Hydrilla verticillata Care Guide
Hydrilla verticillata is a vigorous oxygenator with whorled serrated leaves; it is invasive and legally restricted in many regions.
Overview
Hydrilla verticillata is a submerged stem plant in the family Hydrocharitaceae and the only species in the genus Hydrilla. It bears whorled, serrated leaves and is among the fastest-growing aquatic plants, reproducing by stem fragments, turions and tubers.
Taxonomy
- Family: Hydrocharitaceae
- Genus: Hydrilla (monotypic)
- Scientific name: Hydrilla verticillata
- Common synonyms: Hydrilla, waterthyme
Habitat
The species is native to the cool and warm waters of the Old World across Asia, Africa and Australia, with a scattered natural distribution. Stems reach up to 2 m, with leaves 5-20 mm long and 0.7-2 mm broad arranged in whorls of two to eight. It can grow to the surface and form dense mats.
Aquarium requirements
- Placement: background
- Temperature: 16-30 °C (61-86 °F)
- pH: 6-8
- GH: 4-18 °dGH
- Lighting: low to high
- CO2: not required (responds to 5-40 mg/L)
- Maximum height: about 80 cm
Growth and care
Hydrilla is rated very easy and grows extremely fast, in field conditions up to about 2.5 cm per day. It tolerates a wide light range and is an efficient oxygenator and nutrient remover. Frequent trimming, roughly every ten days, is needed to keep it under control. The plant cannot grow emersed.
Propagation
It propagates readily from cuttings and fragments, and in nature also from turions (overwintering buds) and tubers, which is part of why it is so persistent.
Notes on invasiveness
Introduced to the United States via the aquarium trade in the mid-20th century, Hydrilla is now widespread and is regarded as one of the most serious aquatic weeds in Florida and much of the US. It is allelopathic toward some hornworts. Import, sale and possession are restricted in many regions.