Azolla filiculoides from North America is a small (1-2 cm tall), floating fern housing blue-green algae in its leaves. These algae are capable of absorbing nitrogen from the air, which can then be used by the plant.
Azolla filiculoides is used as nitrogen fertiliser in rice paddies, and as animal feed. There are several related varieties on the market, with similar appearance.
A decorative plant for open aquariums.
Tissue culture plants are grown in-vitro (literally: in the glass) in a nutrient-rich synthetic growing medium, either liquid or gel, without the presence of any other lifeforms. This guarantees a pest and disease-free specimen, while also providing accuracy throughout the trade.
Tissue culture plants should be removed from the cup as soon as possible. All plants grow on some sort of synthetic growing medium, ranging anywhere from liquid to jelly to firm gel. This should be removed and rinsed off. Gently massage the roots between your fingers until the gel dissolves away. Most plants can be broken up into smaller pieces and spread out in your aquarium. Smaller pieces are easier to plant.