Cryptocoryne thwaitesii grows in the stable watershed that springs out from the deep forest.
The natural growth method is very special and it is not growing in the whole stream, but it seems that a small number of plants are growing only in a very narrow range of meters below the forest in clearings. Even plants in Sri Lanka are particularly threatened with extinction. It is very easy for plant collectors and others to take everything from a location in a short period of time because the number of locations itself is small.
Cryptocoryne thwaitesii is a prostate growing plant with wide ovate leaves. It is found in Sri Lanka but its natural habitat is slowly and steadily disappearing. Purchasing wild collected stock should be avoided, instead propagate it yourself.
Propagation of Crypocoryne thwaitesii can be done much easier and much faster emersed. An acidic substrate made with one part peat and one part coarse sand or fine gravel grows them sufficiently. Slow release fertilizer like Osmocote spread lightly throughout the substrate will help the roots find nutrients for growth. Do not bury the rhizome too deeply in the substrate and don’t keep the water level much higher than the crown on the rhizome. Plastic totes or bins with a clear lid will hold enough humidity.
Emersed growth increases leaf thickness and helps to prevent evaporation of moisture (transpiration) by changing the surface of the leaves. In addition, to adapt to the very dark environment where the growing place is, the back of the leaf is made red and it is shaped so that light can be taken in efficiently. These physical changes in leave composition is why cryptocoryne tend to ‘melt’ when moved or changed from submerged to emergent or vice versa.
by Yosuke Kobayashi
Images by Yosuke Kobayashi