Question
Differentiate between racemose and cymose inflorescence. Name the subtypes of each with examples.
Solution — Step by Step
An inflorescence is the arrangement of flowers on the floral axis (peduncle). Instead of producing flowers singly, many plants group them — this increases visibility to pollinators and improves reproductive success.
In racemose (indefinite) inflorescence, the main axis continues to grow indefinitely, producing lateral flowers. Older flowers are at the base; younger ones at the tip. The main axis never terminates in a flower.
| Subtype | Description | Example |
|---|---|---|
| Raceme | Flowers on pedicels along main axis | Mustard (sarson), radish |
| Spike | Sessile flowers (no pedicels) | Amaranthus, wheat |
| Spadix | Spike with fleshy axis, enclosed in spathe | Banana, Arum lily |
| Corymb | Lower flowers have longer pedicels, flat-topped | Candytuft (Iberis) |
| Umbel | Flowers arise from same point on axis | Carrot, coriander |
| Capitulum (Head) | Sessile flowers packed on flat receptacle | Sunflower, marigold |
In cymose (definite) inflorescence, the main axis terminates in a flower. Further growth is from lateral branches, which also end in flowers.
| Subtype | Branching Pattern | Example |
|---|---|---|
| Monochasial (Uniparous) | One lateral branch per node | Jasmine |
| Dichasial (Biparous) | Two lateral branches per node | Bougainvillea, Jasmine |
| Polychasial (Multiparous) | Multiple branches per node | Calotropis |
flowchart TD
A[Inflorescence Types] --> B[Racemose - Indefinite]
A --> C[Cymose - Definite]
B --> B1[Main axis grows indefinitely]
B --> B2[Older flowers at base]
B --> B3[Raceme, Spike, Spadix, Umbel, Capitulum]
C --> C1[Main axis ends in a flower]
C --> C2[Younger flowers at base]
C --> C3[Monochasial, Dichasial, Polychasial]Why This Works
The fundamental difference is about growth pattern of the main axis. If the axis has no terminal flower and keeps elongating — racemose. If it ends in a flower and growth shifts to lateral branches — cymose. This single criterion separates the two.
Alternative Method
Some books classify inflorescences as mixed when both racemose and cymose patterns appear in the same plant. For example, in some species, the main axis is racemose but each branch terminates cymosely. For NEET, stick to the NCERT classification: racemose vs cymose.
Common Mistake
Students confuse a capitulum with a single flower. The sunflower “head” is actually an inflorescence — it contains dozens of tiny disc florets (centre) and ray florets (periphery). Each “petal” you see is actually a separate ray floret. This is a common NEET trap question.
Remember the key difference with direction: In racemose, flowering order is acropetal (base to tip) or centripetal (outside to centre). In cymose, it is basipetal (tip to base) or centrifugal (centre to outside).