Question
Differentiate between taproot and fibrous root systems. List the modifications of roots with examples for each.
(NEET + CBSE Class 6 and Class 11)
Solution — Step by Step
| Feature | Taproot | Fibrous root |
|---|---|---|
| Structure | One main root with lateral branches | Many thin roots of similar size |
| Found in | Dicots (mango, neem, mustard) | Monocots (wheat, rice, grass) |
| Depth | Grows deep into soil | Spreads horizontally near surface |
| Seed type | From dicot seeds (two cotyledons) | From monocot seeds (one cotyledon) |
| Modified root | Example | What it stores |
|---|---|---|
| Fusiform (spindle-shaped) | Radish | Food (starch) |
| Conical (cone-shaped) | Carrot | Food (starch) |
| Napiform (turnip-shaped) | Turnip, beetroot | Food (starch) |
| Tuberous | Sweet potato | Food (starch) |
These are all taproot modifications that store food for the plant’s use during unfavourable seasons.
| Modification | Function | Example |
|---|---|---|
| Prop roots | Support (grow from stem/branches into soil) | Banyan tree |
| Stilt roots | Support in marshy areas | Maize, sugarcane |
| Pneumatophores | Breathing (grow upward for aeration) | Rhizophora (mangrove) |
| Parasitic roots (haustoria) | Absorb nutrients from host | Cuscuta (amarbel) |
| Nodulated roots | Nitrogen fixation (house Rhizobium bacteria) | Pea, bean (legumes) |
Root Modification Classification Tree
flowchart TD
A["Root Systems"] --> B["Taproot — dicots"]
A --> C["Fibrous — monocots"]
B --> D["Modifications for storage"]
B --> E["Modifications for support"]
D --> D1["Fusiform: Radish"]
D --> D2["Conical: Carrot"]
D --> D3["Napiform: Turnip"]
D --> D4["Tuberous: Sweet potato"]
E --> E1["Prop roots: Banyan"]
E --> E2["Pneumatophores: Mangrove"]
C --> F["Stilt roots: Maize"]
C --> G["Nodulated: Legumes"]Why This Works
Roots are modified to serve functions beyond absorption — storage, support, aeration, and even parasitism. Each modification is an evolutionary adaptation to the plant’s environment.
Mangroves grow in waterlogged soil with low oxygen, so they develop pneumatophores that grow upward to breathe. Banyan trees have massive canopies that need extra support, so prop roots descend from branches to the ground.
Common Mistake
Students confuse sweet potato (root modification) with potato (stem modification). Sweet potato is a tuberous root — it does not have eyes (buds). Potato is a stem tuber — it has eyes (buds) on its surface. This is a classic NEET question. If it has buds/eyes, it is a stem. If it does not, it is a root.