Cryptocoryne undulata

Water parameters

Light and nutrients

Substrate type: nutrient preferred. Propagation: runners.

Substrate compatibility

With fish

Origin and habitat

Native to central Sri Lanka, in streams and river margins of the island's wet and intermediate zones. Cryptocoryne undulata Wendt, family Araceae, has medium leaves 10–30 cm long with distinctly wavy (undulate) margins, green above and often red beneath, the colour shifting toward reddish-brown under stronger light and paler green in low light. The surface can look faintly hammered, adding depth. Its taxonomy is tangled with neighbours in the C. wendtii and C. beckettii group: it was once treated as a form of C. willisii, and POWO lists C. willisii and C. axelrodii as synonyms, so plants sold under one of these names often belong to another. It is a medium-sized crypt for the midground.

Care notes

Easy care, all but interchangeable with C. wendtii and C. beckettii. It grows in low to moderate light with no CO2, in soft to moderately hard water around pH 6 to 8, and feeds at the root, so a nutrient-rich substrate or root tabs help. The wavy margins catch light for subtle movement even in still water, and brighter light deepens the reddish-brown tones and the undulation. Growth is moderate once settled, spreading by runners that bud daughter plants a few centimetres away, so a group of three to five fills a midground patch over a few months. As with all crypts, expect melt after a move or a parameter swing, leaving the firm roots in place to push new leaves within a few weeks. The tough leaves shrug off all but dedicated herbivores. In shops it is routinely sold under generic crypt labels alongside C. wendtii, and for care and aquascaping the two are effectively the same. It is an ornamental rosette, not a crop, so it is unsuited to media-bed aquaponics or hydroponics.

Further reading

• How to cycle a fish tank
• Water chemistry for fishkeepers: pH, GH, KH, and what they mean