Plant atlas

Geographical Origin and Habitat: Hottonia palustris (commonly known as the Water Violet) is an aquatic plant native to the temperate regions of Europe and Western Asia. It inhabits shallow, nutrient-rich still waters, ditches, ponds, marshes, and slow-moving streams. It is a cool-climate species, growing both submerged in shallow water and emerged on wet mud during summer drawdowns.

Taxonomy & Genetics: Belongs to the Primulaceae family and the Hottonia genus. It is one of the few aquatic representatives of this family. Genetically stable, it has evolved unique morphological adaptations for submerged life, such as finely dissected, comb-like leaves to optimize gas exchange and light absorption in aquatic environments.

Physical Structure: Develops fleshy, upright, and branching stems that reach 20 to 40 cm in height. The leaves are arranged in dense whorls along the stems and are deeply pinnate, divided into fine, comb-like segments. In spring, it produces tall flower stalks that emerge above the water surface, bearing whorls of lilac, pink, or white flowers.

Color & Texture: Leaf blades display a striking, fresh light-green to bright-green color, which provides a beautiful contrast against darker or broad-leaved aquatic plants. The texture of the submerged foliage is extremely soft, feathery, and delicate, requiring gentle handling during planting and maintenance to prevent damage.

Lighting & CO2: Requires moderate to high lighting levels to maintain its bushy, compact growth form. Without sufficient light, the lower portions of the stems will shed leaves and decay. Carbon dioxide (CO2) injection is not strictly mandatory, but low-to-moderate levels (10-20 mg/L) greatly improve stem density and overall vitality.

Nutrition & Substrate: As a stem plant with a relatively delicate root system, it absorbs nutrients through both its roots and the water column. It benefits from a fertile substrate or root tabs containing iron and micronutrients, combined with a regular, balanced liquid fertilizer program.

Water Chemistry: Temperature control is the most critical factor for this species. It thrives in cool water, preferably between 18 and 22°C, and will quickly deteriorate in warm tropical aquariums where temperatures consistently exceed 24-25°C. Prefers a pH of 6.0 to 7.2 and soft to moderately hard water.

Space Management & Placement: Its beautiful feathery texture makes it an ideal midground plant for creating transitions. Stems should be planted in small groups, leaving a few centimeters of space between individual stalks to ensure adequate light penetration to the base and prevent self-shading.

Pruning: Easily propagated by taking stem cuttings. Cut the top few inches of a healthy stem using sharp aquascaping scissors and push the cutting into the substrate, where it will root quickly. The parent plant will respond by developing multiple side branches, creating a bushier appearance.

Risks & Diseases: The main threat is stem rot caused by warm water or shading of the lower leaves. The finely divided foliage easily traps floating detritus and organic debris, which can lead to localized rot or algae growth. Ensure good mechanical filtration and moderate water flow to keep the leaves clean.