''Pilea'', with 600–715 species, is the largest

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s in the nettle

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Urticaceae The Urticaceae are a family, the nettle family, of flowering plants. The family name comes from the genus ''Urtica''. The Urticaceae include a number of well-known and useful plants, including nettles in the genus ''Urtica'', ramie (''Boehmeri ...

. It is distributed throughout the tropics, subtropics, and warm temperate regions (with the exception of

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

Description

The majority of species are

succulent In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...

shade-loving

herbaceous plant Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of t ...

s or

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

s, which are easily distinguished from other Urticaceae by the combination of

opposite leaves In botany, phyllotaxis () or phyllotaxy is the arrangement of leaves on a plant stem. Phyllotactic spirals form a distinctive class of patterns in nature. Leaf arrangement The basic arrangements of leaves on a stem are opposite and alterna ...

(with rare exceptions) with a single ligulate intrapetiolar

stipule In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many speci ...

in each leaf axil and cymose or paniculate inflorescences (again with rare exceptions).

Uses

''Pilea'' is of little economic importance; one species is used in

Chinese traditional medicine Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of action ...

(''P. plataniflora'').

Horticulture

Six species have horticultural value (''P. cadierei'', ''P. grandifolia'', ''P. involucrata'', ''P. microphylla'', ''P. nummulariifolia'', and ''P. peperomioides''), Some pileas are grown for their ornamental

foliage A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, s ...

which is shaped like lily-pads. The ASPCA includes many peperomia species in the list of plants that are non-toxic to pets.

Systematics

The genus has attracted little monographic attention since Weddell (1869), and the majority of taxonomic contributions have come from floristic treatments. To date, 787 species names have been published (International Plant Names Index, 2003) and estimates for the species number range from 250 to 1000. Based on previous floristic treatments, about 30% of the species from regions not yet covered by contemporary floristic treatments may be undescribed. The genus name ''Pilea'' is

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

for "felt cap", a reference to the calyx covering the

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...

Selected species

*''

Pilea cadierei ''Pilea cadierei'', the aluminium plant or watermelon pilea, is a species of flowering plant in the nettle family Urticaceae, native to China (provinces of Guizhou and Yunnan) and Vietnam. The specific epithet ''cadierei'' refers to the 20th-cen ...

'' — aluminium plant *'' Pilea cataractae'' *''

Pilea cavernicola ''Pilea cavernicola'' is a herbaceous plant about 0.5 meters tall, native to China. A sciophyte, it grows in very low light conditions in caves in Fengshan County Fengshan County (, zhuang: Fonghsan Yen) is a county of Guangxi, China. It ...

'' *''

Pilea crassifolia ''Pilea crassifolia'' is a plant native to Central and South America. One well-known cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to ...

'' *''

Pilea depressa ''Pilea depressa'', the depressed clearweed, also sold as kiereweed, is a plant native to the Caribbean.Pilea de ...

'' *'' Pilea elegans'' *''

Pilea fontana ''Pilea fontana'', the lesser clearweed, is an herbaceous plant which is very similar to '' Pilea pumila'' (both occupying an almost identical range covering most of North America east of the Rocky Mountains The Rocky Mountains, also known a ...

'' *''

Pilea glaucophylla ''Pilea glaucophylla'', the silver-leaved artillery plant, is a species of flowering plant in the family Urticaceae The Urticaceae are a family, the nettle family, of flowering plants. The family name comes from the genus ''Urtica''. The Urt ...

'' *''

Pilea grandifolia ''Pilea grandifolia'' is an undershrub native only to Jamaica. It is sometimes cultivated.
''National B ...

'' *''

Pilea involucrata ''Pilea involucrata'', commonly called the friendship plant, is a bushy trailing plant which is sometimes cultivated, especially where high humidity can be provided, such as in a terrarium A terrarium (plural: terraria or terrariums) is usua ...

'' — friendship plant *'' Pilea jamesonia'' *''

Pilea laevicaulis ''Pilea laevicaulis'' is a species of plant in the family Urticaceae. It is endemic to Mauritius. Its natural habitat is subtropical or tropical dry forest A forest is an area of land dominated by trees. Hundreds of definitions of fores ...

'' *''

Pilea microphylla ''Pilea microphylla'' also known as angeloweed, artillery plant, joypowder plant or (in Latin America) ''brilhantina'' is an annual plant native to Florida, Mexico, the West Indies, and tropical Central America, Central and South America, Sout ...

'' — artillery plant, gunpowder plant *''

Pilea mollis ''Pilea mollis'' is a species of flowering plant in the family Urticaceae. It is used as an ornamental plant, particularly the cultivar 'Moon Valley'. References mollis Mollis is a former municipality in the canton of Glarus in Switzerl ...

'' — Moon Valley plant *'' Pilea myriophylla'' *'' Pilea napoana'' *'' Pilea nummulariifolia'' — creeping Charlie *''

Pilea peperomioides ''Pilea peperomioides'' (), the Chinese money plant, UFO plant, pancake plant or missionary plant, is a species of flowering plant in the nettle family Urticaceae, native to Yunnan and Sichuan provinces in southern China. History The Scottish ...

'' — Chinese money plant, missionary plant *'' Pilea pollicaris'' *''

Pilea pumila ''Pilea pumila'', commonly known as clearweed, Canadian clearweed, coolwort or richweed, is an herbaceous plant in the nettle family (Urticaceae). It is native to Asia and eastern North America, where it is broadly distributed. This plant is mos ...

'' — Canadian clearweed *'' Pilea repens'' — black-leaf panamiga *'' Pilea riopalenquensis'' *'' Pilea schimpfii'' *'' Pilea selbyanorum'' *'' Pilea serpyllacea'' *'' Pilea serratifolia'' *'' Pilea spruceana'' *'' Pilea topensis'' *'' Pilea trianthemoides'' *'' Pilea trichosanthes'' *'' Pilea trilobata'' *'' Pilea tungurahuae'' *'' Pilea victoriae''

Fossil record

The

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

species †''Pilea cantalensis'' was widely distributed in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

and

West Siberia Western Siberia or West Siberia (russian: Западная Сибирь, Zapadnaya Sibir'; kk, Батыс Сібір) is a part of the larger region of Siberia that is mostly located in the Russian Federation. It lies between the Ural region an ...

during the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

and

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58

''Pilea mongolica'' and to the

North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Ca ...

''.Łańcucka-Środoniowa M.: Macroscopic plant remains from the freshwater Miocene of the Nowy Sącz Basin (West Carpathians, Poland) zczątki makroskopowe roślin z miocenu słodkowodnego Kotliny Sądeckiej (Karpaty Zachodnie, Polska) Acta Palaeobotanica 1979 20 (1): 3-117.

References

* * *Hortus Third, pages 872-873 * * * *
USDA U.S. Dept. of Agriculture Plants Database

Description

Uses

Horticulture

Systematics

Selected species

Fossil record

References

Further reading