Alternanthera reineckii 'Pink': grower data and red color

What the grower data says

Tropica rates ‘Pink’ medium across the board: medium difficulty, medium light, medium CO2 and medium growth, with stems 20–30 cm or more after two months and 25–50 cm in its description ^[1]. Its fertilizer guide spells out what the “medium” category implies: plants marked medium need added CO2, roughly 10–15 mg/L ^[4]. So this is the point on the scale where CO2 injection stops being optional, according to the grower.

Aquasabi does not profile ‘Pink’ itself. Its profile of the smaller ‘Mini’ form matches the pattern: medium difficulty, medium light and CO2 required, with a care height of 5–20 cm ^[3]. Tropica also sells ‘Mini’ and a pink-veined ‘Rosanervig’ alongside ‘Pink’ ^[2].

Color

The selling point is the leaf color. Tropica describes the pink underside of the leaves as an effective contrast to the many green plants in an aquarium, particularly when planted in groups, and says that good light encourages the leaves to turn red ^[1]. Light is the lever the grower names; the light ratings guide explains what “medium” light means in Tropica’s own terms.

Among the red stem plants

Of the red stem plants profiled on this site, ‘Pink’ is the most demanding by Tropica’s ratings ^{[1, 5]}:

Plant	Difficulty	Light	CO2
Ludwigia palustris ‘Super Red’	Easy	Low	Low
Rotala rotundifolia	Easy	Low	Low
Alternanthera reineckii ‘Pink’	Medium	Medium	Medium

For the two easy plants, Rotala rotundifolia and ‘Super Red’, Tropica’s own descriptions tie the red color to good light (and for ‘Super Red’, added CO2), so a low rating does not promise red leaves at low light. See the Ludwigia ‘Super Red’ and Rotala rotundifolia profiles.

Planting and propagation

Tropica recommends planting it in groups for the color contrast ^[1]. Propagation is by nipping off the terminal bud and planting it in the substrate. That one cut does two jobs: the tip becomes a new plant, and the mother plant becomes bushier because it forms more side shoots ^[1].

Names and taxonomy

Alternanthera reineckii Briq. is an accepted species in the World Checklist of Vascular Plants, in the amaranth family Amaranthaceae, with Achyranthes reineckii (Briq.) Standl. as its one synonym ^[6]. WCVP gives its native range as south-central South America: north-east and north-west Argentina, Bolivia, much of Brazil, Paraguay and Uruguay ^{[6, 7]}, consistent with Tropica’s statement that ‘Pink’ originated in South America ^[1]. ‘Pink’ is a trade form name; the checklist does not list cultivars.