Cryptocoryne crispatula var. 'tonkinensis' is a variety of the highly variable Crytocoryne crispatula species that was first discovered in Thailand and since confirmed to range throughout Southeast Asia in to China. Its leaves are slender, perhaps an adaptation to it's flowing river habitats, compared to the more common 'Balansae' variety.

Submerged leaves are long, lanceolate, almost linear with a “whole” undulate margin and "crispate" texture. Coloration is dependent on environmental conditions with a range of green being most common though high lighting intensity can produce reddish brown leaves. This plant can put out of a lot of leaves so it will take on a substantial role in your aquascape that is hard to ignore. Luckily, it's quite stately looking so you'll be glad that it's there.

Because of its natural riverine habitat, 'Tonkinensis' leaves are very flexible and ribbon-like. In an aquarium with good water movement, they will sway soothingly in the current.

This is one of the few plants that can make do with a weak light source - it will not wither away even in the dimmest conditions making it an ideal beginner plant or a plant for a simple fish bowl. Provided with more light it will grow much faster and more voluminous. C. cripatula may able to use bicarbonate or other forms of non-gaseous carbon so CO2 injection is unnecessary though it will definitely supercharge growth rate.

Unlike a majority of aquarium plants, but unsurprising for Cryptocorynes, C. crispatula tolerates and in fact prefers harder water with alkaline pH. This plant can tolerate water so hard, that in the wild, it has been found with visible lime scaling on its leaves. For that reason, it is one of the few plants that can be grown in dimly lit, hardwater, African Rift cichlid aquariums provided it's well rooted.