Oreocereus

The species of the genus Oreocereus grow shrubby, branching only sparsely from the base and reach heights of growth of 2 to 3 meters. Trunks are rarely formed. The erect, pendulous or rarely extended cylindrical shoots are notched or warty between the ribs. The areoles often have long white hairs and dense spines. As they are covered with woolly white fuzz (modified spines), a few species in this genus are sometimes known as the old-man cactus,University of Vermont, [http://pss.uvm.edu/pss123/cacesp.html Indoor Plants]{{cite book|author1=Barry Walker|author2=Huw Lloyd|title=Peruvian Wildlife: A Visitor's Guide to the Central Andes|url=https://books.google.com/books?id=fWFHDhLnylAC&pg=PA23|year=2007|publisher=Bradt Travel Guides|isbn=978-1-84162-167-8|page=23}} a generic name that also refers to Cephalocereus senilis or Espostoa lanata. More rarely, the old man of the mountain is also used for some species.{{refn|group=nb|“[...] hairy cacti in cultivation include: golden old man (C. chrysacanthus), old woman (Mammillaria hahniana), Chilean old lady (Neoporteria senilis), and old man of the mountain (Borzicactus trollii).”Encyclopædia Britannica (1991), entry ‘old-man cactus’. [emphasis added, B. trollii being an old name for O. trollii].{{cite book|author=D. J. Mabberley|title=Mabberley's Plant-book: A Portable Dictionary of Plants, Their Classifications, and Uses|url=https://books.google.com/books?id=9RyKKHtwXUYC&pg=PA608|date=2008-05-01|publisher=Cambridge University Press|isbn=978-0-521-82071-4|page=608}}}}

The tubular to funnel-shaped, more or less radially symmetrical, orange to red to violet flowers arise near the shoot tip, or sometimes from the terminal cephalium, and open during the day. The flower-tube is straight to slightly curved and sometimes laterally compressed. The numerous areoles on the pericarpel and the flower tube are hairy. The spherical to oblong fruits contain broadly oval, dull or shiny black seeds.{{cite book | last=Backeberg | first=Curt | title=Die Cactaceae | date=January 1984 | isbn=3-437-30383-X | language=de | pages= 2619–2629| publisher=Fischer }}{{cite book | last1=Anderson | first1=Edward F. | last2=Eggli | first2=Urs | title=Das grosse Kakteen-Lexikon | date=2005 | isbn=3-8001-4573-1 | language=de | page=482| publisher=Ulmer }}

{{As of|2023|September}}, Plants of the World Online accepts the following species:{{cite web | title=Oreocereus Riccob. — Plants of the World Online | website=Plants of the World Online | date=2020-02-03 | url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30004843-2 | access-date=2023-09-29}}

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• {{Commons category-inline|Oreocereus|Oreocereus}}
• {{Wikispecies-inline|Oreocereus|Oreocereus}}

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Category:Cereeae

Category:Cacti of South America

Category:Flora of the Andes

Category:Cereeae genera