Question: Which is an aquatic plant, Pontederia or Heuchera?
Context: Nelumbo nucifera, also known as Indian lotus, sacred lotus, bean of India, Egyptian bean or simply lotus, is one of two extant species of aquatic plant in the family Nelumbonaceae.  The Linnaean binomial "Nelumbo nucifera" (Gaertn. ) is the currently recognized name for this species, which has been classified under the former names, "Nelumbium speciosum" (Willd. ) and "Nymphaea nelumbo", among others.  (These names are obsolete synonyms and should be avoided in current works.)  This plant is an aquatic perennial.  Under favorable circumstances its seeds may remain viable for many years, with the oldest recorded lotus germination being from that of seeds 1,300 years old recovered from a dry lakebed in northeastern China. Heuchera is a genus of evergreen, herbaceous perennial plants in the family Saxifragaceae, all native to North America.  Common names include alumroot and coral bells. Pogostemon stellatus is an aquatic perennial herb from eastern and southeastern Asia, the Indian Subcontinent, New Guinea, and northern Australia.  Because of its extensive geographic distribution, there are many different color and leaf forms of this plant in the wild.  It is a highly prized and sought after aquatic plant in the aquarium trade. An aquatic weed harvester, also known as a water mower, mowing boat and weed cutting boat, is an aquatic machine specifically designed for inland watercourse management to cut and harvest underwater weeds, reeds and other aquatic plant life.  The action of removing aquatic plant life in such a manner has been referred to as "aquatic harvesting". Pontederia is a genus of tristylous aquatic plants, members of which are commonly known as pickerel weeds.  "Pontederia" is endemic to the Americas, distributed from Canada to Argentina, where it is found in shallow water or on mud.  The genus was named by Linnaeus in honour of the Italian botanist Giulio Pontedera. Wolffia arrhiza is a species of flowering plant known by the common names spotless watermeal and rootless duckweed, belonging to the Araceae, a family rich in water-loving species, such as "Arum" and "Pistia".  It is the smallest vascular plant on Earth.  It is native to Europe, Africa, and parts of Asia, and it is present in other parts of the world as a naturalized species.  It is an aquatic plant which grows in quiet water bodies such as ponds.  The green part of the plant, the frond, is a sphere measuring about 1 mm wide, but with a flat top that floats at the water's surface.  It has a few parallel rows of stomata.  There is no root.  The plant produces a minute flower fully equipped with one stamen and one pistil.  It often multiplies by vegetative reproduction, however, with the rounded part budding off into a new individual.  In cooler conditions the plant becomes dormant and sinks to the bed of the water body to overwinter as a turion.  The plant is a mixotroph which can produce its own energy by photosynthesis or absorb it from the environment in the form of dissolved carbon. A macrophyte is an aquatic plant that grows in or near water and is either emergent, submergent, or floating, and includes helophytes (a plant that grows in marsh, partly submerged in water, so that it regrows from buds below the water surface).  In lakes and rivers macrophytes provide cover for fish and substrate for aquatic invertebrates, produce oxygen, and act as food for some fish and wildlife. Echinodorus grisebachii or Echinodorus amazonicus is commonly known as Amazon sword plant, although other plants are also known under this common name.  The aquatic plant is cultivated for and used in ponds and artificial aquatic habitats.  It is native to Cuba, Central America, and South America as far south as Brazil and Bolivia. Pontederia cordata, common name pickerelweed (USA) or pickerel weed (UK), is a monocotyledonous aquatic plant native to the American continent.  It grows in a variety of wetlands, including pond and lake margins across an extremely large range from eastern Canada south to Argentina.  A few examples include northern rivers, the Everglades and Louisiana. Thalia dealbata, the powdery alligator-flag, hardy canna, or powdery thalia, is an aquatic plant in the family Marantaceae, native to swamps, ponds and other wetlands in the southern and central United States.  Its range includes much of Coastal Plains and the lower Mississippi Valley (States of South Carolina, Georgia, Alabama, Mississippi, Louisiana, Texas, Oklahoma, Arkansas, Missouri, Illinois and Kentucky).  The plant has been grown as an aquatic ornamental because of the pretty violet flowers, and in cultivation has been proved hardy as far north as Philadelphia (Pennsylvania) and Vancouver (British Columbia).
Answer: Pontederia