Clethra is a genus of flowering shrubs or small trees erected as a genus by Linnaeus in 1753.Linnaeus, Carl von. 1753. Species Plantarum 1: 396 in LatinTropicos, Clethra L.
Clethra is one of two genera in the family Clethraceae (the other being Purdiaea). The species may be evergreen or deciduous, and all bear flowers in clusters (inflorescences), 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 (C. arborea) on the Atlantic 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.Angiosperm Fruits and Seeds from the Middle Miocene of Jutland (Denmark) by Else Marie Friis, The Royal Danish Academy of Sciences and Letters 24:3, 1985
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)Flora of China Vol. 14 Page 238 桤叶树属 qi ye shu shu Clethra Linnaeus, Sp. Pl. 1: 396. 1753. 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 (Alabama to Pennsylvania) Clethra alcoceri – Hidalgo, Jalisco Clethra alexandri – Jamaica Clethra alnifolia – sweet pepper bush or summer sweet; S + E United States (Texas to Maine) Clethra arborea – lily of the valley tree; Madeira, Canary Islands†, Azores Clethra arfakana – New Guinea Clethra barbinervis – Japanese sweet shrub; SE China, Korea, Japan Clethra bodinieri – S China Clethra canescens – Philippines, E + C Indonesia, New Guinea var. clementis – Borneo Clethra castaneifolia – Peru Clethra chiapensis – Chiapas Clethra consimilis – Panama, Costa Rica Clethra conzattiana – Oaxaca Clethra crispa – Ecuador Clethra cubensis – Cuba Clethra cuneata – Peru, Bolivia Clethra delavayi – SW China, Assam, Myanmar, Bhutan, Vietnam Clethra elongata – Peru, Bolivia Clethra fabri – S China, Vietnam Clethra fagifolia – Ecuador, Colombia, Venezuela Clethra fargesii – C China Clethra ferruginea – Peru Clethra fimbriata – Peru, Ecuador, Colombia Clethra formosa – Costa Rica Clethra fragrans – Jalisco, Michoacán, Guerrero Clethra galeottiana – Puebla, Oaxaca, Chiapas Clethra gelida – Costa Rica, Panama, Honduras Clethra guyanensis – Guyana, Venezuela Clethra hartwegii – C + S Mexico Clethra hendersonii – Peninsular Malaysia Clethra hirsutovillosa – Guerrero Clethra hondurensis – Tabasco to Costa Rica Clethra javanica – Java, Bali, Lombok, Timor Clethra kaipoensis – SE China Clethra kebarensis – New Guinea Clethra licanioides – Guatemala, Honduras Clethra longispicata – Borneo, Philippines, Sulawesi, Maluku Clethra luzmariae – Oaxaca Clethra macrophylla – Veracruz, Puebla Clethra mexicana – C + S Mexico, Central America, Colombia, Venezuela, Trinidad Clethra oaxacana – Oaxaca Clethra obovata – Ecuador, Peru Clethra occidentalis – Jamaica Clethra oleoides – C + S Mexico, Central America Clethra ovalifolia – Colombia, Venezuela, Ecuador, Peru Clethra pachecoana – Chiapas to Honduras Clethra pachyphylla – Borneo Clethra papuana – New Guinea Clethra paralelinervia – Ecuador Clethra × parvifolia – Chiapas Clethra pedicellaris – Colombia, Ecuador, Peru Clethra peruviana – Ecuador, Peru Clethra petelotii – Vietnam, Yunnan Clethra poilanei – Laos Clethra pringlei – Mexican summersweet – Mexico Clethra pulgarensis – Palawan Clethra purpusii – Oaxaca, Chiapas Clethra pyrogena – Panama, Costa Rica Clethra repanda – Colombia, Venezuela Clethra retivenia – Peru Clethra revoluta – Colombia, Bolivia, Ecuador, Peru Clethra rosei – Mexico Clethra rugosa – Colombia, Ecuador Clethra scabra – Brazil, Bolivia, Paraguay, NW Argentina Clethra skutchii – Guatemala Clethra sleumeriana – Hunan Clethra suaveolens – S Mexico, Central America Clethra sumatrana – Sumatra Clethra sumbawaensis – Lesser Sunda Islands Clethra symingtonii – Perak Clethra talamancana – Costa Rica Clethra tomentella – Philippines Clethra tutensis – Panama Clethra tuxtlensis – Veracruz Clethra uleana – S Brazil Clethra vicentina – S Mexico, Central America
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