Plant atlas

Geographical Origin and Habitat: While the name 'Sao Paulo' suggests a Brazilian origin, this specific form is likely a cultivar or a distinct variant discovered or popularized in the region. Many *Polygonum* (often now classified as *Persicaria*) species are wetland plants, thriving in tropical and subtropical habitats, typically along riverbanks, swamps, or seasonally inundated floodplains. Its adaptability to fluctuating conditions contributes to its robustness in an aquarium environment, where it benefits from nutrient-rich substrates and consistent moisture.

Taxonomy & Genetics: Botanically, *Polygonum* is a large and complex genus within the Polygonaceae family, though many aquatic species previously assigned to *Polygonum* have been reclassified into *Persicaria*. The designation 'sp. 'Sao Paulo'' indicates a specific, yet formally undescribed, species or a unique geographical variant, likely originating from or popularized in the vicinity of São Paulo, Brazil. This nomenclature highlights its distinct horticultural characteristics despite its uncertain exact species identity within the broader genus.

Physical Structure: Polygonum sp. 'Sao Paulo' is a classic stem plant, characterized by its upright growth habit and relatively robust stems. Its leaves are typically arranged alternately along the stem, featuring an ovate to lanceolate shape with smooth to slightly undulated margins. Under optimal conditions, the internodal spacing remains compact, contributing to a dense and bushy appearance, especially when regularly pruned.

Color & Texture: The most striking feature of Polygonum sp. 'Sao Paulo' is its vibrant coloration, which ranges from intense reddish-pink to deep purple or even coppery tones, particularly on the upper leaf surfaces and new growth. The undersides of the leaves often display a more muted pink or green hue, providing a subtle contrast. The leaf texture is generally smooth and somewhat delicate, yet the plant as a whole feels sturdy.

Lighting & CO2: This plant thrives under medium light conditions, where it will display its best coloration and maintain a vigorous growth rate. While it can tolerate lower light, intense red hues may diminish, and growth could become leggy. Supplemental CO2 injection is highly recommended to support its medium growth rate, optimize photosynthesis, and enhance nutrient uptake, leading to more robust health and richer color development.

Nutrition & Substrate: As a stem plant, Polygonum sp. 'Sao Paulo' absorbs nutrients primarily through its leaves from the

Water Chemistry: Maintaining stable water parameters within its preferred ranges is vital for the health of Polygonum sp. 'Sao Paulo'. It thrives in temperatures between 20-28°C, with a slightly acidic to neutral pH of 6.0-7.5, and a moderate carbonate hardness (KH) of 2-12. Consistent water changes are beneficial for replenishing essential minerals and preventing the accumulation of nitrates, contributing to a pristine environment.

Space Management & Placement: Positioned ideally in the midground of an aquascape, Polygonum sp. 'Sao Paulo' can create a captivating focal point or a vibrant transition zone between foreground and background plants. Its medium growth habit and potential for striking coloration make it an excellent choice for adding depth and visual interest. Planting in groups of several stems rather than individually enhances its impact and creates a more natural, lush appearance.

Pruning: Regular pruning is essential to maintain the desired shape, density, and health of Polygonum sp. 'Sao Paulo'. Trimming the upper sections of the stems encourages lateral branching, leading to a bushier growth habit and preventing the lower leaves from being shaded out. The trimmed tops can be replanted into the substrate to propagate new plants, ensuring a continuous supply of healthy specimens.

Risks & Diseases: Like many aquatic plants, Polygonum sp. 'Sao Paulo' can be susceptible to issues arising from unstable parameters, nutrient imbalances, or inadequate lighting. Common problems include stunted growth, chlorosis (yellowing leaves) due to iron deficiency, or melting during initial acclimation. Algae can also become an issue if lighting, CO2, and nutrient levels are not balanced, often adhering to the leaves.