This MCQ module is based on: Floral Formula Families
TOPIC 19 OF 45
Floral Formula Families
🎓 Class 11
Biology
CBSE
Theory
Ch 5 – Morphology of Flowering Plants
⏱ ~14 min
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Floral Formula Families
5.10 Semi-Technical Description of a Typical Flowering Plant
Various morphological features are used to describe a flowering plant. The description has to be brief, in a simple and scientific language and presented in a proper sequence. The plant is described beginning with its habit, vegetative characters — roots, stem and leaves and then floral characters — inflorescence and flower parts. After describing various parts of the plant, a floral formula is presented.
Symbols Used in Floral Formula
| Symbol | Meaning |
|---|---|
| Br | Bracteate |
| Ebr | Ebracteate |
| K | Calyx (number of sepals) |
| C | Corolla (number of petals) |
| P | Perianth (when calyx & corolla are not distinguishable) |
| A | Androecium (number of stamens) |
| G | Gynoecium / Carpels — superior ovary |
| Ḡ (G with line below) | Inferior ovary (epigynous) |
| G̲ (G with line above) | Superior ovary written for clarity |
| ⊕ (Plus in circle) | Actinomorphic |
| % | Zygomorphic |
| ⚥ | Bisexual flower |
| ♂ | Male flower |
| ♀ | Female flower |
| ( ) | Fusion of members of the same whorl |
| Underscore between K, C | Adhesion of members of different whorls (e.g., epipetalous) |
| ∞ | Indefinite/numerous |
5.11 Description of Some Important Families
5.11.1 Fabaceae (Papilionoideae of Leguminosae)
Earlier called Papilionoideae — a sub-family of family Leguminosae. It is distributed all over the world.
| Feature | Description |
|---|---|
| Vegetative | Trees, shrubs, herbs; root with nodules (nitrogen fixation) |
| Stem | Erect or climbing |
| Leaves | Alternate, pinnately compound or simple; leaf base pulvinate; stipulate; venation reticulate |
| Inflorescence | Racemose |
| Flower | Bisexual, zygomorphic |
| Calyx | 5 sepals, gamosepalous; imbricate aestivation |
| Corolla | 5 petals, polypetalous, papilionaceous (1 standard/vexillum + 2 wings + 2 keel); vexillary aestivation |
| Androecium | 10 stamens, diadelphous (9+1); anther dithecous |
| Gynoecium | Ovary superior, monocarpellary, unilocular with many ovules; style single, long; stigma simple |
| Fruit | Legume (pod) |
| Seed | One to many, non-endospermic |
| Examples | Pulses (gram, arhar, sem, moong, soybean); edible oil (soybean, groundnut); medicinal (muliathi); ornamental (lupin, sweet pea) |
% ⚥ K(5) C1+2+(2) A(9)+1 G1
5.11.2 Solanaceae
Commonly called the 'potato family'. Widely distributed in tropics, subtropics and temperate regions.
| Feature | Description |
|---|---|
| Vegetative | Mostly herbs, shrubs, small trees; rarely climbers |
| Stem | Herbaceous, rarely woody; aerial; erect; cylindrical; branched; solid or hollow; hairy or glabrous; underground stems in potato |
| Leaves | Alternate, simple, rarely pinnately compound; exstipulate; venation reticulate |
| Inflorescence | Solitary, axillary or cymose |
| Flower | Bisexual, actinomorphic |
| Calyx | 5 sepals, united (gamosepalous), persistent; valvate aestivation |
| Corolla | 5 petals, united (gamopetalous); valvate aestivation |
| Androecium | 5 stamens, epipetalous |
| Gynoecium | Bicarpellary, syncarpous; ovary superior, bilocular, many ovules on swollen axile placentation |
| Fruit | Berry or capsule |
| Seed | Many; endospermic |
| Examples | Food (tomato, brinjal, potato); spice (chilli); medicinal (belladonna, ashwagandha); fumigatory (tobacco); ornamental (petunia) |
⊕ ⚥ K(5) C(5) A5 G(2)
5.11.3 Liliaceae
Commonly called the 'lily family' — a representative monocot family. Plants mostly perennial herbs with underground bulbs/corms/rhizomes.
| Feature | Description |
|---|---|
| Vegetative | Perennial herbs with underground bulbs / corms / rhizomes |
| Leaves | Mostly basal, alternate, linear; exstipulate; parallel venation |
| Inflorescence | Solitary or cymose, often umbellate clusters |
| Flower | Bisexual, actinomorphic |
| Perianth | 6 (3+3) tepals, often united; valvate aestivation |
| Androecium | 6 stamens (3+3); epiphyllous |
| Gynoecium | Tricarpellary, syncarpous; ovary superior, trilocular, axile placentation |
| Fruit | Capsule, rarely berry |
| Seed | Endospermic |
| Examples | Ornamental (tulip, Gloriosa); medicinal (Aloe); vegetables (Asparagus); colchicine (Colchicum) |
⊕ ⚥ P(3+3) A3+3 G(3)
Family Comparison
| Feature | Fabaceae | Solanaceae | Liliaceae |
|---|---|---|---|
| Class | Dicot | Dicot | Monocot |
| Symmetry | Zygomorphic | Actinomorphic | Actinomorphic |
| Calyx + Corolla | K(5) C1+2+(2) | K(5) C(5) | P(3+3) |
| Androecium | (9)+1 diadelphous | 5 epipetalous | 3+3 epiphyllous |
| Gynoecium | Monocarpellary, unilocular | Bicarpellary, bilocular | Tricarpellary, trilocular |
| Placentation | Marginal | Axile (swollen) | Axile |
| Fruit | Legume (pod) | Berry / capsule | Capsule |
| Aestivation | Vexillary | Valvate | Valvate |
Interactive: Family Identifier
Pick distinctive features and see which family the flower belongs to:
Family: —
Pick all three features.
Activity 5.4 — Build Your Own Floral Formula
Setup: Get a fresh datura/petunia/tomato flower. Open it carefully on a white sheet.
Predict: Count sepals, petals, stamens, carpels. Note symmetry and ovary position. Build the floral formula.
Datura observations:
- Bracteate (small bract below pedicel)
- Bisexual flower → ⚥
- Actinomorphic → ⊕
- 5 sepals fused → K(5)
- 5 petals fused (funnel-shaped) → C(5)
- 5 stamens, attached to petals → A5 (epipetalous)
- 2 carpels fused, ovary superior, bilocular → G(2)
Final formula: Br ⊕ ⚥ K(5) C(5) A5 G(2)
Confirms: Datura belongs to Solanaceae.
Worked Examples
Worked Example 1: Decode a Floral Formula
Decode: % ⚥ K(5) C1+2+(2) A(9)+1 G1. To which family does it belong?
Decoding:
- % = zygomorphic symmetry
- ⚥ = bisexual flower
- K(5) = 5 sepals fused (gamosepalous)
- C1+2+(2) = 5 petals: 1 standard + 2 wings (free) + 2 keel (fused) — papilionaceous, vexillary aestivation
- A(9)+1 = 10 stamens, diadelphous (9 fused + 1 free)
- G1 = monocarpellary, ovary superior
Worked Example 2: Spot the Monocot Feature
Why is Liliaceae floral formula written using P (perianth) and not K + C?
In Liliaceae (lily, tulip), the sepals and petals look identical — same colour, same shape, same texture. They cannot be visually distinguished into a green calyx (K) and a coloured corolla (C).
When this happens, the entire floral covering is called the perianth (P), and individual members are called tepals.
P(3+3) = 6 tepals arranged in 2 whorls of 3 — typical trimerous monocot pattern.
When this happens, the entire floral covering is called the perianth (P), and individual members are called tepals.
P(3+3) = 6 tepals arranged in 2 whorls of 3 — typical trimerous monocot pattern.
Competency-Based Questions
Q1. The diadelphous condition (9+1) of stamens is characteristic of: L1 Remember
Answer: (c) Fabaceae. 9 stamens fuse into a tube + 1 free (vexillary stamen) — unique signature of pea family.
Q2. The placentation in Solanaceae is: L2 Understand
Answer: (b). Solanaceae has a bicarpellary syncarpous bilocular ovary with axile placentation; the placenta is swollen and bears many ovules.
Q3. Write the floral formula for a hibiscus flower (5 sepals fused, 5 petals free, many stamens fused, 5 carpels fused, ovary superior, actinomorphic, bisexual). L3 Apply
Floral formula: Br ⊕ ⚥ K(5) C5 A(∞) G(5)
Explanation: Bracteate, actinomorphic, bisexual; 5 fused sepals; 5 free petals; many stamens fused into a tube (monoadelphous); 5 fused carpels with superior ovary. Family: Malvaceae.
Explanation: Bracteate, actinomorphic, bisexual; 5 fused sepals; 5 free petals; many stamens fused into a tube (monoadelphous); 5 fused carpels with superior ovary. Family: Malvaceae.
Q4. Analyse: Tomato and brinjal both belong to Solanaceae but tomato fruit is a berry while brinjal is also a berry. Compare and contrast their floral and fruit features. L4 Analyse
Common (family) features: Both have 5 fused sepals (persistent), 5 fused petals, 5 epipetalous stamens, bicarpellary syncarpous superior ovary with axile placentation, fruit = berry.
Differences:
Differences:
- Tomato: Yellow flowers; soft, fleshy red berry; thin pericarp; many small seeds in pulpy mesocarp.
- Brinjal: Purple flowers; large fleshy berry; thick pericarp with many small seeds; persistent calyx remains attached to fruit.
Q5. Create: Design a dichotomous key to distinguish Fabaceae, Solanaceae, and Liliaceae using only floral characters. L6 Create
Dichotomous Key:
- Flower zygomorphic, papilionaceous, 10 stamens (9+1) ............... Fabaceae
- Flower actinomorphic ............... go to 2
- 2. Calyx and corolla distinguishable; 5 epipetalous stamens; bicarpellary ............... Solanaceae
- 2. Perianth (tepals 3+3); 6 stamens (3+3); tricarpellary; parallel-veined leaves ............... Liliaceae
Assertion–Reason Questions
Choose: (A) Both true, R explains A. (B) Both true, R doesn't explain A. (C) A true, R false. (D) A false, R true.
A: The floral formula of Liliaceae uses P instead of K and C.
R: In Liliaceae, sepals and petals are not distinguishable; both look identical.
Answer: (A). Both true; R explains A. When sepals and petals are not distinguishable, the entire whorl is called perianth (P) made of tepals.
A: Fabaceae plants are agriculturally very important.
R: They have root nodules with Rhizobium that fix atmospheric nitrogen.
Answer: (A). Both true; R explains A. Nitrogen fixation enriches soil naturally; Fabaceae crops (pulses) are pivotal in crop rotation and provide protein-rich seeds.
A: Solanaceae has bicarpellary, syncarpous gynoecium.
R: The carpels are placed obliquely.
Answer: (B). Both are true but R does not directly explain A. Bicarpellary + syncarpous = 2 fused carpels; oblique placement is an additional feature distinct from the 'fused' nature.
Frequently Asked Questions - Floral Formula Families
What is the main concept covered in Floral Formula Families?
In NCERT Class 11 Biology Chapter 5 (Morphology of Flowering Plants), "Floral Formula Families" covers the core biological structures, functions, and classifications students need for board exam success. The MyAiSchool lesson explains the topic with definitions, labelled diagrams, comparison tables, and interactive simulations. Scientific terminology and ecological/physiological significance are highlighted throughout to build conceptual depth aligned with CBSE 2025-26 syllabus.
How is Floral Formula Families useful in real-life or applied biology?
Real-life applications of "Floral Formula Families" from NCERT Class 11 Biology Chapter 5 include medical diagnostics, agriculture, food preservation, biotechnology, ecological monitoring, and public health. The MyAiSchool lesson links every biological concept to a tangible application so students see biology as a problem-solving framework for living systems, not just textbook content.
What are the key terms students should memorize for Floral Formula Families?
Key terms in "Floral Formula Families" (NCERT Class 11 Biology Chapter 5 Morphology of Flowering Plants) are tabulated in the MyAiSchool key-terms grid. Students should memorize each term with its precise definition, function, and example. Terminology is high-yield in CBSE board exams — 1-mark MCQs and 2-mark short answers test definitions directly. The Summary section provides a printable quick-reference card.
How does this part connect to other parts of Chapter 5?
NCERT Class 11 Biology Chapter 5 (Morphology of Flowering Plants) is structured so each part builds biological understanding sequentially. "Floral Formula Families" connects to neighbouring parts via shared classifications, structural hierarchies, and physiological processes. The MyAiSchool lesson cross-references related concepts with internal links so students can navigate the whole chapter as one connected biological story rather than disconnected fragments.
What types of CBSE board questions come from Floral Formula Families?
CBSE board questions from "Floral Formula Families" typically include: (1) 1-mark MCQs on definitions and classification, (2) 2-mark short-answer differences/comparisons, (3) 3-mark labelled-diagram questions, (4) 5-mark long-answer essays combining structure + function + significance. The MyAiSchool lesson tags each Competency-Based Question (CBQ) with Bloom level (L1-L6) so students know how to study for each weight.
How can students use the interactive simulation effectively?
The interactive simulation in the "Floral Formula Families" lesson allows students to explore biological structures, classifications, or processes using selectors and sliders, with live visual feedback. To use it effectively: (1) explore each option/state, (2) compare with textbook diagrams, (3) note the function changes, (4) try the integrated practice quiz. The simulation reinforces visual-spatial understanding that pure text-based study cannot.
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