Lake Quillwort

Lake Quillwort (Isoetes lacustris) is a primitive, slow-growing aquatic lycophyte (a vascular seedless plant related to clubmosses) native to cool, nutrient-poor (oligotrophic) lakes across Northern Europe and North America.

Name

• Scientific Name: Isoetes lacustris

• Common Names: Lake Quillwort, Merlin's Grass

Characteristics

• Appearance: Dark green, stiff, tubular, quill-like leaves radiating from a central bulbous base (corm).

• Plant Type: Primitive aquatic lycophyte (fern ally) that reproduces via microscopic spores rather than seeds or flowers.

• Special Adaptation: Uses CAM photosynthesis to absorb carbon dioxide ($CO_2$) at night, allowing it to survive in carbon-scarce lakes.

• Sensitivity: Extremely sensitive to algae buildup and pollution; acts as a bio-indicator for water quality.

Temperature

• Ideal Range: 40°F – 68°F (4°C – 20°C)

• Note: Prefers cold water and struggles or dies in warm tropical aquariums.

Lighting

• Requirement: Moderate to High

• Note: Needs bright light to thrive underwater, but high light in a tank makes it prone to algae cover due to its slow growth.

CO2

• Requirement: Not Required.

Propagation

• Method: Spores or Crown Division

• How it works: Naturally reproduces by releasing microspores and megaspores from the leaf bases. In cultivation, mature plants with multiple crowns can be carefully split at the base and replanted in soft, sandy substrate.