Alternanthera reineckii "Rosaefolia"

Geographical Origin and Habitat: Alternanthera reineckii 'Rosaefolia' (also spelled 'Roseafolia') is native to the floodplain areas, marshes, and riverbanks of tropical South America, with a strong presence in Brazil, Paraguay, and northern Argentina. In its natural habitat, it grows both emersed and submerged, colonizing wet, muddy soils that are periodically flooded by seasonal rains. In these areas, it receives significant direct sunlight and humid tropical warmth.

Taxonomy & Genetics: Taxonomically, it is classified within the Amaranthaceae family, genus Alternanthera. 'Rosaefolia' is one of the most famous and widespread cultivars in the aquarium hobby, selected for the distinct fuchsia and pinkish-red

Color & Texture: ation on the underside of its leaves. Genetically, it shares the resilience of the wild type but exhibits a strong capacity to accumulate anthocyanins, protective pigments that filter excess light radiation and give it its signature reddish tones.

Physical Structure: It features an erect stem structure that is vigorous and becomes slightly woody at the base over time. The leaves are opposite, decussate, and lanceolate-ovate with slightly wavy margins, measuring between 4 and 8 cm in length. The plant develops a dense system of adventitious roots both in the substrate and along the lower nodes of the submerged stem, optimizing nutrient uptake directly from the water column.

Color & Texture: Color is the true strength of this cultivar: while the upper side of the leaves ranges from dark olive green to bronze-red or golden brown, the underside shines with an extremely bright and saturated fuchsia-pink or purple. The leaf texture is silky yet robust, with well-defined main veins that stand out on the surface, creating a dynamic color contrast under aquarium lighting.

Lighting & CO2: It requires moderate to high lighting to maintain its red color and stimulate compact growth with short internodes. CO2 injection is highly recommended at levels of 15-25 mg/L; without CO2, growth slows down significantly, and the plant

Risks & Diseases: shedding its lower leaves.

Nutrition & Substrate: It prefers a fertile substrate rich in iron and clay, which supports root development.

Water Chemistry: Highly flexible temperature-wise, it tolerates temperatures from 4°C to 30°C, though it performs best between 22°C and 26°C. It adapts to acidic or neutral pH (5.0-7.0) and carbonate hardness from very low to medium (KH 0-14 dKH). It is important to keep water parameters stable to avoid stress.

Space Management & Placement: The ideal placement is in the midground or background of the aquarium, preferably in groups composed of individual stems planted 2-3 cm apart. This placement allows light to reach the lower parts of the plant, preventing premature leaf loss.

Pruning: Pruning is done by cutting the stem above a leaf node. The cut apical portion can be replanted directly into the substrate to start a new plant, while the pruned stem will respond by developing two or more lateral shoots, making the original bush much denser.

Risks & Diseases: If grown in sub-optimal conditions (poor light or lack of CO2), it tends to decline, losing leaves and becoming an easy target for green spot or hair algae. Its tender leaves can be damaged by herbivorous fish or large shrimp if they are not adequately fed.