Clethra


Clethra is a genus of flowering shrubs or small trees described as a genus by Linnaeus in 1753.
Clethra is one of two genera in the family Clethraceae. The species may be evergreen or deciduous, and all bear flowers in clusters, which correspond to racemes or panicles. The flowers are quite small, white or pinkish, and each bear five free petals, numerous stamens, and a three-chambered seed capsule. The leaves, simple, ovate, and alternate or opposite, bear characteristic stellate hairs. The seeds are very small and numerous.

Distribution

Clethra species are native to a variety of habitats, including swamps, woodland, and rocky sites from temperate to tropical climates in eastern and southeastern Asia, Malesia, North and South America, and one species on the island of Madeira.

Fossil record

Several fossil fruits and seeds of †Clethra cimbrica have been described from middle Miocene strata of the Fasterholt area near Silkeborg in Central Jutland, Denmark.

Species

The number of species accepted varies between different authorities depending on taxonomic interpretation, but with a recent trend to reduce the number recognised as distinct. The recent Flora of China (series) has cut the number accepted for China from 35 to seven species, and the US Department of Agriculture recognises only two in the United States, synonymising C. tomentosa with C. alnifolia. The following are accepted by the World Checklist of Selected Plant Families:Clethra acuminata – mountain pepper bush; S Appalachians Clethra alcoceri – Hidalgo, JaliscoClethra alexandri – JamaicaClethra alnifolia – sweet pepper bush or summer sweet; S + E United States Clethra arborea – lily of the valley tree; Madeira, Canary Islands†, AzoresClethra arfakana – New GuineaClethra barbinervis – Japanese sweet shrub; SE China, Korea, JapanClethra bodinieri – S ChinaClethra canescens – Philippines, E + C Indonesia, New Guinea
  • * var. clementis – BorneoClethra castaneifolia – PeruClethra chiapensis – ChiapasClethra consimilis – Panama, Costa RicaClethra conzattiana – OaxacaClethra crispa – EcuadorClethra cubensis – CubaClethra cuneata – Peru, BoliviaClethra delavayi – SW China, Assam, Myanmar, Bhutan, VietnamClethra elongata – Peru, BoliviaClethra fabri – S China, VietnamClethra fagifolia – Ecuador, Colombia, VenezuelaClethra fargesii – C ChinaClethra ferruginea – PeruClethra fimbriata – Peru, Ecuador, ColombiaClethra formosa – Costa RicaClethra fragrans – Jalisco, Michoacán, GuerreroClethra galeottiana – Puebla, Oaxaca, ChiapasClethra gelida – Costa Rica, Panama, HondurasClethra guyanensis – Guyana, VenezuelaClethra hartwegii – C + S MexicoClethra hendersonii – Peninsular MalaysiaClethra hirsutovillosa – GuerreroClethra hondurensis – Tabasco to Costa RicaClethra javanica – Java, Bali, Lombok, TimorClethra kaipoensis – SE ChinaClethra kebarensis – New GuineaClethra licanioides – Guatemala, HondurasClethra longispicata – Borneo, Philippines, Sulawesi, MalukuClethra luzmariae – OaxacaClethra macrophylla – Veracruz, PueblaClethra mexicana – C + S Mexico, Central America, Colombia, Venezuela, TrinidadClethra oaxacana – OaxacaClethra obovata – Ecuador, PeruClethra occidentalis – JamaicaClethra oleoides – C + S Mexico, Central AmericaClethra ovalifolia – Colombia, Venezuela, Ecuador, PeruClethra pachecoana – Chiapas to HondurasClethra pachyphylla – BorneoClethra papuana – New GuineaClethra paralelinervia – EcuadorClethra × parvifolia – ChiapasClethra pedicellaris – Colombia, Ecuador, PeruClethra peruviana – Ecuador, PeruClethra petelotii – Vietnam, YunnanClethra poilanei – LaosClethra pringlei – Mexican summersweet – MexicoClethra pulgarensis – PalawanClethra purpusii – Oaxaca, ChiapasClethra pyrogena – Panama, Costa RicaClethra repanda – Colombia, VenezuelaClethra retivenia – PeruClethra revoluta – Colombia, Bolivia, Ecuador, PeruClethra rosei – MexicoClethra rugosa – Colombia, EcuadorClethra scabra – Brazil, Bolivia, Paraguay, NW ArgentinaClethra skutchii – GuatemalaClethra sleumeriana – HunanClethra suaveolens – S Mexico, Central AmericaClethra sumatrana – SumatraClethra sumbawaensis – Lesser Sunda IslandsClethra symingtonii – PerakClethra talamancana – Costa RicaClethra tomentella – PhilippinesClethra tutensis – PanamaClethra tuxtlensis – VeracruzClethra uleana – S BrazilClethra vicentina – S Mexico, Central America