Katniss(Sagittaria sagittifolia) is an aquatic plant that grows around District 12. Katniss is found in the meadow, the woods, and other parts of District 12. It is also the plant that Katniss Everdeen was named after.
It grows tall, with green leaves like arrow heads and flowers with three white petals. Katniss is known by many names, including sagittaria, arrowhead, duck potato, swan potato, tule potato, and wapato (wapatoo). Many are found in North and South America, but some are also native to parts of Europe, Africa, and Asia.
In The Hunger Games trilogy
Katniss Everdeen was named by her father after this plant. When Katniss was almost twelve years old, and first began to hunt and gather in the woods, the two would go to the lake to shoot waterfowl and collect katniss roots. Katniss was one of the first foods she found there. It was also part of her last meal with Gale Hawthorne before leaving for the Capitol.
Katniss finds this plant again (while wading in a stream) after her father dies and remembers something her father said "As long as you can find yourself, you'll never starve.". She picks this plant and feeds her family off it, until she can find something better to feed them.
The katniss plant is also known as "arrowhead," so her name may be interpreted as a reference to her skills in archery. On the other hand, it is both ornamental and useful, parallel to Katniss' varying roles in the Capitol and her own district.