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

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s in the nettle

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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 (''Boehmeria ...

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

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

Description

The majority of species are 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 o ...

s or

shrub A shrub or 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 by their multiple ...

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

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

(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 (botany), petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part ...

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 (''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 a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, f ...

which is shaped like lily-pads. The ASPCA includes many pilea 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 languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

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 fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

Selected species

*''

Pilea cadierei ''Pilea cadierei'' (or the aluminium plant or watermelon pilea) is a species of flowering plant in the nettle family Urticaceae. The species is endemic to the southern Chinese provinces of Guizhou and Yunnan, as well as Vietnam. The specific ep ...

'' — 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, Guangxi, China China, officially the People's Republic of China (PRC), ...

'' *''

Pilea crassifolia ''Pilea crassifolia'' is a plant native to Central and South America. One well-known cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those trait ...

'' *''

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

'' *''

Pilea elegans ''Pilea elegans'' 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 Urticaceae include a number of well-known an ...

'' *''

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). They can be distinguished by the ap ...

'' *''

Pilea glaucophylla ''Pilea glaucophylla'', the silver-leaved artillery plant, is a species of flowering plant in the family Urticaceae, native to Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with I ...

'' *''

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

'' *''

Pilea involucrata ''Pilea involucrata'' (Sims) Urb., commonly known as the friendship plant, is a species of flowering plant in the nettle family Urticaceae, native to Central and South America. It is a popular houseplant due to its unique foliage and relatively ...

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

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 A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic tr ...

'' — Moon Valley plant *'' Pilea myriophylla'' *'' Pilea napoana'' *'' Pilea nummulariifolia'' — creeping Charlie *'' Pilea peperomioides'' — Chinese money plant, missionary plant *'' Pilea pollicaris'' *'' Pilea pumila'' — 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 preserve ...

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

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and West Siberia during the

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

and

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58

''Pilea mongolica'' and to the

North American North America is a continent in the Northern and Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Caribbean Sea, and to the sou ...

'' Pilea pumila''.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