Morphology of Flowering Plants — NEET notes

Root System — The Underground Anchor & Absorber

Roots anchor the plant, absorb water and minerals, and store food. Dicots have a taproot system (one main root + branches), monocots have a fibrous root system (many equal-sized roots). Roots can be modified for storage, support, respiration, and even parasitism.

Taproot vs Fibrous Root

The two fundamental root systems differ in origin, structure, and the plant groups they belong to.

The radicle (embryonic root) of a germinating seed develops into the primary root. In dicots, this primary root grows deep and persists as the taproot, with smaller lateral roots branching off it. In monocots, the primary root is short-lived — instead, roots arise from the base of the stem as a cluster of similarly-sized adventitious roots, forming the fibrous root system.

Regions of the Root Tip

A root tip has four distinct zones from the tip upward, each with a specific function in root growth.

If you slice a root tip longitudinally, you'll see four zones from bottom to top:

• Root cap — thimble-like covering at the very tip. Protects the tender growing point as the root pushes through soil. Cells are continuously worn away and replaced
• Region of meristematic activity — just above the root cap. Cells here divide rapidly (mitosis). This is the growth engine of the root
• Region of elongation — cells from the meristem elongate here, pushing the root deeper into the soil. Cells are no longer dividing but are increasing in size
• Region of maturation (differentiation) — cells differentiate into specialized tissues. Root hairs appear here — thin tubular extensions of epidermal cells that massively increase surface area for water absorption

Root Modifications

Roots modify their structure for functions beyond anchorage and absorption — storage of food, mechanical support, gaseous exchange, and even stealing nutrients from host plants.

Roots are versatile. When a plant needs to store food, breathe in waterlogged soil, cling to a wall, or climb a support — the root modifies its shape and function accordingly.

• Storage roots (taproot modifications): Fusiform (radish — spindle-shaped), Conical (carrot — broad top, tapers down), Napiform (turnip — spherical top, narrow base). Sweet potato stores food in adventitious roots, not taproot
• Prop roots (stilt roots): Grow down from branches into the soil for support. Example: Banyan tree — those hanging 'pillars' are prop roots. Maize has stilt roots from lower stem nodes
• Pneumatophores: Grow vertically upward out of waterlogged soil to absorb oxygen. Found in mangrove plants like *Rhizophora* and *Avicennia*. They have small pores (lenticels) for gas exchange
• Parasitic roots (haustoria): Modified roots of parasitic plants that penetrate the host to absorb water/nutrients. Example: *Cuscuta* (dodder/amarbel)
• Climbing roots: Help plants climb walls or tree trunks. Example: Money plant, betel (*Piper betle*)
• Nodular roots: Harbour nitrogen-fixing bacteria (*Rhizobium*). Example: Leguminous plants (pea, bean)

Quick recall

Sweet potato stores food in which type of root — taproot or adventitious?

Adventitious roots. Sweet potato's storage roots arise from the stem, not from the radicle. Contrast with carrot and radish which are taproot modifications.

The Stem — Above-Ground Axis & Master of Disguise

The stem is the ascending axis bearing branches, leaves, flowers, and fruits. It develops from the plumule of the embryo. Stems are modified into an astonishing variety of forms — underground (rhizome, tuber, bulb, corm), sub-aerial (runner, stolon, offset, sucker), and aerial (thorns, tendrils, phylloclades).

Stem Characteristics

The stem bears leaves at nodes, has internodes between them, and grows toward light. These features distinguish it from roots.

The stem develops from the plumule of the embryo. It is the ascending axis of the plant, bearing nodes (points where leaves attach) and internodes (stretches between nodes). The angle between the stem and a leaf is called the axil, and a bud in the axil is the axillary bud — this can grow into a branch.

• Node = point of leaf attachment. Internode = region between two nodes
• Terminal bud (at stem apex) → upward growth. Axillary buds → lateral branches, flowers
• Young stems are usually green and photosynthetic. Older stems become woody (secondary growth)
• Stem is positively phototropic (grows toward light) and negatively geotropic (grows away from gravity)
• Main functions: support, transport of water/nutrients, storage, vegetative propagation

Underground Stem Modifications

Some stems grow underground and get mistaken for roots. They store food, survive unfavorable seasons, and reproduce vegetatively.

These stems grow below the soil and store food. They survive winter/drought when the above-ground parts die. Key rule: they all have nodes, internodes, and buds — which roots don't.

• Rhizome — horizontal underground stem with nodes and internodes. Grows horizontally. Examples: ginger, turmeric, banana. Tip: peel ginger and see the ring-like nodes
• Tuber — swollen tip of an underground stem branch (stolon). Has eyes = axillary buds at nodes. Example: potato. NOT a root — has nodes!
• Bulb — shortened disc-shaped stem surrounded by fleshy scale leaves. The leaves store food, not the stem itself. Examples: onion, garlic. Cut an onion vertically — the tiny disc at the bottom is the actual stem
• Corm — vertical underground stem, swollen with stored food. Has circular nodes (rings) and dry scale leaves. Examples: colocasia (arbi), saffron (*Crocus*), *Amorphophallus*

Sub-Aerial Stems

These stems grow partly along or just below the soil surface, enabling vegetative propagation — the plant spreads by sending out horizontal stems that root at nodes.

Sub-aerial stems spread horizontally along the ground surface or just beneath it. They touch the soil at intervals, develop roots at nodes, and create new plants — enabling vegetative reproduction without seeds.

• Runner — creeps along the soil surface, roots at every node. Example: grass, *Cynodon* (doob grass), strawberry. Stays on the surface
• Stolon — similar to runner but grows underground or arches above ground before touching down. Example: *Fragaria* (strawberry — also called runner sometimes), jasmine, *Mentha*
• Offset — thick, short runner found in aquatic plants. Produces a rosette of leaves at each node. Example: water hyacinth (*Eichhornia*), *Pistia*
• Sucker — grows obliquely upward from underground stem, then emerges. Creates a new plant near the parent. Example: *Chrysanthemum*, banana, *Mentha*

Aerial Stem Modifications

Above-ground stems modify into thorns for protection, tendrils for climbing, and flattened green structures (phylloclades) for photosynthesis in desert plants.

When the environment demands it, stems above ground modify their form for defense, climbing, or photosynthesis.

• Stem thorns — axillary buds modified into sharp, pointed structures for defense. Example: *Citrus*, *Bougainvillea*. Note: stem thorns arise from axillary positions (unlike leaf spines)
• Stem tendrils — thin, wiry, coiling structures for climbing. Arise from axillary buds. Examples: cucumber, pumpkin, watermelon, grapevine (*Vitis*), passion flower
• Phylloclades — flattened, green, leaf-like stems that perform photosynthesis. Found in xerophytes (desert plants) where leaves are reduced to spines to minimize water loss. Examples: *Opuntia* (prickly pear cactus), *Casuarina*, *Euphorbia*
• Cladodes — short phylloclades with limited growth (1-2 internodes). Example: *Asparagus*
• Bulbils — fleshy buds that detach and grow into new plants. Example: *Agave*, *Dioscorea* (yam)

Quick recall

How do you distinguish stem thorns from leaf spines?

Stem thorns arise from axillary buds (e.g., *Citrus*, *Bougainvillea*). Leaf spines are modified leaves arising at the node itself (e.g., *Opuntia* spines are modified leaves). Stem thorns may bear leaves; leaf spines never do.

The Leaf — The Solar Panel of the Plant

Leaves are the primary photosynthetic organs, developing at nodes and having a flat blade (lamina) for maximum light capture. They vary in type (simple vs compound), venation (reticulate vs parallel), and arrangement (phyllotaxy). Leaves modify into tendrils, spines, storage organs, pitchers, and more.

Parts of a Leaf

A typical leaf has three main parts: leaf base, petiole (stalk), and lamina (blade). Some leaves have additional structures called stipules.

A typical leaf consists of: - Leaf base — attaches the leaf to the stem node. In monocots, the leaf base expands into a sheath that wraps around the stem (e.g., grass) - Petiole — the stalk connecting the leaf base to the lamina. Holds the lamina away from the stem for better light exposure. Leaves without petioles are called sessile - Lamina (blade) — the flat, green, expanded part. Has a midrib running through the center with veins branching out

• Petiolate leaf = has a petiole (e.g., mango). Sessile leaf = no petiole, directly attached (e.g., maize)
• Stipules = small leaf-like outgrowths at the leaf base. Present in some families (rose, pea). When present → stipulate; absent → exstipulate
• In some plants, the leaf base is swollen → called a pulvinus (e.g., legumes like *Mimosa*). Responsible for leaf movements (thigmonasty)
• The midrib and veins form the venation pattern — key for identifying monocots vs dicots

Venation

The arrangement of veins in the lamina is called venation. Dicots typically have reticulate (net-like), monocots have parallel venation.

Venation is the pattern of veins (vascular bundles) in the leaf lamina. It determines how water and nutrients are distributed across the leaf.

• Pinnate reticulate = one prominent midrib with lateral veins branching off it. Example: mango leaf
• Palmate reticulate = multiple main veins radiate from the leaf base like fingers. Example: *Cucurbita* (pumpkin leaf)
• Exception: Some monocots have reticulate venation — e.g., *Smilax*, *Alocasia*. Some dicots have parallel venation — e.g., *Calophyllum* (beauty leaf)

Simple vs Compound Leaves

In simple leaves, the lamina is a single continuous blade. In compound leaves, the lamina is divided into separate leaflets. Compound leaves are further classified as pinnate or palmate.

The key question: is the incision of the lamina deep enough to reach the midrib/petiole? - Simple leaf — lamina is one continuous piece (may have lobes, but incisions don't reach the midrib). Example: mango, peepal, hibiscus - Compound leaf — lamina is divided into distinct leaflets, each attached to a common axis (rachis). Example: neem, rose, pea

• Pinnately compound — leaflets arranged on both sides of a central rachis (like a feather). Example: neem (unipinnate), *Mimosa* (bipinnate)
• Palmately compound — leaflets radiate from a single point at the tip of the petiole (like fingers from a palm). Example: *Bombax* (silk cotton), *Cannabis*
• How to distinguish a compound leaf from a branch: axillary bud is at the base of the leaf (petiole), NOT at the base of each leaflet. Leaflets have no axillary buds

Quick recall

How do you tell a compound leaf from a branch with simple leaves?

Check for an axillary bud. A compound leaf has an axillary bud only at the base of the whole leaf (where petiole meets the stem). Individual leaflets do NOT have axillary buds. A branch would have buds at the base of each leaf.

Phyllotaxy

Phyllotaxy is the pattern of leaf arrangement on a stem. The three types are alternate, opposite, and whorled.

Phyllotaxy = the arrangement of leaves on the stem/branch. Why does it matter? Optimal phyllotaxy ensures maximum light exposure — leaves don't shadow each other.

• Alternate (spiral) — one leaf per node, leaves alternate sides. Example: sunflower, mustard, *Hibiscus*. Most common type
• Opposite — two leaves per node, on opposite sides. Can be superimposed (all pairs in same plane) or decussate (each pair at 90 degrees to the one below). Example: *Calotropis* (aak), guava
• Whorled — three or more leaves per node, forming a circle (whorl). Example: *Nerium* (kaner/oleander), *Alstonia*

Leaf Modifications

Leaves modify to perform functions beyond photosynthesis — climbing (tendrils), defense (spines), nutrient trapping (pitcher, bladder), water storage, and even photosynthesis replacement (phyllode).

When survival demands it, leaves sacrifice their photosynthetic role and transform into specialized structures.

• Leaf tendrils — leaflets or entire leaves coil around supports for climbing. Example: pea (leaflets become tendrils), glory lily (*Gloriosa* — leaf tip becomes tendril)
• Leaf spines — leaves modified into sharp spines for defense + reducing water loss. Example: *Opuntia* (cactus) — the spines are modified leaves; the flat green pads are stems (phylloclades)
• Pitcher (insectivorous) — leaf forms a pitcher-shaped trap to catch insects for nitrogen. Example: *Nepenthes* (pitcher plant). Lamina → lid, petiole → pitcher body
• Bladder trap — in *Utricularia* (bladderwort), leaf segments form tiny bladders that suck in small aquatic organisms
• Storage leaves — fleshy leaves store water/food. Example: onion (scale leaves), *Aloe*, *Bryophyllum*
• Phyllode — petiole becomes flattened, green, and leaf-like, replacing the lamina for photosynthesis. Example: Australian acacia (*Acacia auriculiformis*)
• *Bryophyllum* — leaf margins bear adventitious buds that fall off and grow into new plants (vegetative propagation)

Quick recall

Tendril of pea is a leaf modification, but tendril of cucumber is a stem modification. How to tell?

Pea tendrils arise from the leaf (modified leaflets on the compound leaf). Cucumber tendrils arise from the axillary bud position (stem). Check the origin point — leaf position vs axillary bud position.

Inflorescence — How Flowers Arrange Themselves

Inflorescence is the arrangement of flowers on the floral axis. The two main types are racemose (indefinite — growing tip never becomes a flower) and cymose (definite — growing tip terminates in a flower). Special types include cyathium and verticillaster.

Racemose (Indefinite)

In racemose inflorescence, the main axis continues to grow indefinitely. Flowers develop laterally in acropetal succession (oldest at base, youngest at tip).

In racemose inflorescence, the main axis (peduncle) has unlimited growth — it never terminates in a flower. New flowers keep appearing at the tip, while older flowers are at the base. This bottom-to-top opening pattern is called acropetal succession.

• Raceme — main axis elongated, flowers pedicellate (stalked). Example: mustard (*Brassica*), radish, larkspur. The classic racemose type
• Spike — like a raceme but flowers are sessile (no pedicel). Example: amaranth (*Amaranthus*), wheat ear
• Catkin — pendulous (hanging) spike with unisexual flowers. Example: mulberry, birch, willow
• Spadix — spike with a fleshy axis enclosed in a large, often colorful spathe (bract). Example: banana, maize (female), *Colocasia*, *Arum*
• Corymb — flowers have pedicels of different lengths — lower pedicels are longer, so all flowers come to the same level. Example: candytuft (*Iberis*)
• Umbel — pedicels of equal length arise from the same point like an umbrella. Example: *Centella* (brahmi), carrot, fennel. A cluster of bracts (involucre) at the base is common
• Capitulum (head) — the most advanced racemose type. Flowers (florets) are sessile on a flat receptacle. What looks like one flower (sunflower, marigold) is actually hundreds of tiny florets. Surrounded by an involucre of bracts

Cymose (Definite)

In cymose inflorescence, the main axis terminates in a flower. Further flowers develop from lateral branches below the terminal flower. Opening is centrifugal (center first, periphery later).

In cymose inflorescence, the main axis terminates in a flower, so it has limited growth. Newer flowers develop from lateral buds below the terminal flower. The oldest flower is at the center/top and the youngest is at the periphery — this is basipetal succession (centrifugal opening).

• Monochasial (uniparous) cyme — only ONE lateral branch develops below the terminal flower. Two sub-types:
• — Helicoid cyme: successive branches develop on the same side. Example: *Heliotropium*, *Saraca*
• — Scorpioid cyme: successive branches develop on alternate sides (zigzag). Example: *Ranunculus* (buttercup), cotton
• Dichasial (biparous) cyme — TWO lateral branches develop below the terminal flower, each terminating in a flower. Example: jasmine (*Jasminum*), *Dianthus* (pink), *Bougainvillea*
• Polychasial (multiparous) cyme — MORE THAN TWO lateral branches below the terminal flower. Example: *Calotropis*, *Nerium* (oleander)

Special Types

Some inflorescences don't fit neatly into racemose or cymose. These special types are NEET favorites because they look deceptively like single flowers.

Some inflorescences are so specialized they deserve their own category. They often mimic single flowers, confusing students and pollinators alike.

• Cyathium — looks like a single flower but is an inflorescence. A cup-shaped involucre surrounds a central female flower (single pistil on a long stalk) and multiple male flowers (each reduced to a single stamen). Example: *Euphorbia*, poinsettia. The colorful 'petals' are actually bracts
• Verticillaster — a condensed dichasial cyme that forms a false whorl of flowers around the stem at each node. Example: *Salvia*, tulsi (*Ocimum*), mint — all in Family Lamiaceae
• Hypanthodium — the receptacle forms a hollow, pear-shaped structure (fig) with flowers lining the inner surface. Opening at the top (ostiole). Example: *Ficus* (fig, banyan, peepal). What you eat as a 'fig fruit' is actually an inflorescence!

The Flower — Reproductive Unit in Full Detail

A flower is the reproductive unit of angiosperms with four whorls: calyx (sepals), corolla (petals), androecium (stamens/male), and gynoecium (carpels/female). Key concepts include symmetry, fusion patterns, stamen arrangements, ovary position, and placentation types — all essential for writing floral formulas.

Flower Symmetry & Basic Terms

Flowers vary in symmetry, completeness, sexuality, and ovary position. These terms form the vocabulary for describing any flower.

Before dissecting individual whorls, you need the vocabulary to describe any flower. NCERT and NEET questions rely heavily on these terms.

• Actinomorphic (radial symmetry, %) — can be divided into two equal halves along any vertical plane. Example: mustard, *Datura*, lily
• Zygomorphic (bilateral symmetry, ↑) — can be divided into two equal halves along only one vertical plane. Example: pea, bean, *Cassia*, *Salvia*
• Asymmetric — cannot be divided into two equal halves by any plane. Example: *Canna*
• Bisexual (hermaphrodite, ⚥) — both androecium and gynoecium present. Example: mustard, rose, lily
• Unisexual — only one sex organ. Staminate (male, ♂) = only androecium. Pistillate (female, ♀) = only gynoecium. Example: cucumber, maize, papaya
• Complete flower — all four whorls present. Incomplete — one or more whorls missing
• Hypogynous — ovary superior (sits above other whorls). Example: mustard, *Hibiscus*
• Perigynous — ovary half-inferior (other whorls at same level). Example: rose, peach, plum
• Epigynous — ovary inferior (sits below other whorls). Example: apple, cucumber, sunflower

Calyx & Corolla

Calyx (sepals) protects the bud; corolla (petals) attracts pollinators. Both can be free or fused, and their arrangement (aestivation) is a key identification feature.

The calyx (outermost whorl) and corolla (second whorl) are the accessory whorls — they don't directly produce gametes but play crucial roles in protection and pollination.

• Polysepalous = sepals free. Gamosepalous = sepals fused. Example: *Hibiscus* has gamosepalous calyx
• Polypetalous = petals free. Gamopetalous = petals fused. Example: *Datura* has gamopetalous corolla; mustard has polypetalous
• When calyx is persistent (stays after flowering) → persistent calyx. Example: tomato, brinjal (calyx remains on the fruit)
• When calyx falls as flower opens → caducous. Example: poppy. When it falls after fertilization → deciduous. Example: mustard

Aestivation is the arrangement of sepals/petals in the bud. This is a KEY identification character:

• Valvate — sepals/petals touch at edges without overlapping. Example: *Calotropis*
• Twisted (contorted) — each member overlaps the next one in one direction (like a pinwheel). Example: *Hibiscus*, cotton
• Imbricate — margins overlap irregularly — not in a regular spiral. Example: *Cassia*, *Caesalpinia*
• Vexillary (papilionaceous) — special aestivation of the pea family: one large standard (posterior), two lateral wings, two fused keel petals (anterior). Example: pea, bean — ONLY in Papilionaceae/Fabaceae

Androecium

The androecium is the male reproductive whorl. Stamens vary in number, length, attachment, and fusion patterns — all critical for floral formula writing.

Each stamen consists of a filament (stalk) and an anther (pollen-producing head). The anther is typically bilobed with 4 pollen sacs (microsporangia). The filament connects the anther to the thalamus or other floral parts.

• Stamen attachment: Epipetalous = stamens attached to petals (e.g., brinjal, *Datura* — Solanaceae). Epiphyllous = attached to perianth/tepals (e.g., lily — Liliaceae)
• Filament fusion: Monoadelphous = all filaments fused into one bundle (e.g., *Hibiscus*, cotton). Diadelphous = two bundles, typically (9)+1 (e.g., pea). Polyadelphous = many bundles (e.g., citrus)
• Anther fusion: Syngenesious = anthers fused, filaments free (e.g., sunflower — Asteraceae/Compositae). Synandrous = both anthers and filaments fused (rare, e.g., *Cucurbita*)
• Stamen length: Didynamous = 4 stamens, 2 long + 2 short (e.g., *Salvia* — Lamiaceae). Tetradynamous = 6 stamens, 4 long + 2 short (e.g., mustard — Brassicaceae)
• Sterile stamen = staminode (no functional pollen). Example: *Cassia*

Gynoecium & Placentation

The gynoecium (female whorl) consists of carpels. The arrangement of ovules inside the ovary (placentation) is a key classification character. Five types: marginal, axile, parietal, basal, and free central.

Each carpel (pistil) has three parts: stigma (pollen receptor), style (connecting tube), and ovary (contains ovules). When carpels are free → apocarpous (e.g., lotus, rose). When fused → syncarpous (e.g., mustard, tomato).

Placentation = the arrangement of ovules on the placenta within the ovary. This determines how seeds are distributed inside the fruit.

• Marginal — ovules along the ventral suture (margin) of a single carpel. Ovary unilocular. Example: pea (Fabaceae) — open a pea pod and see seeds lined along one edge
• Axile — ovules on the central axis where septa meet. Ovary multilocular (divided into chambers). Example: tomato, lemon, *Hibiscus*, lily
• Parietal — ovules on the inner wall of the ovary. Ovary unilocular (septa break down or absent). Example: mustard (Brassicaceae), cucumber (Cucurbitaceae)
• Basal — single ovule at the base of the ovary. Ovary unilocular. Example: sunflower (Asteraceae), marigold
• Free central — ovules on a central column (axis) that is NOT connected to the ovary wall by septa. Ovary unilocular. Example: *Dianthus*, *Primula*
• Superficial — ovules on the inner surface of septa in a multilocular ovary (all surfaces). Example: *Nymphaea* (water lily)

Fruit & Seed — From Ovary to Offspring

After fertilization, the ovary develops into a fruit and ovules into seeds. Fruits are classified as simple (dry or fleshy), aggregate, or composite. Seeds are either monocot (one cotyledon, endospermic) or dicot (two cotyledons). A coconut is a drupe, a strawberry's 'seeds' are on the outside, and an apple's fleshy part is the thalamus, not the ovary.

True vs False Fruits

In true fruits, only the ovary wall develops into the fruit. In false fruits, other floral parts (thalamus, calyx) also contribute.

After fertilization, the ovary matures into a fruit and the ovules mature into seeds. The ovary wall becomes the pericarp (fruit wall). But sometimes other parts of the flower also become part of the 'fruit' — and that changes the classification.

• True fruit — develops only from the ovary. Example: mango, tomato, pea pod, coconut
• False fruit (pseudocarp) — other floral parts (thalamus, calyx, receptacle) also form part of the fruit. Example: apple (fleshy part = thalamus), strawberry (fleshy part = receptacle), cashew (fleshy 'apple' = pedicel/thalamus)
• Parthenocarpic fruit — develops WITHOUT fertilization (seedless). Example: banana, grapes (seedless varieties). Can be induced by hormones (auxin, gibberellin)

Simple Fruits

Simple fruits develop from a single ovary of a single flower. Dry fruits (dehiscent/indehiscent) and fleshy fruits (drupe, berry, pome) are the two main categories.

Simple fruits develop from a single ovary of a single flower. They can be either dry (pericarp dries out at maturity) or fleshy (pericarp remains soft and juicy).

Dry fruits are further divided based on whether they open to release seeds:

• Dry dehiscent (open at maturity): Legume/pod = splits along both sutures (pea, bean). Capsule = multi-chambered, opens by pores/slits (cotton, *Datura*, poppy). Siliqua = two-chambered, seeds on false septum (mustard — Brassicaceae)
• Dry indehiscent (do not open): Achene = small, single-seeded, pericarp free from seed coat (sunflower). Caryopsis = single-seeded, pericarp fused with seed coat (wheat, rice, maize — all grains!). Nut = hard, woody pericarp (cashew nut, walnut). Cypsela = achene with persistent calyx/pappus (dandelion — the fluffy parachute)

Fleshy fruits have a soft, juicy pericarp with three layers: epicarp (outer skin), mesocarp (middle fleshy layer), endocarp (inner layer).

• Drupe — one-seeded, endocarp is hard and stony (forms the 'stone/pit'). Example: mango (mesocarp = edible pulp), coconut (mesocarp = fibrous husk, endocarp = hard shell), peach, plum, cherry. Coconut is a drupe, NOT a nut!
• Berry — many-seeded, endocarp is absent or thin (no stone). Entire pericarp is fleshy. Example: tomato, grape, banana, *Cucurbita* (gourd family). Surprisingly, banana is a berry but strawberry is NOT
• Pome — fleshy part is the thalamus (not ovary wall). Ovary forms the papery core. Example: apple, pear. This makes it a false fruit too
• Hesperidium — special berry with leathery rind. Example: orange, lemon (Citrus family). Juice-filled hair-like structures = edible part
• Pepo — berry with hard rind (from receptacle). Example: cucumber, watermelon (Cucurbitaceae)

Quick recall

Wheat grain — which type of fruit? Is the seed coat separate from the pericarp?

Wheat grain is a caryopsis (dry, indehiscent). The pericarp is fused with the seed coat — you cannot separate them. That's why wheat bran (outer layer) contains both pericarp and seed coat together.

Aggregate & Composite Fruits

Aggregate fruits develop from multiple free carpels of a single flower. Composite fruits develop from an entire inflorescence.

Not all fruits come from a single ovary. Some develop from multiple carpels of one flower, and others from an entire cluster of flowers.

• Aggregate fruit (etaerio) — develops from a single flower with multiple free carpels (apocarpous gynoecium). Each carpel forms a fruitlet. Example: raspberry (etaerio of drupes), strawberry (etaerio of achenes on fleshy receptacle), lotus, *Annona* (custard apple)
• Composite fruit (multiple fruit) — develops from an entire inflorescence (many flowers fusing together). Example: pineapple (from a spike — all ovaries, bracts, and axis fuse), fig (*Ficus* — from a hypanthodium inflorescence), jackfruit, mulberry

Seed Structure

Seeds develop from ovules after fertilization. Dicot seeds (e.g., gram) have two cotyledons and may be non-endospermic. Monocot seeds (e.g., maize) have one cotyledon (scutellum) and are endospermic.

A seed has three main parts: seed coat (protective covering from integuments), cotyledon(s) (embryonic leaves — food storage or absorption), and embryo (future plant — radicle + plumule + hypocotyl).

• Hilum — oval scar on the seed coat where the seed was attached to the fruit (funiculus)
• Micropyle — tiny pore near the hilum through which water enters during germination
• Endospermic seed — food stored in endosperm (castor, coconut, maize). Non-endospermic seed — endosperm consumed during development, food stored in cotyledons (gram, pea, bean)
• In monocots: scutellum = the single cotyledon (shield-shaped, pressed against endosperm). Coleoptile = sheath covering plumule. Coleorhiza = sheath covering radicle
• Aleurone layer — protein-rich outermost layer of endosperm in cereals (wheat, rice). Important in germination — produces enzymes

Floral Formula & Diagram — The Shorthand for Flower Description

A floral formula uses symbols to encode every feature of a flower in one line: symmetry, sex, number and fusion of sepals/petals/stamens/carpels, and ovary position. A floral diagram is the cross-sectional map. Mastering these is essential for family-based NEET questions.

Floral Formula Symbols

Each symbol in a floral formula represents a specific flower feature. Learn them once and you can decode any flower's blueprint.

A floral formula is a compact notation that captures the complete structure of a flower. It reads like a code — once you know the symbols, you can reconstruct the entire flower from one line.

• Br = bracteate (bract present). Ebr = ebracteate (no bract)
• ⊕ or % = actinomorphic (radial symmetry). ↑ or ⊘ = zygomorphic (bilateral symmetry)
• ⚥ = bisexual. ♂ = staminate (male). ♀ = pistillate (female)
• K = calyx (sepals). C = corolla (petals). P = perianth (when sepals and petals are similar/tepals)
• A = androecium (stamens). G = gynoecium (carpels)
• Subscript number after letter = count of parts. Example: K₅ = 5 sepals, A₁₀ = 10 stamens
• Parentheses () = parts are fused. Example: K(5) = 5 fused sepals (gamosepalous). C(5) = 5 fused petals (gamopetalous)
• G with underline (G̲) = superior ovary (hypogynous). G with overline (Ḡ) = inferior ovary (epigynous)
• ∞ = numerous/many (too many to count). Example: A∞ = many stamens
• A(9)+1 = 9 stamens fused + 1 free (diadelphous, as in pea)

Floral Diagram

A floral diagram is a schematic cross-section of a flower showing the number, arrangement, fusion, and relative positions of all floral parts.

A floral diagram is a ground plan (cross-section) of a flower, drawn as if you sliced through a flower bud horizontally and looked at it from above. It complements the floral formula by showing spatial arrangement.

• Mother axis (main stem) is shown as a dot at the top of the diagram
• Bract (if present) is drawn as a crescent at the bottom (opposite to the mother axis)
• Sepals — outermost whorl, drawn as crescents with their midrib line
• Petals — next whorl inward, drawn similarly but often colored/shaded differently
• Stamens — drawn as cross-sections of anthers (kidney/butterfly shaped). Lines connecting them indicate fusion
• Gynoecium — innermost, shown with carpels, locules, and ovules visible. Number of locules and placentation can be read from the diagram
• Fused parts are shown connected/bracketed. Free parts are drawn separately
• Alternation: Parts of successive whorls typically alternate with each other (petals alternate with sepals, stamens alternate with petals)

Family Descriptions — Fabaceae, Solanaceae & Liliaceae

NCERT describes three families in detail: Fabaceae (pea/legume family — butterfly-shaped flowers, diadelphous stamens, legume fruit), Solanaceae (potato family — fused petals, epipetalous stamens, berry/capsule), and Liliaceae (lily family — trimerous flowers, tepals, axile placentation). Their floral formulas, diagnostic features, and economic importance are NEET gold.

Fabaceae (Papilionaceae)

The third-largest family of flowering plants. Known for butterfly-shaped (papilionaceous) flowers, diadelphous stamens (9)+1, marginal placentation, legume/pod fruit, and root nodules with nitrogen-fixing Rhizobium.

Family Fabaceae (also called Papilionaceae or Leguminosae) is economically the most important family for human nutrition — pulses (dal), beans, groundnut, soybean all come from here. Members are called legumes.

• Habit: Herbs, shrubs, trees, climbers (wide range)
• Root: Taproot with root nodules containing nitrogen-fixing *Rhizobium* bacteria — the defining ecological feature
• Leaf: Alternate, compound (pinnately compound or sometimes trifoliate), stipulate. Stipules may be modified into thorns
• Inflorescence: Racemose — typically a raceme
• Flower: Zygomorphic, bisexual, pentamerous
• Calyx: K(5) — 5 sepals, gamosepalous (fused)
• Corolla: 5 petals, polypetalous but papilionaceous — 1 standard (vexillum, largest, posterior) + 2 wings (alae, lateral) + 2 keel petals (carina, fused, enclose stamens & pistil). Vexillary aestivation
• Androecium: A(9)+1 — diadelphous (9 fused + 1 free). 10 stamens total
• Gynoecium: G̲₁ — monocarpellary, superior ovary, unilocular, marginal placentation
• Fruit: Legume (pod) — dehisces along both sutures
• Seed: Non-endospermic, two cotyledons

Floral formula: ↑ ⚥ K(5) C₁₊₂₊(2) A(9)+1 G̲₁

• Economic importance: Pulses — gram (*Cicer*), moong (*Vigna*), arhar (*Cajanus*), lentil (*Lens*). Oilseeds — groundnut (*Arachis*), soybean (*Glycine*). Fodder — *Trifolium* (clover), *Sesbania*. Timber — *Dalbergia* (rosewood). Dye — indigo (*Indigofera*). Medicinal — *Glycyrrhiza* (mulethi). Ornamental — *Butea*, *Clitoria*, sweet pea (*Lathyrus*)

Solanaceae

A medium-sized family with many food crops and poisonous plants. Characterized by fused tubular/bell-shaped petals, epipetalous stamens, bicarpellary syncarpous ovary with axile placentation, and berry or capsule fruits.

Family Solanaceae includes essential food plants (potato, tomato, brinjal) alongside deadly poisonous ones (belladonna, *Datura*). This duality earned it the name 'nightshade family.'

• Habit: Mostly herbs, some shrubs (very rarely small trees)
• Stem: Herbaceous, sometimes woody at base. Aerial, erect, cylindrical, branched. Often hairy/glandular
• Leaf: Alternate, simple, exstipulate (no stipules). Often with a characteristic pungent smell when crushed
• Inflorescence: Cymose — typically a scorpioid cyme (helicoid in some). Often called 'extra-axillary' because the cyme appears to arise between nodes
• Flower: Actinomorphic, bisexual, pentamerous, hypogynous
• Calyx: K(5) — 5 fused sepals. Persistent (stays on the fruit — visible on top of tomato/brinjal)
• Corolla: C(5) — 5 fused petals (gamopetalous). Tubular or bell-shaped. Valvate aestivation
• Androecium: A₅ — 5 stamens, epipetalous (attached to petals), alternating with petal lobes
• Gynoecium: G̲(2) — bicarpellary, syncarpous, superior ovary, bilocular (but sometimes appears multilocular due to false septum), axile placentation. Placenta swollen with numerous ovules
• Fruit: Berry (tomato, brinjal, *Capsicum*) or capsule (*Datura*, *Petunia*)
• Seed: Many, endospermic

Floral formula: ⊕ ⚥ K(5) C(5) A₅ G̲(2)

• Economic importance: Food — potato (*Solanum tuberosum*), tomato (*Solanum lycopersicum*), brinjal (*Solanum melongena*), chilli (*Capsicum*). Medicinal — belladonna (*Atropa*) — source of atropine, *Datura* — dhatura (poisonous). Tobacco — *Nicotiana tabacum*. Ornamental — *Petunia*, *Cestrum* (night jasmine). Spice — *Capsicum*

Quick recall

What is the key difference between Solanaceae fruit types — when is it a berry vs capsule?

Berry when the entire pericarp is fleshy at maturity (tomato, brinjal, *Capsicum*). Capsule when the pericarp dries and dehisces (*Datura*, *Petunia*). Both come from the same bicarpellary ovary.

Liliaceae

A monocot family with trimerous flowers, perianth of 6 tepals (not differentiated into sepals/petals), 6 epiphyllous stamens, tricarpellary syncarpous ovary with axile placentation. Includes onion, garlic, lily, tulip, and Aloe.

Liliaceae is a monocot family — so expect trimerous flowers (parts in multiples of 3), parallel venation, and a single cotyledon. The perianth is undifferentiated — sepals and petals look alike (tepals).

• Habit: Perennial herbs with underground stems (bulbs, rhizomes, corms)
• Root: Adventitious (fibrous root system — monocot feature)
• Leaf: Mostly basal, simple, alternate. Parallel venation (monocot). Exstipulate. In *Aloe*, leaves are fleshy (succulent). *Smilax* has reticulate venation (exception)
• Inflorescence: Variable — raceme, umbel, or solitary terminal
• Flower: Actinomorphic, bisexual, trimerous, hypogynous
• Perianth: P₃₊₃ or P(3+3) — 6 tepals in two whorls of 3 each. Often petaloid (colorful). Free or fused
• Androecium: A₃₊₃ — 6 stamens in two whorls of 3. Epiphyllous (attached to perianth/tepals)
• Gynoecium: G̲(3) — tricarpellary, syncarpous, superior ovary, trilocular, axile placentation. Many ovules per locule
• Fruit: Capsule (lily, tulip) or berry (*Asparagus*, *Smilax*)
• Seed: Endospermic

Floral formula: ⊕ ⚥ P₃₊₃ A₃₊₃ G̲(3)

• Economic importance: Food — onion (*Allium cepa*), garlic (*Allium sativum*), asparagus (*Asparagus*). Medicinal — *Aloe vera* (skin care, digestion), *Colchicum* (source of colchicine — used to induce polyploidy). Ornamental — tulip (*Tulipa*), lily (*Lilium*), *Gloriosa* (glory lily). Fiber — *Phormium* (New Zealand flax)