Habitat: Swamps, floodplain woods, wet roadside ditches,marshes, sometimes in standing water.

Leaves: Alternate - those not in water simple, linear-lanceolate to lanceolate to ovate, toothed, smooth, up to 2 inches long; those submersed in water deeply pinnately divided, smooth.

Growth: medium
Demands: medium
Country of origin: Cuba
Height: 5-15 cm
Width: 5-8 cm
Light requirements: medium - very high
Temperature: 20-28 °C
Hardness tolerance: soft - hard
pH tolerance: 6 - 8

Mermaidweed goes though changes when grown submerged.

As you can see here, the growth of this plant changes when it's submerged.
It takes about three weeks to change.

I also find this plant hard to grow submerged for more then six months. If submerged longer, the plant will get leggy.

I have only grown this plant in one tank; a 55gal. CO2, 2.7w/gal. ferts 2/week, weekly water change. In this tank it grows slow but steady.
Here is a picture of Proserpinaca palustris (Marsh Mermaidweed) in the wild.

All in all I like this plant but when used in an aquascaping setting,
I believe the plant would have to be replace often to insure the best
appearance of the Marsh Mermaidwed.