Hygrophila costata

This plant originates from South America and stems become 25-60 cm long with 10 cm long leaves. Under water Hygrophila costata has relatively narrow leaves which are grouped close together. Plants sold in the shops are normally cultivated above water, and have rounder leaves with larger gaps between them.
Hygrophila costata was called Hygrophila corymbosa 'Angustifolia' until recently.