Q.Flowers are unisexual in:
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Inflorescence Types
What is an Inflorescence?
Imagine a mango tree in full bloom. You don't see one giant flower — you see hundreds of small flowers arranged along a branch. That arrangement — the pattern in which flowers are born on the flowering shoot — is the inflorescence.
The key question is simple: Where does the main growing tip go?
If the main tip keeps growing and producing new flowers, you get one kind of pattern. If the main tip itself turns into a flower and stops growing, you get a completely different pattern. That single difference is the entire foundation of inflorescence classification.
The Two Fundamental Types
Racemose (Indeterminate) Inflorescence
The main axis (called the peduncle) keeps growing indefinitely. Flowers keep appearing from the sides (axils), while the tip remains active. The oldest flowers are at the base, the youngest at the tip.
Think of a candle — the flame (growing tip) stays at the top, and wax drips down the sides. The tip never becomes a flower itself.
In racemose inflorescence, the main axis does not terminate in a flower. It continues to grow.
Examples you already know:
- Raceme: A central stalk with stalked flowers — like mustard, radish. The oldest flowers are at the bottom.
- Spike: Like a raceme, but flowers are stalkless (sessile) — like wheat, barley.
- Corymb: Lower flowers have longer stalks, so all flowers reach roughly the same height — like candytuft.
- Umbel: All flower stalks arise from the same point at the top of the axis — like onion, coriander.
- Head (Capitulum): A flattened axis with many tiny flowers packed together — like sunflower, marigold.
Cymose (Determinate) Inflorescence
Here, the main axis ends in a flower. That flower blooms first, and the axis stops growing. New flowers arise from side branches below it. The oldest flower is at the top/center, the youngest at the bottom/periphery.
Think of a firecracker — the first spark (oldest flower) is at the tip, and the flame travels downward.
A common mistake: students think cymose means "flowers arranged in a cyme." It means the growth pattern is determinate — the tip becomes a flower and stops.
Examples:
- Solitary cyme: A single terminal flower — like in poppy or tulip. (Yes, a single flower at the tip of a stem is technically a cymose inflorescence.)
- Dichasial cyme: Two side branches arise below the terminal flower, each ending in a flower — like in jasmine.
- Monochasial cyme: One side branch develops below the terminal flower, giving a zigzag or coiled appearance — like in forget-me-not.
The Critical Difference at a Glance
| Feature | Racemose | Cymose |
|---|---|---|
| Main axis growth | Indefinite (keeps growing) | Definite (ends in a flower) |
| Flower opening order | Oldest at base, youngest at tip | Oldest at tip, youngest at base |
| Tip of main axis | Vegetative (never a flower) | Becomes a flower |
| Overall shape | Often elongated or flat | Often compact or coiled |
Why Does This Matter? …
A cyathium (typical of Euphorbiaceae, e.g. Euphorbia) is a special cup-shaped inflorescence enclosing several reduced, stalked male flowers (each a single stamen) surrounding one central, stalked female flower (a single pistil …
In a cyathium, the male flowers (each reduced to one stamen) and the single central female flower (a single pistil) are both unisexual, unlike the bisexual flowers of a verticillaster, cyme, or thyrsus.
A cyathium is a specialised inflorescence in which a cup-like involucre of fused bracts encloses many male flowers, each reduced to just a single stamen jointed to a pedicel (mimicking a filament), arranged around one central female flower reduced to a single stalked pistil. Because each individual flower has only male or only female parts, both flower types in a cyathium are strictly unisexual.
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- CBSE 2026Set ANNUAL1 markQ.What is the arrangement of flowers on the floral axis called?
›Reveal solutionSolution
The pattern in which flowers are arranged on the peduncle (floral axis) is called inflorescence.
When the shoot apex converts to a reproductive (floral) meristem, it may bear a single flower or, more commonly, a cluster of flowers arranged along the elongated floral axis in a characteristic pattern; this pattern is termed the inflorescence. Broadly, inflorescences are classed as racemose (the main axis continues to grow and produce flowers laterally, so the youngest flowers are near the apex, e.g. raceme, spike, panicle) or cymose (the main axis terminates in …
- CBSE 2025Set ANNUAL1 markMCQQ.Inflorescence axis is called(a) Rachis(b) Pedicel(c) Petiole(d) Peduncle
›Reveal solutionSolution
The main axis of an inflorescence (the stalk of the whole flower cluster) is called the peduncle.
In flowering-plant morphology, when the shoot apex transforms into a reproductive (floral) apex, it either produces a single flower or a group/cluster of flowers arranged on the main axis, this arrangement is called an inflorescence.
- The main stalk that bears the whole cluster of flowers is the peduncle.
- The individual stalk of each flower borne on that axis is the pedicel. …
- CBSE 2024Set ANNUAL1 markMCQQ.Thyrsus is a type of:(a) Special inflorescence(b) Mixed inflorescence(c) Cymose inflorescence(d) Racemose inflorescence
›Reveal solutionSolution
Thyrsus combines a racemose main axis with cymosely-branched lateral branches, which is why it is classified as a mixed (compound) type of inflorescence rather than purely racemose or purely cymose.
Inflorescences are broadly grouped as:
- Racemose — the main axis continues to grow indefinitely, producing flowers laterally in acropetal succession (younger flowers near the tip).
- Cymose — the main axis terminates in a flower early, so growth continues through lateral (definite) branches, in a basipetal-appearing succession.
- Mixed (compound) inflorescences — combine both patterns, typically a racemose main axis bearing cymosely-arranged lateral branches (or vice versa), and special inflorescences with unique structural modifications (e.g. cyathium, hypanthodium, verticillaster). …
- CBSE 2022Set ANNUAL1 markMCQQ.In florescence is found in Peepal.(a) Spadix(b) Spike(c) Cyathium(d) hypenthodium
›Reveal solutionSolution
Ficus (Peepal) bears a hypanthodium inflorescence → (d).
- A hypanthodium is a cup/flask-shaped, hollow receptacle enclosing tiny male, female and neuter flowers, with a small apical pore (ostiole). …
- CBSE 2019Set ANNUAL1 markMCQQ.Cyathium inflorescence is found in:(a) Mango(b) Darcitonia(c) Anjir(d) Euphorbia
›Reveal solutionSolution
A cyathium is a cup-like involucre of fused bracts enclosing one central female flower surrounded by many reduced male flowers — a hallmark of the genus Euphorbia.
In a cyathium, a cup-shaped structure formed by fused bracts (the involucre) bears a single, stalked female flower in its centre, surrounded by numerous highly reduced male flowers (each reduced to essentially a single stamen). This condensed, specialised inflorescence is a defining feature of the family Euphorbiaceae, particularly the genus Euphorbia (e.g., Euphorbia pulcherrima — poinsettia, Euphorbia hirta, Euphor …
- CBSE 2018Set ANNUAL1 markMCQQ.Spike is a type of:(a) Mixed inflorescence(b) Racemose inflorescence(c) Special inflorescence(d) Cymose inflorescence
›Reveal solutionSolution
A spike is a racemose inflorescence with sessile flowers on an unbranched, elongated axis.
Inflorescences are broadly classed as RACEMOSE (the main axis keeps growing and does not end in a flower, so flowers open acropetally - oldest at the base, youngest at the apex) or CYMOSE (the main axis terminates in a flower, so growth stops and flowers open basipetally - youngest at the base). A SPIKE is a classic racemose type: like a raceme, but the flowers are sessile instead of pedicellate (e.g. Achyranthes, Amaranthus). "Special" and "mixed" infl …
- CBSE 2018Set ANNUAL1 markMCQQ.Flowers are unisexual in:(a) Verticillaster(b) Cyathium(c) Cyme(d) Thyrsus
›Reveal solutionSolution
In a cyathium, the male flowers (each reduced to one stamen) and the single central female flower (a single pistil) are both unisexual, unlike the bisexual flowers of a verticillaster, cyme, or thyrsus.
A cyathium is a specialised inflorescence in which a cup-like involucre of fused bracts encloses many male flowers, each reduced to just a single stamen jointed to a pedicel (mimicking a filament), arranged around one central female flower reduced to a single stalked pistil. Because each individual flower has only male or only female parts, both flower types in a cyathium are strictly unisexual.
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