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Botany · Morphology of Flowering Plants

Inflorescence — Racemose vs Cymose

An inflorescence is the arrangement of flowers on the floral axis. NCERT splits all inflorescences into two families on a single criterion: whether the apex of the main axis keeps growing or turns into a flower. That one decision fixes the flowering order — acropetal in racemose, basipetal in cymose — and it is the recurring hook NEET uses for assertion–reason and match-the-column items in Morphology of Flowering Plants.

NCERT grounding

NCERT Class 11 Biology, Chapter 5 (section 5.4, The Inflorescence) defines a flower as a modified shoot in which the shoot apical meristem changes into a floral meristem; internodes do not elongate and the axis gets condensed, so the apex produces floral appendages laterally at successive nodes instead of leaves. The chapter states the rule plainly: a shoot tip that itself transforms into a flower is always solitary, whereas the arrangement of several flowers on a floral axis is the inflorescence.

“Depending on whether the apex gets developed into a flower or continues to grow, two major types of inflorescences are defined — racemose and cymose.” — NCERT Class 11 Biology, §5.4

NIOS (Biology, Shoot System, §7.4) adds the same two-fold scheme and tabulates the classic subtypes — raceme, spike, catkin, spadix, corymb, umbel, capitulum on the racemose side; monochasial, dichasial and multichasial cyme on the cymose side — together with the special forms hypanthodium, cyathium and verticillaster. This page goes deeper on the growth-and-order logic that separates the two families.

Racemose vs cymose: the core split

Everything about inflorescence classification rests on the fate of the apical meristem of the main axis (the peduncle). If that apex stays vegetative and keeps adding new flower-bearing nodes below itself, the axis has indefinite, unlimited growth — this is the racemose condition. If the apex is consumed by being converted into a terminal flower, no further nodes can form beyond it; the main axis growth is definite and limited — this is the cymose condition. Because the apex never flowers in a racemose inflorescence, the oldest, fully open flowers sit at the base and progressively younger buds lie towards the tip. The opposite holds in cymose forms, where the single terminal flower is the first and oldest, and the lateral branches that arise below it flower afterwards.

Racemose vs Cymose — the deciding criteria

Racemose

Acropetal

opening order (oldest at base)

  • Main axis does not end in a flower; it keeps growing
  • Growth of main axis is unlimited / indefinite
  • Flowers borne laterally in acropetal succession
  • Oldest flower at base, youngest near the apex
  • Example: mustard (raceme), sunflower (capitulum)
VS

Cymose

Basipetal

opening order (oldest at apex)

  • Main axis terminates in a flower
  • Growth of main axis is limited / definite
  • Flowers borne in basipetal order
  • Oldest (terminal) flower at apex, younger ones below
  • Example: Solanum, Dianthus, jasmine, Calotropis

The words acropetal and basipetal describe direction of succession, not merely position. Acropetal literally means “towards the apex”: each new flower is added above the previous one, so opening proceeds from base upwards. Basipetal means “towards the base”: the apex flowers first and the sequence runs downwards. NCERT pairs racemose with acropetal and cymose with basipetal as a fixed coupling, and NEET tests precisely this coupling.

Figure 1 Racemose inflorescence and acropetal succession growing apex (no flower) oldest flower (base) acropetal: opening base → apex

Figure 1. Racemose inflorescence (e.g. mustard). The apex remains a growing vegetative bud, so the main axis keeps lengthening. Flowers open acropetally — the oldest at the base, the youngest buds near the indefinitely growing tip.

Solitary vs inflorescence

Before a flower can be part of an inflorescence, it must be borne on an axis along with others. NCERT is explicit that when the shoot tip itself transforms into a flower, that flower is solitary — it stands alone and cannot, by definition, be racemose or cymose. A solitary flower may be terminal (on the apex of the stem) or axillary (in the axil of a leaf). The Solanaceae description in NCERT captures both possibilities in one line: inflorescence “solitary, axillary or cymose as in Solanum.” Recognising that a single flower is not an inflorescence prevents a common mislabelling in match-type questions.

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Major inflorescence types

NCERT recognises exactly two on the apex-fate criterion: racemose (apex grows on) and cymose (apex flowers and stops). Every named subtype falls under one of these.

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Deciding question

Ask only: does the main axis end in a flower? No → racemose, acropetal. Yes → cymose, basipetal.

Racemose types and examples

Within the racemose family, NIOS classifies subtypes by the shape of the main axis and whether the flowers are stalked. The unifying feature stays constant: the axis does not end in a flower and flowers open acropetally. The differences are mechanical — length of the axis, presence or absence of flower stalks (pedicels), and whether the axis is elongated, shortened or flattened.

Read each card as: axis form → flower stalk condition → example. All share an apex that keeps growing (acropetal opening).

Raceme

Elongated axis; flowers stalked (pedicellate), arranged acropetally.

Example: mustard.

Spike

Like a raceme but flowers are sessile (no stalk).

Example: Achyranthes.

Catkin

Like a spike but the axis is pendulous, bearing unisexual flowers.

Example: mulberry.

Spadix

Like a spike but the axis is fleshy, enclosed by a showy bract (spathe).

Example: Colocasia, banana.

Corymb

Shortened axis; lower (older) flowers have longer stalks so all reach one level.

Example: candytuft.

Umbel

Flowers with stalks of equal length arising from the same point.

Example: coriander.

Capitulum (head)

Axis flattened into a receptacle bearing sessile florets in centripetal order, surrounded by an involucre of bracts.

Example: sunflower.

The capitulum deserves special care. In a sunflower “flower” the whole head is the inflorescence: many small sessile florets are packed on a flattened receptacle, opening centripetally (older towards the periphery, younger towards the centre), with the peripheral ray florets carrying inferior ovaries. Treating the head as a single flower is a frequent error.

Cymose types and special forms

In cymose inflorescences the terminal flower forms first; subsequent flowers arise on lateral branches that themselves end in flowers, giving the basipetal sequence. NIOS classifies cymes by how many lateral branches arise below the terminal flower.

Cymose subtypes by number of lateral branches

terminal flower forms first in each
  1. Mono

    Monochasial cyme

    Axis ends in a flower; a single lateral branch arises from one side and again ends in a flower.

    Cotton
  2. Di

    Dichasial cyme

    Two lateral branches develop on either side of the terminal flower; each ends in a flower.

    Dianthus, jasmine
  3. Multi

    Multichasial cyme

    Several lateral branches arise from below the terminal flower; each ends in a flower.

    Calotropis
Figure 2 Cymose (dichasial) inflorescence and basipetal order terminal flower (oldest) youngest flowers (below) basipetal: opening apex → base

Figure 2. Dichasial cyme (e.g. Dianthus, jasmine). The main axis is closed by the oldest terminal flower at the apex; paired lateral branches below bear progressively younger flowers, so opening runs apex → base (basipetal).

NIOS also lists three special types of inflorescence that combine features or modify the receptacle. These appear occasionally in higher-difficulty questions and are worth recognising by example.

Hypanthodium

Fleshy receptacle forms a cup-like cavity with an apical opening; male and female flowers line the inner wall.

Example: fig, peepal.

Cyathium

A cup-shaped involucre encloses a single female flower surrounded by many male flowers; nectary on the rim.

Example: Euphorbia.

Verticillaster

A condensed dichasial cyme at each node, with a cluster of sessile flowers in the leaf axils.

Example: Ocimum (tulsi), Salvia.

Worked examples

Worked example 1

In a racemose inflorescence the flowers open from base to apex. What is the name of this succession, and what does it tell you about the apex of the main axis?

The succession is acropetal (towards the apex). Because the oldest flowers are at the base and younger ones lie higher up, the apex cannot have flowered — it remains a growing vegetative bud, which is exactly why a racemose main axis has unlimited growth and never terminates in a flower.

Worked example 2

A student finds an inflorescence in which the topmost flower is the oldest and fully mature, while flowers lower on the axis are progressively younger. Classify it.

The oldest flower being terminal means the main axis has ended in a flower and stopped growing — this is a cymose inflorescence, with flowers borne in basipetal order. (In NCERT examples this matches Solanum.)

Worked example 3

Why is a sunflower “flower” correctly described as an inflorescence, and to which major type does it belong?

A sunflower head is a capitulum — the main axis is flattened into a receptacle bearing many sessile florets. Since it carries many flowers on a common axis whose apex does not become a single flower, it is an inflorescence, and the capitulum is a racemose type.

Common confusion & NEET traps

NEET PYQ Snapshot — Inflorescence — Racemose vs Cymose

Inflorescence is rarely a standalone stem; it surfaces inside Morphology assertion–reason and figure-ID items. Below: the closest bank questions, plus concept drills.

NEET 2023

Assertion A: A flower is defined as a modified shoot wherein the shoot apical meristem changes to floral meristem. Reason R: Internode of the shoot gets condensed to produce different floral appendages laterally at successive nodes instead of leaves. Choose the correct answer.

  1. A is false but R is true
  2. Both A and R are true and R is the correct explanation of A
  3. Both A and R are true but R is NOT the correct explanation of A
  4. A is true but R is false
Answer: (2)

Why: The flower-as-modified-shoot definition (§5.4) is the basis of the whole inflorescence concept: the floral meristem and condensed internodes produce floral appendages, and whether the apex flowers or grows on then decides racemose vs cymose. Both statements are true and R explains A.

NEET 2024

Identify the correct description about the given figure (an open, exposed spike-like floral axis with prominent stamens).

  1. Wind pollinated plant inflorescence showing flowers with well exposed stamens.
  2. Water pollinated flowers showing stamens with mucilaginous covering.
  3. Cleistogamous flowers showing autogamy.
  4. Compact inflorescence showing complete autogamy.
Answer: (1)

Why: The figure is an inflorescence with exposed stamens — a classic wind-pollinated (anemophilous) arrangement. Reading the axis as an inflorescence, not a single flower, is the step that lets you reject the autogamy options.

Concept

In which inflorescence is the main axis limited in growth, with flowers borne in basipetal order?

  1. Raceme
  2. Cymose
  3. Capitulum
  4. Spike
Answer: (2)

Why: Limited (definite) growth with basipetal order defines a cymose inflorescence — the apex terminates in the oldest flower. Raceme, capitulum and spike are all racemose (acropetal, indefinite axis).

FAQs — Inflorescence — Racemose vs Cymose

The high-yield clarifications NEET aspirants ask most on this subtopic.

What is an inflorescence?

An inflorescence is the arrangement of flowers on the floral axis. A flower is a modified shoot in which the shoot apical meristem changes to a floral meristem; when a shoot tip itself transforms into a flower, that flower is always solitary, but when several flowers are borne on a common axis, the arrangement is called an inflorescence.

What is the main difference between racemose and cymose inflorescence?

In a racemose inflorescence the main axis does not end in a flower and continues to grow, so flowers are borne laterally in acropetal succession (oldest at the base, youngest near the apex). In a cymose inflorescence the main axis terminates in a flower and is limited in growth, so flowers are borne in a basipetal order with the terminal flower being the oldest.

What does acropetal succession mean?

Acropetal succession means flowers open in order towards the apex: the oldest, mature flowers lie at the base of the axis and the youngest buds lie near the growing tip. This is the pattern seen in racemose inflorescences such as that of mustard.

Why is a racemose axis able to keep growing while a cymose axis is not?

In a racemose inflorescence the apical meristem of the main axis stays vegetative and keeps producing new flower-bearing nodes laterally, so growth is indefinite. In a cymose inflorescence the apical meristem is itself converted into the terminal flower, which uses up the growing point, so the main axis growth is definite and limited.

Is a sunflower head a single flower or an inflorescence?

The sunflower head is an inflorescence, not a single flower. It is a capitulum (head), a racemose type in which the main axis is flattened into a receptacle bearing many small sessile florets, with ray florets towards the periphery showing inferior ovaries.

What inflorescence is found in Solanum?

In the family Solanaceae the inflorescence is solitary and axillary, or cymose as in Solanum. A cymose inflorescence has a main axis that ends in a flower and bears flowers in basipetal order.

Related Topics
Morphology of Flowering Plants Back to the full chapter notes. Stem — functions & features The axis from which the floral axis is built. Modifications of stem How shoot axes adapt for support, storage and propagation. Flower parts & symmetry The flower borne on the inflorescence, whorl by whorl. Aestivation & placentation Arrangement of petals in bud and ovules in ovary. Fruit types What the ovaries of an inflorescence mature into. Leaf — parts, venation, phyllotaxy Acropetal leaf arrangement, the vegetative parallel.