Author: Bryce Millar, MD
Common Names: Mint bacopa, lemon bacopa, blue waterhyssop
Order: Scrophulariales (Lamiales)
Family: Scrophulariaceae (Plantaginaceae)
Native Distribution: Southeastern United States, from Texas to Maryland
Aquarium Placement: Background
Requirements: Exceptionally undemanding
Bacopa caroliniana is one of the most popular and easily obtained plants in the aquarium hobby. Its reputation as an old standby is well-deserved, as it is quite undemanding. Its bold leaf structure and relatively slow-growth pattern make it a popular choice in aquascaping. It can be shaped at the discretion of the aquarist.
Coloration is generally greenish yellow, but under intense light or in the upper portions of the aquarium, growing shoots will often gain a pinkish or copper-brown color.
As with most plants, coloration is improved with regular iron and micronutrient dosing. CO2and macronutrient supplementation will result in slightly faster growth, and leaves will be markedly thicker and larger.
When cut or crushed, the plant produces a strong lemon-mint smell. B. caroliniana can also be kept in outdoor ponds or tubs. When allowed to grow in an emersed state, it will produce characteristic small purple flowers.
Uses in Aquascaping
Single large stems can be allowed to grow slowly upward. A group of such specimens will produce long, solid stalks with circumferential leaf groups. This technique can create a strong vertical element in an aquascape.
Alternatively, this plant can be regularly pruned. Once the growing tip is removed, the plant will respond in classic style with a proliferation of side shoots. After a few cycles of pruning, the resultant plant will reward the patient aquarist with a thick, bushy growth structure. After a few months the lower parts of the plant gradually degrade and diminish the plant’s appearance. This is easily remedied by uprooting the plant and removing the lower lanky portions.
B. caroliniana is easily cultivated. Removal of the central growth tip will produce numerous side shoots within a few weeks. These can be removed near their attachment to the primary stem and secured in the substrate, where they will rapidly take root.
Notes: Several other Bacopa species are also popular in the hobby. In general, these plants are similar to caroliniana when it comes to structure and hardiness. Most are undemanding. Some (such as Bacopasp. “colorata”) are more brilliantly colored, and others (such as Bacopa monnieri) have smaller individual leaf structures.