Question
Differentiate between racemose and cymose inflorescence. Give the types and examples of each.
Solution — Step by Step
flowchart TD
A[Inflorescence] --> B[Racemose - Indeterminate]
A --> C[Cymose - Determinate]
B --> B1[Main axis grows indefinitely]
B --> B2[Flowers open from base to apex]
C --> C1[Main axis terminates in a flower]
C --> C2[Flowers open from apex to base]
B --> D[Raceme: Mustard]
B --> E[Spike: Amaranthus]
B --> F[Corymb: Candytuft]
B --> G[Umbel: Coriander]
B --> H[Capitulum: Sunflower]
C --> I[Monochasial: Jasmine]
C --> J[Dichasial: Teak]
C --> K[Polychasial: Calotropis]The main axis continues to grow indefinitely — it does NOT terminate in a flower. Flowers are borne laterally. The oldest flowers are at the base, youngest at the tip. The order of flowering is acropetal (bottom to top). Types include: Raceme (mustard — flowers on pedicels along an elongated axis), Spike (Amaranthus — sessile flowers), Corymb (Candytuft — stalks of different lengths so flowers appear at the same level), Umbel (coriander — flower stalks arise from the same point), Capitulum/Head (sunflower — sessile flowers on a flat receptacle).
The main axis terminates in a flower, stopping its growth. Further flowers develop from lateral branches. The oldest flower is at the centre/top, youngest at the periphery. The order of flowering is basipetal (top to bottom). Types: Monochasial (one lateral branch per node — scorpioid cyme in jasmine), Dichasial (two lateral branches per node — teak, Dianthus), Polychasial (multiple branches per node — Calotropis).
Cyathium (Euphorbia) — a single female flower surrounded by male flowers, all enclosed in a cup-shaped involucre. Looks like a single flower but is actually an inflorescence. Hypanthodium (Ficus/fig) — flowers borne on the inner wall of a fleshy, hollow receptacle.
Why This Works
| Feature | Racemose | Cymose |
|---|---|---|
| Main axis growth | Indefinite (indeterminate) | Terminates in a flower (determinate) |
| Oldest flower | At the base | At the centre/top |
| Flowering order | Acropetal (base to tip) | Basipetal (centre outward) |
| Examples | Mustard, sunflower, amaranthus | Jasmine, teak, Calotropis |
Common Mistake
Students often misidentify the sunflower head as a single flower. The sunflower “flower” is actually a capitulum (head) — a type of racemose inflorescence. It consists of hundreds of tiny florets: ray florets (outer, petal-like, sterile) and disc florets (inner, fertile, producing seeds). Each “seed” of a sunflower comes from one disc floret.