What is characteristic of a liana

Options

A. Soft herbaceous stem
B. Alternate vertical parenchyma strands
C. Heavy foliage
D. Central cavity.

Answer

### Step-by-Step Solution:

1. **Definition of Lianas**: Lianas are woody climbers found primarily in tropical rainforests. They are characterized by their ability to climb on other trees to reach sunlight.

2. **Woody Structure**: Unlike soft herbaceous plants, lianas have a hard outer surface, which provides them with the strength needed to climb and support themselves as they grow upwards.

3. **Climbing Mechanism**: Lianas utilize clinging roots to attach themselves to other trees. This adaptation allows them to ascend towards the canopy where sunlight is more abundant.

4. **Sunlight Access**: In the dense environment of tropical rainforests, the lower levels receive limited sunlight. By climbing on taller trees, lianas can access more light for photosynthesis.

5. **Parenchyma Strands**: One of the key characteristics of lianas is the presence of alternate vertical parenchyma strands. These strands provide structural support, enabling the lianas to grow tall and climb effectively.

6. **Foliage and Central Cavity**: Lianas do not typically have heavy foliage, as this would hinder their ability to climb. Additionally, they lack a central cavity, which is common in some other climbing plants.

7. **Conclusion**: The characteristic feature of lianas is the presence of alternate vertical parenchyma strands, which support their climbing habit.