Underwater Flowers?

Most commercial aquatic plants flower above water.

However, some like to flower underwater. Above are the buds and flowers of Barclaya longifolia (the red plant). In the background are the flower stems of Eriocaulon cinereum (the taller green stems with white tips).

The majority of commercially traded aquatic plants are species that can grow both above (emersed) and below (submerged) water. For most of these species, flowering usually only occurs above water when the plant senses access to air. Plants may send out flower stems that penetrate the water surface or, in the case of stem plants, grow tall enough to rise above the water surface before flowering occurs. Insects and wind are the main pollinators in nature.

Very few aquatic plants are pollinated by water (hydrophily); certain Ceratophyllum and Najas species are capable of this. In these plants, the pollen floats in the water to reach another plant.

However, some species flower regularly under water, such as Bucephalandra (see below).

These flowers are non-functional and deteriorate quickly underwater. However, for a few days they can look amazingly decorative.

But be careful

Plants that flower underwater can also be triggered by stress or other drastic changes in tank parameters (light, temperature, etc.). So the appearance of flowers is not always a sign of radiant health!

In the case of Eriocaulons, in some species, such as the E. cinereum above, the flower stalks signal the end of the plant's life cycle. In this scenario, the plant should have been split-propagated to induce baby spawning (see the Eriocaulon propagation page) before the flowering cycle. Removing the flower stems could delay the effect by forcing the plant to divert energy to leaf growth rather than flower growth.

Flowering eriocaulon

Above: The taller green shoots with whitish balls at their ends are the flower stalks of Eriocaulon quinquangulare. This species occasionally flowers underwater.

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