Cryptocoryne affinis Hook. f. is distributed on the Malayan Peninsula (western Malaysia). It forms dense, mainly submersed populations on sand- and gravelbanks in rapidly flowing rivers and rivulets. Some of them lie in limestone areas.
This species was so widely spread in the hobby in earlier times that it was considered to be "the" Cryptocoryne. Around 1939 it was first mentioned as aquarium plant, and in the 1950s it was very popular under the name Cryptocoryne haerteliana (Haertel's water trumpet). Today, however, C. affinis is only found in low numbers even though new collections were made in its native habitat. This is probably due to the fact that similarly-looking species like C. wendtii and C. beckettii are far easier to propagate emersed in aquatic plant nurseries. Recently it became known that some other species (maybe C. wendtii?) are sold under the incorrect name Cryptocoryne affinis. True C. affinis is better available from other hobbyists, not from trade.
C. affinis is a very variable plant, there are forms that differ in height or leaf colour, and those with smooth to strongly bullous leaves, however, these characteristics can change a lot with the conditions the plant is kept in. One of the more frequently cultivated, smaller forms, e.g., has lanceolate leaves whose upper side is "silky" and dark green, with lighter-coloured yellowish-green longitudinal veins. Other forms have a clear brown leaf pattern. The underside can be light green to wine red.
Its final size also depends a lot on the conditions the plant is kept in: under stronger light and when planted at a distance the leaves lie relatively flat, and the plants form a rather low-lying carpet of only 10 cm in height. Dense groups under low light can grow to a height of around 40 cm, though. The leaves of emersed plants mainly lie spreaded on the ground.
The species C. affinis is best identified by its striking inflorescence, which seems to develop only infrequently in cultivation, unfortunately. The blade of the spathe is 3 to 20 cm long, its inside is of a dark purple, and it forms narrow spirals of 4 to 15 turns.
This crypt is an ideal plant for low-tech tanks with low light and no CO2 injection. It does well in hard water. After some time it forms subterranean runners, which help it to form dense, vast populations. Though C. affinis may be rather undemanding, it is quite susceptible to "crypt melt". This phenomenon often occurs if conditions like lighting or nutrient ratios change too quickly.
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