Autor: Lemaire

“Closed cactus” referring to the tubular flowers that open only very slightly.
A genus of shrubby plants with erect, often slender, cylindrical stems, shape variable, pendulous, prostrate, creeping or pending. Central and radial spines poorly differentiated.
Flowers diurnal, narrowly tubular, almost closed, more or less hairy, straight or slightly curved, yellow, orange, red to purplish red, pink, green, or sometimes bicoloured or even tricoloured, pollinated by hummingbirds. Fruits small, scaly, spherical, splitting when ripe. Seeds many, small, shinyrblack, globose to pyriform (pear-shaped), striate, often foveolate.
The genus Cleistocactus grows in dry, semi-arid woodlands, among thorny bushes, or in full sun, mainly in the Andes from 100 m up to 3000 m in altitude. The species found at higher altitudes (C. hyalacanthus, C. jujuyensis) are found in high valleys, in mineral, sometimes schistose substrates. Others (e.g. C. ritteri) live in deep valleys with a tropical climate. Some species such as C. baumannii are highly variable and a subspecies (C. baumannii subsp. horstii) lives at 100-200 m above sea level in an area near the Grand Pantanal wetlands in Brazil, where the average annual temperature is 25°C, and rainfall is than 1000 mm/year.
Argentina (Catamarca, Chaco, Cordoba , Corrientes, Entre Rios, Formosa, Jujuy, La Rioja, Salta , Santiago del Estero, Santa Fe, Tucuman), Bolivia (Chuquisaca, Cochabamba, La Paz, Potosi, Santa Cruz, Tarija), Brazil (Mato Grosso), Paraguay (Alto Paraguay, Boqueron, Concepcion, Cordillera, Paraguari, Presidente Hayes), Peru (Apurimac, Ayacucho, Huancavelica).

Currently 27 species (sensu strido + 7 subspecies) can be recognised:
– Cleistocactus ayopayanus Cardenas 1956
– Cleistocactus baumannii* (Lem.) Lem. 1861
– Cleistocactus baumannii subsp. chacoanus (F.Ritter) P.J.Braun & Esteves 1995
– Cleistocactus baumannii subsp. horstii (P.J.Braun) N.p.Tayior 1998
– Cleistocactus baumannii subsp. paraguariensis (F.Ritter) P.J.Braun & Esteves 1995
– Cleistocactus baumannii subsp. santacruzensis (Backeb.) P.J.Braun & Esteves 1995
– Cleistocactus brookeae Cardenas 1952
– Cleistocactus brookeae subsp. vulpis-cauda (F.Ritter & Cullman) Mottram 2001
– Cleistocactus buchtienii* Backeb. 1935 (= C. tupizensis)
– Cleistocactus candelilla Cardenas 1952
– Cleistocactus candelilla subsp. plraymirensis (cardenas) Mottram 2002
– Cleistocactus colademononis (Diers & Krahn) Mottram 2006
– Cleistocactus dependens Cardenas 1952
– Cleistocactus ferrari R.Kiesling 1984
– Cleistocactus grossei Backeb. 1957
– Cleistocactus hildegardiae F.Ritter 1980
– Cleistocactus hyalacanthus Backeb. 1942
– Cleistocactus jujuyensis (Backeb.) Backeb. 1942
– Cleistocactus lanlceps (K.Schum.) Gosselin 1904
– Cleistocactus luribayensis Cardenas 1956
– Cleistocactus morawetzianus Backeb. 1936
– Cleistocactus palhuayensis F.Ritter & Sahori 1980
– Cleistocactus parapetiensis Cardenas 1952
– Cleistocactus parviflorus* (K.Schum.) Gosselin 1904
– Cleistocactus pungens F.Ritter 1964
– Cleistocactus pycnacanthus (Rauh & Backeb.) Backeb. 1966
– Cleistocactus reae Cardenas 1957
– Cleistocactus ritteri* Backeb. 1959
– Cleistocactus smaragdifiorus* (F.A.C.Weber) Britton & Rose 1920
– Cleistocactus strausii* (Heese) Backeb. 1934
– Cleistocactus tominensis (Weing.) Backeb. 1935
– Cleistocactus tominensis subsp. micropetalus (Ritter) Mottram 2002
– Cleistocactus varispinus F.Ritter 1964 (= Cephalocleistocactus schottatianus)
– Cleistocactus viridiflorus Backeb. 1963

References: "TAXONOMY of the CACTACEAE" -  ISBN 978-84-617-3723-9 (Vol. 1)