The trap that costs marks: NEET repeatedly asks you to match a plant family with its floral formula, placentation type, or fruit type — and the distractors swap features between Fabaceae, Solanaceae, and Liliaceae. The high-frequency confusion is placentation: Fabaceae is marginal, Solanaceae is axile, and Liliaceae is axile — students merge the last two or assign parietal (which belongs to Brassicaceae).
Three families, locked features:
Fabaceae (Papilionaceae) — Floral formula: % ⚥ K(5) C1+2+(2) A(9)+1 G1. Aestivation: vexillary (descending imbricate). Androecium: diadelphous (9 fused + 1 free). Gynoecium: monocarpellary, superior ovary, marginal placentation. Fruit: legume. Examples: pea, gram, soybean.
Solanaceae — Floral formula: ⊕ ⚥ K(5) C(5) A5 G(2). Aestivation: valvate (calyx), twisted (corolla in Datura). Androecium: epipetalous (5 stamens attached to petals). Gynoecium: bicarpellary, syncarpous, superior, axile placentation. Fruit: berry or capsule. Examples: tomato, potato, petunia, Datura.
Liliaceae — Floral formula: ⊕ ⚥ P(3+3) A3+3 G(3). Perianth: tepals (not differentiated into calyx/corolla), 6 in two whorls. Androecium: 6 stamens in two whorls. Gynoecium: tricarpellary, syncarpous, superior, axile placentation. Fruit: capsule or berry. Examples: Allium (onion), Colchicum, lily.
Watch-out: When you see "axile placentation + superior ovary," do NOT auto-select Solanaceae — Liliaceae shares both features. The differentiator is perianth structure: tepals (undifferentiated) = Liliaceae; distinct calyx + corolla = Solanaceae.
(References: Solanaceae — NCERT Class 11 Biology Chapter 5, page 69; Fabaceae and Liliaceae — NCERT Biology Lab Manual Class 11, Exercise 11, pages 61–65. The current NCERT textbook describes only Solanaceae; NCERT's Class 11 Biology Laboratory Manual describes all three.)
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
The floral formula % ⚥ K(5) C1+2+(2) A(9)+1 G1 represents which family?
Answer: C. This is the standard floral formula of Fabaceae (Papilionaceae) — zygomorphic symmetry (%), diadelphous androecium (9)+1, monocarpellary gynoecium. NCERT Biology Lab Manual Class 11, Exercise 11, page 62.
Why A is wrong: A is wrong because Solanaceae has actinomorphic symmetry (⊕), pentamerous fused corolla C(5), and epipetalous stamens A5 — none matching the zygomorphic formula shown. (trap: placentation/symmetry confusion between families)
Why B is wrong: B is wrong because Liliaceae has trimerous perianth P(3+3) with 6 stamens A3+3 and tricarpellary gynoecium G(3) — completely different formula structure. (trap: confusing axile-placentation families)
Why D is wrong: D is wrong because Brassicaceae has tetramerous formula with cruciform corolla C4, tetradynamous stamens A2+4, and parietal placentation — no feature matches. (trap: mixing up cross-shaped corolla families)
Which type of aestivation is characteristic of the corolla in Fabaceae?
Answer: A. Fabaceae (papilionaceous corolla) shows vexillary (descending imbricate) aestivation — the large standard petal overlaps the wing petals, which overlap the keel petals. NCERT Class 11 Biology Chapter 5, page 64.
Why B is wrong: B is wrong because twisted aestivation (each petal overlapping the next in one direction) is characteristic of china rose (Malvaceae) and Datura corolla — not papilionaceous flowers. (trap: aestivation type confusion)
Why C is wrong: C is wrong because imbricate is a general overlap pattern; Fabaceae specifically shows vexillary (a specialised form of descending imbricate) which is its diagnostic feature — plain 'imbricate' is incorrect terminology for the papilionaceous arrangement. (trap: aestivation type confusion)
Why D is wrong: D is wrong because valvate aestivation (margins just touching, no overlap) is seen in Calotropis calyx and Solanaceae calyx — not Fabaceae corolla. (trap: aestivation type confusion)
Placentation in Solanaceae is:
Answer: C. Solanaceae has a bicarpellary syncarpous ovary with axile placentation — ovules attached to the central axis where carpel margins meet. NCERT Class 11 Biology Chapter 5, page 69.
Why A is wrong: A is wrong because marginal placentation (ovules along the ventral suture of a single carpel) is the diagnostic feature of Fabaceae, not Solanaceae. (trap: placentation confusion — axile vs marginal between families)
Why B is wrong: B is wrong because parietal placentation (ovules on the inner ovary wall) belongs to Brassicaceae (mustard family), not Solanaceae. (trap: placentation confusion — parietal vs axile)
Why D is wrong: D is wrong because free central placentation (ovules on a free-standing central column, no septa) is seen in Dianthus (Caryophyllaceae) and Primulaceae — Solanaceae retains septa with axile arrangement. (trap: placentation confusion — free central vs axile)
Which of the following is a distinguishing feature of Liliaceae that separates it from Solanaceae?
Answer: D. Both families share superior ovary, axile placentation, and syncarpous gynoecium. The key distinguishing feature is that Liliaceae has undifferentiated perianth (6 tepals in two whorls of 3) rather than distinct calyx and corolla. NCERT Biology Lab Manual Class 11, Exercise 11, pages 64–65.
Why A is wrong: A is wrong because both Solanaceae and Liliaceae have a superior ovary — this feature cannot distinguish between them. (trap: assuming ovary position varies between these families)
Why B is wrong: B is wrong because both families show axile placentation — this shared feature is precisely what causes confusion between them. (trap: placentation confusion between axile-placentation families)
Why C is wrong: C is wrong because both have syncarpous gynoecium (fused carpels) — Solanaceae is bicarpellary syncarpous and Liliaceae is tricarpellary syncarpous, but syncarpous alone doesn't separate them. (trap: focusing on fusion rather than carpel number)
The androecium in Solanaceae is described as epipetalous because:
Answer: B. Epipetalous means stamens are adnate (attached) to the petals/corolla tube. In Solanaceae, the 5 stamens arise from the fused corolla (gamopetalous), hence epipetalous. NCERT Class 11 Biology Chapter 5, page 69.
Why A is wrong: A is wrong because stamens fused to each other forming a tube describes syngenesous condition (as in Asteraceae), not the epipetalous condition of Solanaceae where stamens attach to petals, not to each other. (trap: confusing 'attached to petals' with 'fused among themselves')
Why C is wrong: C is wrong because alternation with sepals describes positional arrangement (alternipetalous), not the mode of attachment — epipetalous specifically means physical fusion to the corolla, regardless of positional alternation. (trap: confusing spatial position with structural attachment)
Why D is wrong: D is wrong because stamens of two different lengths describes the didynamous (2+2) or tetradynamous (4+2) condition seen in Lamiaceae or Brassicaceae — Solanaceae has 5 equal stamens attached to petals. (trap: mixing up stamen conditions across families)
A student identifies a plant with the following features: monocarpellary ovary, marginal placentation, diadelphous stamens, and legume fruit. The plant belongs to:
Answer: D. Monocarpellary ovary + marginal placentation + diadelphous (9)+1 stamens + legume fruit is the diagnostic combination for Fabaceae (Papilionaceae). NCERT Biology Lab Manual Class 11, Exercise 11, page 62.
Why A is wrong: A is wrong because Liliaceae has tricarpellary syncarpous gynoecium with axile placentation and 6 free stamens — none of the listed features (monocarpellary, marginal, diadelphous, legume) match. (trap: random family assignment without checking features)
Why B is wrong: B is wrong because Solanaceae has bicarpellary syncarpous ovary with axile placentation and epipetalous stamens giving berry/capsule fruits — diadelphous stamens and legume fruit are absent. (trap: confusing family-diagnostic features)
Why C is wrong: C is wrong because Brassicaceae has bicarpellary syncarpous ovary with parietal placentation, tetradynamous stamens (4+2), and siliqua/silicula fruit — no feature matches Fabaceae's monocarpellary-marginal-diadelphous combination. (trap: confusing placentation types between families)
Which of the following correctly matches the plant with its family and fruit type?
Answer: A. Potato (Solanum tuberosum) belongs to Solanaceae and produces berry fruits (the green fruits above ground, not the tuber). NCERT Class 11 Biology Chapter 5, pages 68–69.
Why B is wrong: B is wrong because pea belongs to Fabaceae (not Solanaceae) and produces a legume fruit — both family and actual fruit type are swapped in this option. (trap: swapping family assignments between common plants)
Why C is wrong: C is wrong because tomato does belong to Solanaceae (not Fabaceae) and does produce a berry — the family assignment is incorrect here. (trap: knowing tomato is a berry but misassigning the family)
Why D is wrong: D is wrong because onion (Allium) belongs to Liliaceae (not Fabaceae) and produces a capsule — the family assignment is incorrect. (trap: random family-plant pairing without recalling actual classification)
A flower shows a gamopetalous corolla, epipetalous stamens, and a bicarpellary, syncarpous, superior ovary with axile placentation. A classmate says: "It must be Liliaceae, because the placentation is axile." What is the flaw in this reasoning, and which feature actually settles the identification?
Answer: A. Solanaceae's gynoecium is described as "bicarpellary obligately placed, syncarpous; ovary superior, bilocular, placenta swollen with many ovules, axile" (NCERT Class 11 Biology Chapter 5, page 69), with a distinct calyx and corolla. Liliaceae is tricarpellary with undifferentiated tepals (NCERT Biology Lab Manual Class 11, Exercise 11, pages 64–65). Since axile placentation is shared by both families, only carpel number and perianth structure can settle which one a bicarpellary, calyx-and-corolla flower belongs to — here, Solanaceae.
Why B is wrong: B is wrong because Fabaceae has marginal (not axile) placentation, so axile placentation is not what separates Fabaceae from the other two — and it is shared by Solanaceae and Liliaceae, so it is not unique to Liliaceae. (trap: assuming a shared feature is exclusive to one family)
Why C is wrong: C is wrong because a bicarpellary ovary does not automatically mean marginal placentation — Solanaceae itself is bicarpellary with axile placentation, per NCERT Class 11 Biology Chapter 5, page 69. Marginal placentation is specifically tied to Fabaceae's monocarpellary condition. (trap: inventing a carpel-number-to-placentation rule that does not exist)
Why D is wrong: D is wrong because gamopetalous corolla and epipetalous stamens are exactly the Solanaceae condition described on NCERT page 69 — they do not rule Solanaceae out; Fabaceae has a diadelphous, not epipetalous, androecium. (trap: misapplying Solanaceae's own diagnostic features to eliminate it)
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Given
A NEET question presents a plant with: zygomorphic flower, papilionaceous corolla with vexillary aestivation, diadelphous stamens (9)+1, monocarpellary superior ovary, marginal placentation. The question asks to identify the family.
Required
Identify the plant family based on the combination of floral characters.
Concept
Each angiosperm family has a diagnostic combination of floral features. The key is matching ALL features simultaneously — no single feature is sufficient because families can share individual characters.
Formula/Rule
Diagnostic matrix:• Fabaceae: zygomorphic + vexillary + diadelphous + monocarpellary + marginal + legume• Solanaceae: actinomorphic + valvate/twisted + epipetalous + bicarpellary + axile + berry/capsule• Liliaceae: actinomorphic + tepals (P3+3) + 6 free stamens + tricarpellary + axile + capsule/berry
Substitution/Matching
Given features → checklist:• Zygomorphic ✓ → eliminates Solanaceae (actinomorphic) and Liliaceae (actinomorphic)• Vexillary aestivation ✓ → confirms papilionaceous = Fabaceae• Diadelphous (9)+1 ✓ → Fabaceae diagnostic• Monocarpellary + marginal ✓ → Fabaceae (Solanaceae is bicarpellary axile)
Reasoning
All five features align exclusively with Fabaceae. No other family has this combination. The strongest eliminators are symmetry (zygomorphic rules out Solanaceae/Liliaceae immediately) and placentation type (marginal rules out any axile/parietal family).
Final answer
Family: Fabaceae (Papilionaceae)
Common trap
The distractor "Solanaceae" tempts students who focus only on "superior ovary" (shared by all three families) without checking symmetry and placentation. Another trap: confusing "imbricate" with "vexillary" — vexillary IS a type of imbricate, but it's specifically diagnostic for Fabaceae.
Similar NEET-style question
"A plant shows actinomorphic flowers, gamopetalous corolla with 5 epipetalous stamens, bicarpellary syncarpous superior ovary with axile placentation. Identify the family." (Answer: Solanaceae — actinomorphic + gamopetalous + epipetalous + bicarpellary axile is the Solanaceae diagnostic set.)
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Fabaceae (pea): zygomorphic, papilionaceous corolla, marginal placentation, fruit legume. Solanacaeae (potato): actinomorphic, axile placentation, fruit berry/capsule. Liliaceae (onion): trimerous, axile, fruit capsule/berry.
-- NCERT Class 11 Biology, Ch. 5 (not in this chapter of the current NCERT book)More in Structural Organisation in Animals and Plants: 17 exam traps and mistakes · 1 question pattern from its other lessons.
5 questions from NEET 2021, 2022, 2023, 2026. Answers verified against NTA official keys.
Which one of the following plants shows vexillary aestivation and diadelphous stamens?
Diadelphous stamens are found in
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