Lobelia cardinalis

Lobelia cardinalis is a North American wildflower that has been widely adopted in the planted aquarium hobby in its compact aquatic form. The round, spoon-shaped leaves are bright apple-green on the upper surface and a striking violet-purple on the underside — a contrast that becomes especially dramatic when light passes through the leaves from above. It grows at a slow to moderate pace and stays compact at 10–20 cm, suiting tanks from 40 litres upward. It is grown as a rosette-like stem plant, and trimming the top encourages bushy side branching over time.