Micranthemum umbrosum is a beautiful plant from US with small round leaves. It is suitable for small or large aquariums with stems becoming 10-25 cm long and 1-2 cm wide. Relatively demanding in terms of light. CO2 addition will promote growth.
Once the plant starts growing, it grows fast, and the shoots need to be pinched out often (can be planted as cuttings in the soil). Most beautiful in groups of many stems.