Q.Many pulses of daily use belong to one of the families below (tick the correct answer)
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The Pea Family: Fabaceae
You already know a pea pod. You've seen the little green beads lined up inside, each one attached along one edge. That single image — a row of seeds inside a pod — is the entire story of this family in miniature. Everything else is just decoration.
The Intuition
Think about what a pea plant does. It climbs. It fixes nitrogen from the air into the soil. It produces a fruit that splits open along two seams to release its seeds. The flower that makes that fruit looks like a tiny butterfly — one big petal on top, two side petals, and two lower petals fused together into a little boat.
That flower shape is not random. It's a landing pad for bees. The big top petal is a flag. The side petals are wings. The boat-shaped bottom holds the stamens and pistil. When a bee lands, its weight pushes the boat down, and the stamens spring up to dust it with pollen. The bee visits the next flower, and the pollen transfers. That is the entire evolutionary logic of the pea flower.
Now the precise biology.
Vegetative Features
The plants are herbs, shrubs, or climbers. Leaves are compound — divided into leaflets — and almost always have stipules (small leaf-like structures at the base of the leaf stalk). Many species have tendrils (modified leaflets that coil around supports). The stem is often hollow in herbs.
The tendril in pea is a modified leaflet, not a modified stem. This is a common exam point.
Floral Features — The Diagnostic Set
The flower is zygomorphic (bilateral symmetry — only one plane cuts it into mirror halves). This is the key contrast with radially symmetrical flowers like those of the mustard family.
The calyx has 5 sepals, fused together (gamosepalous). The corolla has 5 petals arranged in a very specific way called papilionaceous — from the Latin for butterfly.
Memorise the petal names: Vexillum (standard) — the large top petal. Alae (wings) — the two side petals. Carina (keel) — the two bottom petals fused together, shaped like a boat's keel.
The androecium has 10 stamens. They are diadelphous — 9 fused into a tube and 1 free. This is the single most reliable diagnostic character for the family.
The gynoecium has one carpel (monocarpellary). The ovary is superior. Placentation is marginal — the ovules are arranged in a row along the fused edge of the single carpel. This is what gives you that row of peas inside the pod.
Family Fabaceae — Diagnostic Formula
Flower: Zygomorphic, bisexual
Calyx: 5, gamosepalous
Corolla: 5, polypetalous, papilionaceous (vexillum, alae, carina)
Androecium: 10, diadelphous (9+1)
Gynoecium: 1 carpel, superior ovary, marginal placentation
Fruit: Legume (pod)
The Fruit …
Common pulses used daily, such as gram, pea, moong and similar legumes, belong to the plant family that is characterised by features like a papilionaceous, vexillary corolla with a large standard petal overlapping two wing petals, which in turn overlap the two keel petals, and stamens that are typically united into two bundles, a condition called diadelphous, as seen in pea. These floral features, along with a single carpel giving a superior, monocarpellary ovary, are hallmar …
Everyday pulses such as gram and pea belong to Fabaceae, recognisable by their papilionaceous flowers and diadelphous stamens.
Several distinguishing floral features described for pea and related plants point directly to this family.
- The corolla of such flowers shows vexillary, or papilionaceous, aestivation, in which the largest of the five petals, the standard, overlaps the two lateral wing petals, which in turn overlap the two smallest, anterior keel petals.
- The stamens of these flowers are often united into two bundles rather than remaining completely free or fusing into a single bundle, a condition described as diadelphous, with pea given as the example. …
Method: Work Backward From a Familiar Flower You Already Know
Instead of recalling "pulses belong to Fabaceae" as an isolated fact, reconstruct the answer by picturing a pea flower, a plant everyone can visualise, and matching its known features to the family description.
Step 1: picture a pea flower. Recall its shape, one large upright petal at the back, two side petals like wings, and two lower petals fused into a boat shape. This is the papilionaceous, or vexillary, form.
Step 2: recall that pea's stamens are grouped into two bundles, diadelphous, and it has a single carpel forming a pod that splits open along two seams, exactly the pod seen in real peas and beans at home.
Step 3: since gram, pea, moong and other everyday pulses share this same recognisable pod-and-butterfly-flower body plan, they must all belong to the same family as pea.
Step 4: recall which family this pea-type flower defines, Fabaceae, the pea family. …
- AP EAPCET 2023Set ap-2023-05-22-AN1 markMCQQ.Choose the correct statement related to the morphology of Cassia (A) Valvate aestivation, Actinomorphic, corymb (B) Imbricate aestivation, zygomorphic, corymb (C) Imbricate aestivation, zygomorphic, umbel (D) Valvate aestivation, zygomorphic, umbel
›Reveal solutionSolution
Cassia (Caesalpinioideae) has imbricate aestivation, a zygomorphic flower, and a corymbose inflorescence — matching option (B).
Concept and Intuition
Family Fabaceae is divided into three sub-families with characteristic floral differences: Papilionoideae (strongly zygomorphic, papilionaceous, vexillary aestivation), Caesalpinioideae (Cassia, Gulmohar — imbricate aestivation, zygomorphic but not as strongly bilateral), and Mimosoideae (valvate aestivation, actinomorphic, small flowers in globose heads). Cassia is the textbook Caesalpinioideae example.
Step-by-Step Solution
- Aestivation in Caesalpinioideae (Cassia) is imbricate — petals overlap each other without a fixed order.
- Symmetry: the Cassia flower is zygomorphic (bilaterally symmetric), though less strongly so than a true papilionaceous flower.
- Inflorescence: Cassia's flowers are arranged in a flat-topped, corymb-like raceme. …
- AP EAPCET 2022Set ap-2022-07-11-AN1 markMCQQ.Some plants of the following family have swollen leaf base (A) Leguminosae (B) Asteraceae (C) Malvaceae (D) Lilliaceae
›Reveal solutionSolution
A swollen leaf base (pulvinus) is a characteristic morphological feature of many plants in family Leguminosae (Fabaceae), distinguishing it from Asteraceae, Malvaceae and Liliaceae in this context.
Concept and Intuition
Leaf morphology varies characteristically across plant families, and one of the diagnostic features taught for family Leguminosae (Fabaceae) is that the base of the leaf (or leaflet) is often swollen into a cushion-like structure called the pulvinus. This swelling is not just a passive structural feature — it contains motor cells that can change turgor pressure, enabling reversible leaf/leaflet movements, most dramatically seen in the sensitive plant Mimosa pudica, whose leaflets fold rapidly upon touch due to pulvinus action. This swollen-leaf-base feature is specifically taught as characteristic of the pea/bean family in the plant morphology chapter.
Step-by-Step Solution …
- AP EAPCET 2022Set ap-2022-07-11-AN1 markMCQQ.Choose the correct one related to Arachis I) Indehiscent fruit II) Monadelphy III) Non-endospermic seed IV) Geocarpy V) Dehiscent fruit (A) I , IV only (B) II, IV, V (C) I, II, V (D) I, II, III, IV
›Reveal solutionSolution
Groundnut (Arachis) is famous for a cluster of exceptional traits — indehiscent fruit, monadelphous stamens, non-endospermic seed and geocarpy — all four of which are correct together.
Concept and Intuition
Arachis is repeatedly tested because it breaks several "typical legume" rules and adds the unusual phenomenon of geocarpy (fruit ripening underground), which itself explains why its pod stays unopened (indehiscent) — an exposed, splitting pod underground would be pointless/harmful.
Step-by-Step Solution
- Fruit type: after fertilization in the aerial flower, the peduncle (the "peg") elongates and bends downward, burying the developing ovary in the soil — this underground fruit development is geocarpy (statement IV, true).
- Because the pod matures buried in soil, it does not need to split open to disperse seeds by wind/animals — it stays closed: indehiscent fruit (statement I, true; statement V, dehiscent, false).
- Stamens: unlike most Papilionaceae (Fabaceae) which are diadelphous (9 fused + 1 free), Arachis is an exception with all 10 stamens fused into a single bundle — monadelphous (statement II, true). …
- AP EAPCET 2021Set ap-2021-10-05-FN1 markMCQQ.The pulvinate leaf base is present in ________ (A) Gloriosa superba (B) Glycine max (C) Allium cepa (D) Solanum tuberosum
›Reveal solutionSolution
A swollen (pulvinate) leaf base is characteristic of legumes; Glycine max (soybean, family Fabaceae) is the matching example among the options.
Concept and Intuition
Certain plants show a swollen, pad-like structure at the base of the leaf or leaflet called a pulvinus, which enables movements such as leaf-folding or reorientation in response to touch or light (e.g., in the touch-me-not plant, or the day/night leaflet movements of many legumes). This pulvinate leaf base is a well-known family-level character of Fabaceae (Leguminosae/pea family).
Step-by-Step Solution
- Recall which plant family is classically associated with a pulvinate leaf base: Fabaceae (legumes), e.g., Pisum sativum (pea).
- Among the given options, identify the Fabaceae member: Glycine max (soybean) belongs to Fabaceae. …
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