Wabi-kusa
Japanese plant composition: a ball of substrate with aquatic plants grown in emerged form. It is placed in a glass container with a little water.
Detailed explanation
Wabi-kusa is a Japanese botanical art invented by Takashi Amano and marketed by ADA. The name literally means "beauty in simplicity".
It is a sphere or hemisphere of substrate (the wabi-kusa ball) on which aquatic plants are planted in emerged form. The composition is placed in a low glass container (a bowl, a vase) with a few centimetres of water.
Aquatic plants grow surprisingly well in emerged form. Many species used in aquariums (Hemianthus, Rotala, Ludwigia, Glossostigma) are actually marsh plants that in nature grow out of water for a good part of the year.
The preparation of the substrate involves a peat core and nutrient substrate wrapped in moss (Sphagnum or aquatic moss). The plants are inserted into the moss with tweezers.
Maintenance is minimal: daily misting, topping up the water when it evaporates, indirect light or grow lamp. No filters, CO2 or liquid fertilisers are needed (the substrate provides everything).
Wabi-kusa is an elegant way to have a corner of nature on a windowsill, desk or table. It does not host fish (the water volume is too small) but can host small snails or dwarf shrimp in larger compositions.
In Japan there are competitions dedicated to wabi-kusa. The most successful compositions are small self-sustaining ecosystems that evolve over time.