Description
tala rotundifolia (variants include Rotala Colorata, H'ra, Ceylon, etc) is a fast growing stem plant that has been a staple of the planted aquarium world for a long time. It was first introduced under the erroneous name of Rotala indica around the year 1960, a confusion lasting to this date. The description of real Rotala indica can be found here - along with the explanation of how the names got mixed up.
It is tolerant of a wide range of water parameters and is an easy plant to grow; it does well even in aquariums without carbon dioxide injection after a period of adjustment. However, having sufficient light and CO2 allows it to grow with better density, and better coloration.
As stem plants they grow continually towards the light and will reach the top of even tall aquariums. If allowed to reach the water surface it will breach the surface eventually and grow emersed leaves and flowers. If stems are planted in a tank with high light and with a lot of space surrounding them, they will grow downwards and creep along the substrate. If planted in a more crowded area they will grow vertical more readily.
The plant branches more profusely when in fast growth mode, and grows more vertical with less branching if conditions are lean (either low CO2 or low nutrients).