Ludwigia polycarpa - Globefruit Primrose-willow

Ludwigia polycarpa, the Many-fruited water-primrose, is pretty new to the aquarium hobby. This species originates from North America as well as the similar Ludwigia sphaerocarpa. It occurs from the eastern and central USA to southeastern Canada in floodplains, river and lake shores and swamps. Its terrestrial form looks rather inconspicuous, with narrow, green leaves and small, greenish flowers on long stems.

The more attractive are its compact, almost rosette-like submerged shoots. Grown under aquarium conditions, they reach a diameter of about 7-9 cm, are densely set with lanceolate, acute leaves and develop side branches at the base. Depending on the light intensity, the leaves show light green to light orange-brown tones.

Our experience to date has shown that the Many-fruited water-primrose grows a little faster in aquariums than Ludwigia sphaerocarpa and develops more sideshoots. Seemingly it is not too demanding, however we recommend rather strong lighting, CO2 addition and good nutrient supply, also via the substrate. It is propagated by cuttings of the main shoot and side branches.

As this Ludwigia species originates from the temperate zone of North America with cold winters, it is probably well suited for cold water tanks. However it also grows well at normal indoor temperatures above 20 °C. We don't yet know its tolerance of high temperatures above 26 °C.

In our opinion, Ludwigia polycarpa is an interesting addition to the aquarium flora. It looks decorative as a low bush in the midground.