Editing Cactus (section)

==Distribution==
[[File:Cactaceae distrib kz plus arrow.jpg|thumb|upright=1.5|Native distribution of cacti; {{legend|#18A9D6|''[[Rhipsalis baccifera]]'' only}} 
{{legend|#035D1F|All other cacti}}]]
[[File:Opunita Cactus Behbahan.jpg|alt=Opuntia Ficus-Indica in Behbahan, Iran|thumb|[[Opuntia ficus-indica]] in [[Behbahan]], [[Iran]]]]<!--[[File:Opuntia dillenii (Los Sauces) 01 ies.jpg|thumb|''Opuntia'' naturalized in the [[Canary Islands]]]]-->
Cacti inhabit diverse regions, from [[coastal plains]] to high mountain areas. With one exception, they are native to the [[Americas]], where their range extends from [[Patagonia]] to [[British Columbia]] and [[Alberta]] in western [[Canada]]. A number of centers of diversity exist. For cacti adapted to drought, the three main centers are the [[List of North American deserts|deserts of North America]]; the southwestern [[Andes]], where they are found in [[Peru]], [[Bolivia]], [[Chile]] and [[Argentina]]; and the [[Caatinga]] of eastern [[Brazil]]. Tree-living epiphytic and climbing cacti necessarily have different centers of diversity, as they require moister environments. They are mainly found in the coastal mountains and Atlantic forests of southeastern Brazil; in Bolivia, which is the center of diversity for the subfamily [[Rhipsalideae]]; and in forested regions of [[Central America]], where the climbing [[Hylocereeae]] are most diverse.{{sfnp|ps=none|Anderson|2001|pp=39–40}}

''[[Rhipsalis baccifera]]'' is the exception; it is native to both the Americas and the [[Old World]], where it is found in tropical [[Africa]], [[Madagascar]], and [[Sri Lanka]]. One theory is  it was spread by  being carried as [[seed]]s in the [[digestive tract]]s of [[Bird migration|migratory]] [[bird]]s; the seeds of ''Rhipsalis'' are adapted for bird distribution. Old World populations are [[polyploid]], and regarded as distinct subspecies, supporting the idea that the spread was not recent.{{sfnp|ps=none|Anderson|2001|p=611}} The alternative theory is the species initially crossed the Atlantic on European ships trading between South America and Africa, after which birds may have spread it more widely.<ref name=CotaBomf10/>

===Naturalized species===
Many other species have become naturalized outside the Americas after having been introduced by people, especially in [[Australia]], [[Hawaii]], and the [[Mediterranean region]]. In Australia, species of ''[[Opuntia]]'', particularly ''[[Opuntia stricta]]'', were introduced in the 19th century for use as natural agricultural fences and in an attempt to establish a [[cochineal]] industry. They rapidly became a major weed problem, but are now controlled by biological agents, particularly the moth ''[[Cactoblastis cactorum]]''.<ref name=weeds_australia/> The weed potential of ''Opuntia'' species in Australia continues however, leading to all opuntioid cacti except ''[[Opuntia ficus-indica|O. ficus-indica]]'' being declared [[Weeds of National Significance]] by the [[Australian Weeds Committee]] in April 2012.

The [[Arabian Peninsula]] has a wide variety of ever-increasing, introduced cactus populations. Some of these are cultivated,<ref name="Belgacem-et-al-2019" /><ref name="Prickly-pear-Saudi" /> some are escapes from cultivation, and some are invasives that are presumed to be ornamental escapes.<ref name="Faifa" /><ref name="Robai-et-al-2018" /><ref name="Hawagry-Dhafer-2014" />