Hemianthus callitrichoides ”Cuba” – a beautiful carpet in AquaCube and in the aquarium

Found on: www.tropica.com

By Troels Andersen

This species of Hemianthus quickly forms a low, dense and brightly green carpet covering the bottom of the aquarium. Oxygen bubbles form on leaves resulting in vivid reflections of the light and in this way, a perfect foreground decoration is formed. Hemianthus callitrichoides may be planted directly into the substrate or attached to pieces of rocks and driftwood and it is suitable for large as well as small aquaria.

Photo by Oliver Knott

Hemianthus callitrichoides (048B) was recovered by Tropica’s founder Holger Windeløv during the dry season in a rocky river not far from Las Pozas about 90 km east of Havana in Cuba. Here, it was rooted in gravel between large rocks about 50 cm above the current water level of the river. The plant appeared as a dense pad shaped population very resistant to the heavy drag forces of the water which would have flooded and submerged the group of plants to about 1 meter depth during the rainy season. According to our information, Hemianthus callitrichoides is only found in Cuba, whereas Hemianthus micranthemoides (048A) is also found elsewhere in North America. Hemianthus callitrichoides belongs to the family of Scrophulariaceae and is thus closely related to Callitriche which has a more northern distribution.

Hemianthus callitrichoides forms low pads (3-6 cm) and thus, it is quite different from Hemianthus micranthemoides by having much shorter internodes but also smaller leaves. Hemianthus callitrichoides forms a unique flower which makes it easy to identify. With only 4 petals (versus 5) and only one central chamber in the fruit (versus 2) Hemianthus callitrichoides is easy to distinguish from Hemianthus micranthemoides. In addition, the leaves of Hemianthus callitrichoides are darker than those of Hemianthus micranthemoides.

Tropica grows Hemianthus callitrichoides in emergent cultures in stone wool and on coir fiber discs for the AquaCube. Hemianthus callitrichoides should be planted in large adjoining groups in the foreground of the aquarium. One pot grown in stone wool is easily divided into 7-8 portions which are then planted with a distance of a few cm. Within 3-4 weeks the plants will cover the bottom forming a beautiful green carpet. Likewise, Hemianthus callitrichoides is very suitable for the AquaCube where the oxygen bubbles contribute to the ornamental effect.

Hemianthus callitrichoides is not particularly light demanding, but the more light we provide, the more compact the growth form. Under limited light, the plant grows a bit longer (up to 20 cm). Hemianthus callitrichoides is fast growing and thus, it requires fertilizer (typically after 3-4 weeks) unless you have many fish in the aquarium. Iron deficiency is common and is recognized by the new leaves being yellowish. However, the deficiency is easily treated by using PLANT NUTRITION liquid in the recommended doses. At intense growth pruning may be necessary and it may be done like pruning grass. Like in most other cases, extra vivid growth is obtained by adding CO₂ but the beautiful oxygen bubbles are often formed also without using CO₂ enrichment. Hemianthus callitrichoides has its optimum temperature around 25 ºC but it thrives well from 20 to 28 ºC.

Hemianthus callitrichoides is perhaps one of the best and easiest foreground plants we have because it quickly forms a low carpet and the ornamental effect is highly improved by the oxygen bubbles which easily form on the leaves. However, many faster growing plants may overgrow Hemianthus callitrichoides and thus, it is necessary to prune neighboring plants every now and then.

Hemianthus callitrichoides is relatively new in our hobby and thus, the information about it is scarce. Hemianthus callitrichoides is botanically described in a Spanish flora (Flora de Cuba) and a few experiences from the aquarium are listed in the literature below.

Literature:
Kramer H G (2003) Hemianthus callitrichoides (flora aquatica). Aquaristik Fachmagazin 169: 74, in German