Hemianthus (Micranthemum) micranthemoides
Author: Bryce Millar, MD
Common Names: N/A
Native Distribution: Mid-Atlantic region of the United States
Aquarium Placement: Foreground or midground
Requirements: Undemanding, and adaptable to a variety of environments
Hemianthus micranthemoides is a well-known species that is popular in the hobby. This plant might actually be extinct in its native range and is listed by many state governments as either extirpated or endangered. There are some reports that the plant has not been seen in its native habitat since 1941. Fortunately, the species is widely available from commercial sources and is generally easy to keep in an aquarium setting.
H. micranthemoides is sometimes confused with other small-leaved species such as Micranthemum umbrosum and H. callitrichoides. All three species are frequently sold under the common name of “baby tears,” which only adds to the confusion. H. micranthemoides is perhaps the most undemanding of the three baby tears plants and is a great addition to almost any aquascape.
Modest light levels are all that is needed to maintain this plant. As with many species of stem plants, lower light levels will result in loose, upward growth, while bright illumination will result in more compact, shorter specimens. Both appearances can be attractive, depending on what look you are trying to achieve in your aquascape. Using CO2 supplementation and bright light will often result in exceptionally dense growth and pearling, as seen in the accompanying photograph. (Pearling is the production of visible streams of bubbles of oxygen that rise from plants during maximum photosynthesis.)
When the plants are kept under such ideal conditions, the addition of fertilizers, such as nitrate and phosphate supplementation, is needed to keep up with the plants’ production. Appropriate micronutrient supplementation also helps maintain a healthy, robust appearance. In aquaria without CO2 supplementation, growth is less dense, and the plant can probably obtain all of its needs from any of the commonly available plant substrates and other nutrients produced by the fish.
Growth can be rampant, but managing this plant is a simple matter. Heavy trimming is well tolerated and even recommended to promote dense growth. This also prevents lower portions of the plant from becoming shaded. Several cycles of trimming and growth will eventually produce the most appealing form. The grouping can then be left to grow wild and untidy, or it can be sculpted topiary-style into a desired shape.
Use in Aquascaping
Even for a stem plant, this species is extremely versatile. Trimmed short, it makes a nice foreground plant in medium or large aquaria and it can even be carefully cultivated in order to form a carpet on the ground of the aquarium. When left a little larger, visually impressive bushes can be formed in the midground. The small leaf size is also well suited for nano aquariums, where it can be pruned for use in the fore-, mid-, or background.
The plant will easily flower in the emersed state, but as with most all stem plants, vegetative propagation is easiest. Simply snip off pieces of the stems and group several together, burying them partially in the substrate. The original plants will respond with bushier growth, and the new plants will rapidly take root, soon developing new growth as long as the conditions are correct for the plant.