Giant vallisneria

Vallisneria gigantea

Also known as Giant vals, Jungle val, Vallisneria americana var. gigantea, Vallisneria australis, Tape grass, Eelgrass, Vallisneria 'Gigantea'

FreshwaterBrackishRosetteRunners

Invasive. A vigorous spreader that is invasive in some warm regions. Never release into the wild; dispose of in the trash.

Giant vallisneria (Vallisneria gigantea) — William & Wilma Follette, USDA NRCS, 1992. Western wetland flora: Field office guide to plant species. West Region, Sacramento, CA. Courtesy of USDA NRCS Wetland Science Institute. · Public domain

Care at a glance

Light: Low light
CO2: No CO₂ needed
Growth rate: Fast
Placement: Background
Type: Rosette
Temperature: 64–86°F (18–30°C)
pH: 6.5–8.5
Hardness: 3–20 dGH
Max height: 59.1 in (150 cm)
Spread: 11.8 in (30 cm)
Nutrient uptake: Root feeder
Growth region: Submersed
Difficulty: Beginner
Origin: Asia (genus pantropical); plants in the trade are often Vallisneria americana var. gigantea
Family: Hydrocharitaceae

Overview

A background plant for tall tanks only, since the strap leaves grow 50 to 150 cm long and will carpet the surface in a shorter aquarium. Plant the crown in the substrate but keep the white base of the crown above the gravel or it can rot. It is a heavy root feeder, so root tabs in a nutritious substrate matter far more than water column dosing, and it does fine in low light with no CO2. It spreads fast by runners and forms dense thickets, so thin runners regularly or it will take over and shade out neighbors.

In the wild

Vallisneria is a pantropical genus of submersed, dioecious freshwater herbs found in slow rivers, lakes and ponds across Asia, Australia and the Americas. Giant vallisneria grows fully submersed in soft to hard, often hard alkaline water, rooting in mud or sand and pushing ribbon leaves up to the surface. The trade name covers several large-leaved forms, and much of what is sold as V. gigantea is actually V. americana var. gigantea.

Good to know

Member of the Hydrocharitaceae and dioecious, meaning male and female flowers grow on separate plants. Female flowers reach the surface on long coiled stalks where they are pollinated by free-floating male flowers released from the parent, then the stalk coils back down to ripen the seed underwater. Taxonomy is muddled: the name V. gigantea has been misapplied to both V. australis and the giant variety of V. americana.

Did you know

Did you know the female flower hits the surface on a long spiral stalk, and after pollination the stalk corkscrews back down to mature the seed underwater. Because Vallisneria is sensitive to liquid carbon products, dosing Excel-type glutaraldehyde supplements can melt the leaves while leaving most other plants unharmed.