Alternanthera reineckii

Also known as AR, Scarlet temple, Telanthera reineckii, Water hedge, Alternanthera reineckii 'Rosaefolia'

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Alternanthera reineckii (Alternanthera reineckii) — Drhyperlaur (talk) (Uploads) · Public domain

Care at a glance

Light: High light
CO2: CO₂ beneficial
Growth rate: Medium
Placement: Midground
Type: Stem
Temperature: 72–82°F (22–28°C)
pH: 6.0–7.5
Hardness: 3–12 dGH
Max height: 19.7 in (50 cm)
Spread: 5.9 in (15 cm)
Nutrient uptake: Root + water column
Growth region: Submersed or emersed
Difficulty: Medium
Origin: South America (Brazil, Paraguay, Argentina, Bolivia, Uruguay)
Family: Amaranthaceae

Overview

One of the most popular red plants and among the more forgiving, but it still wants high light, good water-column dosing including iron, and CO2 to hold dense red color and avoid losing lower leaves. Plant single stems spaced apart in the mid-ground so light reaches the whole stem; replant trimmed tops to bush it out. It grows at a moderate pace rather than fast. Without CO2 it can survive and even color up reasonably, but growth slows and it becomes more algae-prone, so adjust expectations in a low-tech tank.

In the wild

Native to South America, ranging across southern Brazil, Paraguay, northern Argentina, Bolivia, and Uruguay. It grows in marshes, stream banks, and seasonally flooded ground, living both submersed and as a semi-aquatic marsh plant. The leaves are green to olive on top and pink to deep red underneath, with several cultivars selected for stronger color.

Good to know

A member of the amaranth family (Amaranthaceae), historically traded under the genus name Telanthera. The red coloration comes from anthocyanin and carotenoid pigments concentrated on the leaf undersides, and the plant's color response is strongly tied to iron and overall nutrient availability. Numerous trade cultivars ('Rosanervig', 'Pink', 'Mini', 'Variegated') are all forms of this one species.

Did you know

Iron, not just light, drives its color: starve Alternanthera reineckii of iron and the leaves fade to pale pink or green no matter how bright the lighting, which is why dedicated iron dosing is a standard trick for keeping it red.