The correct sequence of plants in a hydrosere is

Options

A. (a) Pistia `rarr` Volvox `rarr` Scirpus `rarr` Hydrilla `rarr` Oak `rarr` Lantana
B. (b) Oak `rarr` Lantana `rarr` Volvox `rarr` Hydrilla `rarr` Pistia `rarr` Scirpus
C. (c) Oak `rarr` Lantana `rarr` Scirpus `rarr` Pistia `rarr` Hydrilla `rarr` Valvax
D. (d) Volvox `rarr` Hydrilla `rarr` Pistia `rarr` Scirpus `rarr` Lantana `rarr` Oak

Answer

To answer the question regarding the correct sequence of plants in a hydrosere, we need to understand the stages of plant succession that occur in freshwater bodies such as lakes and ponds. Here’s a step-by-step breakdown of the sequence:

### Step-by-Step Solution:

1. **Understanding Hydrosere**:
- A hydrosere is a type of ecological succession that occurs in aquatic environments, specifically in freshwater bodies like lakes and ponds. It involves the gradual transition from an aquatic ecosystem to a terrestrial ecosystem.

2. **First Stage - Phytoplankton**:
- The initial stage of a hydrosere is dominated by **phytoplankton**. These are microscopic plants that float in the water and are primary producers in aquatic ecosystems.

3. **Second Stage - Submerged Plants**:
- The next stage involves **submerged plants** such as **Hydrilla** and **Valisneria**. These plants grow beneath the water surface and are rooted in the sediment.

4. **Third Stage - Submerged or Free-Floating Plants**:
- Following the submerged plants, we have the **submerged or free-floating plant stage**. Examples include **Wolffia** and **Pistia**, which can float on the water surface without being anchored to the bottom.

5. **Fourth Stage - Reed Swamp**:
- The next stage is the **reed swamp**, characterized by plants like **Scirpus** and **Typha**. These plants grow at the water's edge and can tolerate both wet and dry conditions.

6. **Fifth Stage - Marsh Meadows**:
- The **marsh meadow stage** follows, where plants such as **Cypress** and **Lantana** grow. These plants are found in areas that are partially submerged and have high moisture content.

7. **Sixth Stage - Woodland**:
- The next stage is the **woodland stage**, where trees such as **Populus** and **Oak** begin to establish themselves as the soil dries out and becomes more suitable for terrestrial plants.

8. **Climax Community**:
- Finally, the hydrosere reaches its **climax community**, which is a fully developed forest ecosystem with a diverse range of trees, shrubs, herbs, and microorganisms living in harmony.

### Correct Sequence of Plants in a Hydrosere:
- **Phytoplankton** → **Hydrilla** (Submerged Plant) → **Pistia** (Submerged or Free-Floating Plant) → **Scirpus** (Reed Swamp) → **Lantana** (Marsh Meadows) → **Oak** (Woodland)

Based on the above analysis, the correct answer is **Option D**.