Hydrocotyle sometimes called water pennywort

Pennywort

Pennywort is a name given to several completely different plants around the world. In general they all have round leaves and a low-growing habit...

, Indian Pennywort, Marsh Penny, Thick-leaved Pennywort and even White Rot
is a genus of prostrate, perennial aquatic or semi-aquatic plant

Aquatic plant

Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...

s formerly classified in the family Apiaceae

Apiaceae

The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...

, now in the family Araliaceae

Araliaceae

Araliaceae is a family of flowering plants, also known as the Aralia family or Ivy family. The family includes 254 species of trees, shrubs, lianas and perennial herbaceous plants into 2 subfamilies...

.

Description

Water pennyworts, Hydrocotyles are very common. They have long creeping stems that often form dense mats, often in and near ponds, lakes, rivers, marshes and some species in coastal areas by the sea.
Leaves: Simple, with small leafy outgrowth at the base, kidney shaped to round. Leaf edges are scalloped.
Flowers: Flower clusters are simple and flat-topped or rounded. Involucral bracts Inconspicuous bracts at the base of each flower. Indistinct sepals.
Fruits and reproduction: Elliptical to round with thin ridges and no oil tubes (Vitta

Vitta

Vitta may refer to:*Estádio Décio Vitta, a multi-use stadium*Hasora vitta, a butterfly*Mandello Vitta, a comune in the Province of Novara in the Italian region Piedmont*Vitta Foods...

) which is characteristic in the fruit of umbelliferous plants.

The prostrate plants reproduce by seed and by sending roots from stem nodes.

Selected species

The Hydrocotyle genus has between 75 and 100 species that grow in tropical and temperate

Temperate

In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...

 regions worldwide and a few species have made it into the world of cultivated ornamental aquatics. A list of selected species:

• Hydrocotyle americana L. -- American marshpennywort
• Hydrocotyle batrachium Hance
• Hydrocotyle benguetensis Elm.
• Hydrocotyle bonariensis
  Hydrocotyle bonariensis
  Hydrocotyle bonariensis once a member of the family Apiaceae, now in the family Araliaceae and of the genus Hydrocotyle is a hairless and creepy perennial.-Description:Flowers: Numerous white to creamy yellow flowers, flower stalks can be ....
  
  Lam. -- largeleaf pennywort
• Hydrocotyle bowlesioides Mathias & Constance—largeleaf marshpennywort
• Hydrocotyle calcicola
• Hydrocotyle dichondroides Makino
• Hydrocotyle dielsiana
• Hydrocotyle heteromeria -- waxweed
• Hydrocotyle hexagona
  Hydrocotyle hexagona
  Hydrocotyle hexagona is a species of flowering plant in the Apiaceae family.It is endemic to Ecuador.Its natural habitat is subtropical or tropical moist montanes.It is threatened by habitat loss.-References:...
  
  
• Hydrocotyle himalaica
• Hydrocotyle hirsuta Sw. -- yerba de clavo
• Hydrocotyle hitchcockii
  Hydrocotyle hitchcockii
  Hydrocotyle hitchcockii is a species of flowering plant in the Apiaceae family.It is endemic to Ecuador.Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montanes.It is threatened by habitat loss....
  
  
• Hydrocotyle hookeri
• Hydrocotyle javanica
  Hydrocotyle javanica
  Hydrocotyle javanica, commonly known as Pennywort, is a species of Hydrocotyle....
  
  Thunb.
• Hydrocotyle keelungensis Liu, Chao & Chuang
• Hydrocotyle leucocephala Cham. & Schltdl. -- Brazilian pennywort
• Hydrocotyle mannii Hook.f.
• Hydrocotyle microphylla A.Cunn.
• Hydrocotyle moschata G. Forst. -- musky marshpennywort
• Hydrocotyle nepalensis Hook.
• Hydrocotyle novae-zelandiae DC.
• Hydrocotyle prolifera Kellogg—whorled marshpennywort
• Hydrocotyle pseudoconferta
• Hydrocotyle pusilla A. Rich. -- tropical marshpennywort
• Hydrocotyle ramiflora
• Hydrocotyle ranunculoides
  Hydrocotyle ranunculoides
  Hydrocotyle ranunculoides, known commonly as water pennywort or floating pennywort is an aquatic plant in the Apiaceae. It is native to North and South America and parts of Africa. In the UK it is an invasive alien species which is currently spreading in waterways in the UK. It is also a weed in...
  
  L. f. -- floating marshpennywort, floating marshpennywort, floating pennyroyal
• Hydrocotyle salwinica
• Hydrocotyle setulosa Hayata
• Hydrocotyle sibthorpioides Lam. -- lawn marshpennywort
• Hydrocotyle tambalomaensis
  Hydrocotyle tambalomaensis
  Hydrocotyle tambalomaensis is a species of flowering plant in the Apiaceae family.It is endemic to Ecuador.Its natural habitats are subtropical or tropical moist montanes and subtropical or tropical high-altitude grassland....
  
  
• Hydrocotyle tripartita
• Hydrocotyle umbellata
  Hydrocotyle umbellata
  Hydrocotyle umbellata, is an aquatic plant that thrives in wet, sandy habitat. Its English common name is manyflower marsh pennywort or dollarweed. It is native to North America and parts of South America. It can also be found growing as an introduced species and sometimes a noxious weed on other...
  
  L. -- manyflower marshpennywort, umbrella pennyroyal
• Hydrocotyle verticillata
  Hydrocotyle verticillata
  Hydrocotyle verticillata, also known as Whorled Pennywort, and Shield Pennywort, is a flowering plant found in South and North America and the West Indies. The creeping plants with unusual leaves give it its common names. It grows in places that are marshy, boggy, and wet...
  
  Thunb. -- whorled marshpennywort, whorled marshpennywort, whorled pennyroyal
• Hydrocotyle vulgaris
  Hydrocotyle vulgaris
  Hydrocotyle vulgaris, also known as Marsh Pennywort, is a small creeping perennial herb native to N. Africa, Europe, Florida, and west to the Caspian region; in Britain it is the only native Hydrocotyle....
  
  L.
• Hydrocotyle wilfordii
• Hydrocotyle wilsonii
• Hydrocotyle yanghuangensis
  Hydrocotyle yanghuangensis
  Hydrocotyle yanghuangensis is a species of flowering plant in the Apiaceae family.It is endemic to Ecuador.Its natural habitats are subtropical or tropical moist montanes and subtropical or tropical high-altitude grassland....