Question

An example of plant that lives in water is
A. Opuntia
B. Hydrilla
C. Touch- me-not
D. Calotropis

Answer 1

Plants that grow in water are called aquatic plants. Many plants can survive in water, both saltwater and freshwater. The plants that live near the water bodies are also called water plants. They may be floating, submerged, or emergent in water. The abnormal increase in the number of water plants can lead to water pollution and a decrease in the amount of dissolved oxygen in the water.

Complete answer:

Hydrilla or water thyme is a water plant under angiosperms. Flowers are rarely seen in them. It is an invasive plant and is regarded as an aquatic weed. The leaves of Hydrilla are arranged as whorls. They are highly resistant to saltwater, unlike other freshwater plants. Usually a single species Hydrilla verticillata is observed. They can be found in both cool and warm water bodies. They are highly adaptive and invasive. It is a very competitive species that competes and displaces the indigenous species of water plants of an area. They have become monocultures in a large aquatic area disrupting the normal equilibrium in the water life. It contains several antioxidants and minerals. It can inhibit the growth of hornworts.
Opuntia is called the prickly pear coming under the cactus family, Cactaceae. They are actually native to America but have now spread to different continents. They are highly resistant to extreme temperatures. They produce a fruit called tuna which is edible. They can be seen in sandy regions. The introduction of prickly pear cactus into Australia in the early 1920s caused havoc by spreading rapidly into a large area. It becomes an invasive weed in Australia which was later controlled by introducing a cactus feeding moth from its natural habitat.
Touch-me-not plant or Mimosa pudica is a ground plant and not a water plant. They are known for its seismonastic responses which are its quick response when coming into contact with anything. It is not so invasive and not a troubling plant.
Calotropis is a flowering plant that produces a milky secretion giving it the name milkweed. It is a poisonous plant that produces many poisonous phenolic compounds in it which can affect the animals eating it. The plant also has medicinal properties.

The correct answer is option (B), Hydrilla.

Note: Water plants have special adaptations for its survival like floating, thin leaves, large air-filled cavities in the stem, etc. Hydrilla is a water plant which is a very invasive plant. Opuntia is a ground plant which is also an invasive plant. Both of the plants can spread into a vast area, becoming environmental havoc replacing the native vegetation of the area. These are invasive weeds that are controlled by biological weapons.