Ludwigia
Genus of stem plants with shades ranging from green to blood red. Among the most colourful in planted freshwater aquariums.
Detailed explanation
The most widespread species are L. repens (easy, reddish-green), L. palustris (easy, red with intense light), L. arcuata (thin, orange-red), L. pantanal (intense red, very demanding).
In low light the Ludwigia remain green. With intense light and abundant iron they develop red and orange pigments.
They are pruned by cutting the tops and replanting them. Rapid growth with CO2. Easy species (repens, palustris) also work in low-tech aquariums.