"Water trumpet" is the common name applied to about 50 to 60 unique flowering aquatic plant species of the genus Cryptocoryne. The name refers to the unique shape of the flowers found on the plants, which have a slender cylindrical flower called a spadix encased in a sheath called a spathe that resembles the bell of a trumpet. Most species are indigenous to tropical parts of Asia and New Guinea, where they can be found growing in slower moving rivers, streams, and in seasonal flood plains. Since the water trumpet is accustomed to growing in an aquatic environment, it is usually cultivated as a decorative aquarium plant.
Most species of water trumpet are small, leafy plants that can grow up to a height of about 12 inches (30 centimeters). It has tapered oval leaves that grow on long stems. These leaves can be bright green, greenish brown, or red in color, depending on the species and variety of the individual plant. The flowers are typically reddish purple in color, with a unique trumpet shape. Many species of water trumpet cultivated in aquariums are reluctant to flower, making plant reproduction difficult.
The water trumpet can grow either completely underwater or partially above the water's surface. Plants that are totally submerged reproduce asexually, using vegetative reproduction. A water trumpet that emerges above the surface uses normal sexual reproduction, relying on the pollination of its flowers. Many growers who specialize in cultivating water trumpets for aquariums choose to slowly reduce water levels in the plants' growing environment, forcing the plants to flower and reproduce sexually.
When grown in an aquarium, the water trumpet prefers low light levels, as too much light can cause algae to accumulate on the plant's leaves. The plant tends to have a slow rate of growth, with most species reaching their full growth potential in about a year's time. Moving or transplanting a water trumpet, for example into a new fish tank, can slow its rate of growth even more.
These plants are delicate and susceptible to algae growth. They also occasionally suffer from a condition called "crypt melt," in which the plants rapidly lose their leaves. The cause of this condition is unknown, although the general theory is that drastic and sudden alterations to the plant's growing environment are the most likely cause. Although the plants are popular for planting in aquariums, the potential grower must also be careful to avoid placing them in tanks with fish that will use the plants as food.