Hydrilla, Waterthyme
Hydrilla verticillata
Family: Hydrocharitaceae
What it is like
Hydrilla verticillata is a ANNUAL/PERENNIAL at a fast rate. See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from May to October, and the seeds ripen from June to October. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Water. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: neutral and basic (mildly alkaline) soils and can grow in very alkaline soils. It cannot grow in the shade. It can grow in water.
Height (m): 0
Where it is found
Grows in a variety of aquatic habitats, from acidic to basic, oligotrophic to eutrophic, fresh to brackish, and from a few centimeters deep to a meter or more if light penetrates that deeply.
A cosmopolitan plant, it is hard to know the areas where it is truly native..
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 0
Medicine
Rating: 2
Used in the treatment of abscesses, boils and wounds, especially if there is debris in the wound. A dried powder of the plant is applied to cuts and wounds to help accelerate healing.
Detergent: A cleansing agent, used on wounds etc. It removes dead and diseased matter.
Miscellany: Various medicinal actions that need more clarification.
Other
Rating: 0
The plant is used in sugar refinery. No more details are given.
Miscellany: A rag-bag of items that are difficult to categorise.
How it is grown
A submerged water plant, it prefers growing in alkaline water. A good oxygenator for ponds, the plant forms a large mass with stems up to 2 metres long. This is a very vigorous species which can regrow from even small sections of the plant. Stem fragments become rooted by fine, unbranched adventitious roots and soon produce vegetative reproductive structures from both subterranean and erect stems. Tubers produced on subterranean stems are pale brown; those produced on erect stems are dark olive-green and covered with short, stiff scales. Both types germinate quickly to produce new stems. This species has often invaded native habitats, clogging waterways and crowding out native species of flora and fauna. It is considered a noxious weed in many areas. Plants can be monoecious or dioecious. Dioecious plants (usually female) are triploid forms whilst monoecious plants are diploid. Male flowers are released from the plant under water. They float to the surface where they release their pollen to fertilize female flowers.
Propagating it: Seed - it is quite likely that seed must be kept moist in order to maintain viability. If seed can be obtained, it is probably best sown immediately in a greenhouse in soil covered with water. Tubers - plant immediately in soil covered in water, Division - even small sections of stem will soon start producing roots when placed in water.
Best place to grow: Pond;
Habit: Annual/Perennial
Hardiness: 4-8
Growth: Fast
Soil: Light (sandy), medium, heavy (clay)
Shade: No shade
Moisture: Water