The hydrilla plant is a small aquatic plant. The small size of this plant is easy to handle in the labs during experiments. The plants have features that help them to survive in aquatic life and they can produce oxygen in the water. Hydrilla is a submerged aquatic plant with no stomata to receive carbon dioxide and release oxygen, instead, it breathes through its entire body surface and releases oxygen through this, allowing us to see the oxygen in the form of bubbles, something we cannot see in terrestrial plants. But the land plants cannot produce oxygen through the body.  The land plants use stomata for gas exchange.