricate aestivation, while the corolla has five petals, which are free (polypetalous) and papilionaceous, consisting of a posterior standard, two lateral wings, and two anterior petals forming a keel that encloses the stamens and pistil, with vexillary aestivation. The androecium has ten stamens, arranged in two bundles (diadelphous), with dithecous anthers. The gynoecium is superior, monocarpellary, unilocular, with many ovules and a single style. The fruit is a legume, and the seeds are one to many and non-endospermic. Its floral formula can be represented as: % K(5) C1+2+(2) A(9)+1 G1.
The economic importance of this family is very high. Many members are sources of pulses like gram, arhar, sem, moong, and soybean; edible oils such as soybean and groundnut; natural dyes like Indigofera; fibers such as sunhemp; fodder plants like Sesbania and Trifolium; ornamental plants like lupin and sweet pea; and medicinal plants such as muliathi. This family plays a very important role in agriculture, industry, and medicine.
Liliaceae Family – Key Features and Examples
The Liliaceae family, commonly called the “Lily family”, is a typical example of monocotyledonous plants and is found worldwide. Plants in this family are mostly perennial herbs with underground bulbs, corms, or rhizomes, which help them survive adverse conditions. The leaves are usually basal, alternate, and linear, without stipules, and have parallel venation, which is characteristic of monocots. The inflorescence can be solitary or cymose, often forming umbellate clusters. The flowers are bisexual and actinomorphic (radially symmetrical). The perianth consists of six tepals arranged in two whorls of 3+3, which are often fused to form a tube, with valvate aestivation. The androecium has six stamens arranged in 3+3 and attached to the tepals (epitepalous). The gynoecium is tricarpellary and syncarpous, with a superior ovary, trilocular, containing many ovules, and exhibiting axile placentation. The fruit is usually a capsule, rarely a berry, and the seeds are endospermic. The floral formula is: Br ⊕ P(3+3) A3+3 G(3).
The economic importance of the Liliaceae family is significant. Many members are valued as ornamental plants, such as tulip and Gloriosa; some provide medicinal products, like Aloe; some are used as vegetables, like Asparagus; and others produce important compounds, such as colchicine from Colchicum autumnale, which is used in medicine and research.
Conclusion
The Fabaceae, Solanaceae, and Liliaceae families hold major importance in the plant kingdom and human life. These families differ in floral symmetry, ovary structure, stamen arrangement, and fruit types, which are essential for their identification and classification. The semi-technical descriptions, along with floral formulas and diagrams, help students and botanists in understanding plant diversity systematically. From food and medicine to ornamentals and industrial uses, plants from these families contribute significantly to agriculture and the economy. Mastering the structure, symbols, and examples of these families is crucial for excelling in NEET and other biology exams.
10. Chapter Overview – Key Points and Highlights
Flowering plants show an incredible variation in their shape, size, structure, mode of nutrition, lifespan, habit, and habitat. They have well-developed root and shoot systems. The root system can be either a taproot or fibrous root system. Generally, dicotyledonous plants have taproots, while monocotyledonous plants have fibrous roots. In some plants, roots get modified for food storage, mechanical support, or respiration. The shoot system is made up of stem, leaves, flowers, and fruits. Stems can be recognized by the presence of nodes and internodes, multicellular hairs, and their positive phototropism. Stems may also get modified for food storage, vegetative propagation, or protection under various conditions. Leaves, which are lateral outgrowths of the stem at the nodes, are usually green to perform photosynthesis. Leaves vary widely in shape, size, margin, apex, and blade incision, and they can also get modified into tendrils for climbing or spines for protection.
Flowers are modified shoots specialized for sexual reproduction and are arranged in different types of inflorescences. Flowers vary greatly in structure, symmetry, position of the ovary, and arrangement of petals, sepals, and ovules. After fertilization, the ovary develops into a fruit and the ovules into seeds, which can be monocotyledonous or dicotyledonous. Seeds also differ in shape, size, and viability period. The floral characteristics are very important as they form the basis for classification and identification of flowering plants. To describe a flowering plant scientifically, a definite sequence is followed, often summarized using floral diagrams and floral formulas, which provide a quick and clear representation of the flower’s structure.