a crassulaceous Eurasian rock plant, Umbilicus rupestris (or Cotyledon umbilicus), with whitish-green tubular flowers and rounded leaves
2.
a marsh plant, Hydrocotyle vulgaris, of Europe and North Africa, having circular leaves and greenish-pink flowers: family Hydrocotylaceae
3.
a gentianaceous plant, Obolaria virginica, of E North America, with fleshy scalelike leaves and small white or purplish flowers
4.
any of various other plants with rounded penny-like leaves
pennywort in American English
(ˈpɛniˌwɜrt)
noun
any of various plants with small round leaves growing in crevices of rocks and walls or in marshy places, as any of a genus (Hydrocotyle) of perennial plants of the umbel family and a small North American plant (Obolaria virginica) of the gentian family