Hydrilla

Description

Hydrilla, also known as waterthyme, is an aquatic plant that belongs to the Hydrocharitaceae family. It is native to Asia, Africa, and Australia but has been introduced to other parts of the world, including North America, Europe, and South America. It is considered an invasive species in many countries, causing harm to native ecosystems.

Taxonomic Information

Appearance

Hydrilla has slender stems that can grow up to 25 feet long. The leaves are small, around 1/8 inch wide and up to 1 inch long, and arranged in whorls of 4-8. The plant can have both submersed and floating leaves, with the latter being oval-shaped and up to 1/2 inch long. The roots are fine and hair-like, and can be up to 2 feet long. The plant’s appearance can vary depending on the water depth and nutrient availability.

Care Guide

Hydrilla does not require much care as it can grow rapidly in favorable conditions. However, to prevent its spread and protect native ecosystems, it is important to control its growth. Here are some tips:

• Water: Hydrilla prefers slow-moving or still water, but can also grow in fast-moving water.
• Fertilization: Avoid fertilizing the water where Hydrilla is present, as it can promote its growth.
• Soil: N/A (Hydrilla grows in water)
• Sunlight: Hydrilla can grow in both full sun and shade.
• Hardiness Zones: Hydrilla is tolerant of a wide range of temperatures and can grow in zones 4-11.

Common Pests & Diseases

Hydrilla can be affected by several pests and diseases, including:

• Hydrilla leaf-mining midge (Cricotopus lebetis): Larvae of this insect feed on the leaves, causing them to turn brown and die.
• Hydrilla tuber weevil (Bagous hydrillae): The larvae of this weevil feed on the tubers, causing them to rot and reducing the plant’s ability to grow.
• Fungal infections: Hydrilla can be affected by several fungal infections, including Myrothecium and Rhizoctonia.

Habitat

Hydrilla can grow in a variety of aquatic habitats, including lakes, rivers, ponds, and canals. It prefers slow-moving or still water and can tolerate a wide range of temperatures. Hydrilla can grow in both freshwater and brackish water, but does not tolerate high salinity levels.

Question and Answer

Q: Is Hydrilla harmful to native ecosystems?
A: Yes, Hydrilla is considered an invasive species in many countries and can harm native ecosystems by outcompeting native plants, reducing water quality, and altering aquatic habitats.

Q: Can Hydrilla be controlled?
A: Yes, Hydrilla can be controlled using several methods, including manual removal, herbicides, and biological control agents.

Q: Can Hydrilla be beneficial?
A: In some cases, Hydrilla can be beneficial as it can provide habitat for fish and other aquatic animals.

Q: Can Hydrilla be eaten?
A: Yes, Hydrilla is edible and is used as a food source in some countries, including China and India.

Related Plants

• Elodea
• Egeria
• Vallisneria
• Cabomba

References

• “Hydrilla verticillata.” USDA Plants Database.
• “Hydrilla.” Center for Aquatic and Invasive Plants, University of Florida.
• “Hydrilla.” National Park Service.