Question: Who are  native to the arid lands of Central and Northern Mexico, Caladium or Thelocactus ?

Context paragraphs:
Heliopetes ericetorum: Heliopetes ericetorum, the northern white-skipper, is a butterfly of the Hesperiidae family.  It is found in North America from eastern Washington south to western Colorado, southern California, Arizona and Baja California in northwestern Mexico.  The habitat consists of open woodland, chaparral, dry washes, desert mountains and arid lands.

Barbara Toy: Barbara Alex Toy FRGS (11 August 1908 – 18 July 2001) was an Australian-British travel writer, theatrical director, playwright, and screenplay writer.  She is most famous for the series of books she wrote about her pioneering and solitary travels around the world in a Land Rover, undertaken in the 1950s and 1960s.  Toy was drawn to deserts, and so the majority of her journeys were in the arid lands of Northern Africa and the Middle East.  Toy's first solo journey took place almost five years before the perhaps more celebrated six-man team Oxford and Cambridge Far Eastern Expedition, a London to Singapore overland trip between September 1955 and March 1956 that was also undertaken in Land Rovers.

Rattlesnake Mountain, Benton County, Washington: Rattlesnake Mountain (Native American name Lalíik meaning "land above the water") is a 3,527 ft (1,060 m) windswept treeless sub-alpine ridge overlooking the Hanford nuclear site.  Parts of the western slope are privately owned ranchland, while the eastern slope is under the federal protection of the Arid Lands Ecology Reserve, a unit of the Hanford Reach National Monument, managed by the United States Fish and Wildlife Service.

Thelocactus: Thelocactus is a genus in the cactus family, Cactaceae.  Members of the genus are native to the arid lands of Central and Northern Mexico.

Mount Grenfell: Mount Grenfell Historic Site is an Aboriginal rock art site, about 50 kilometres west of Cobar, in the arid lands in central west New South Wales, Australia.  It is a spiritually important place for its Aboriginal owners, the Ngiyampaa Wangaaypuwan people.  Hundreds of ancient rock drawings of humans, animals and the natural environment can be found at this historically invaluable site.

Peveril Meigs: Peveril Meigs, III, (May 5, 1903 – September 16, 1979) was an American geographer, notable for his studies of arid lands on several continents and in particular for his work on the native peoples and early missions of northern Baja California, Mexico.

Caladium: Caladium is a genus of flowering plants in the family Araceae.  They are often known by the common name elephant ear (which they share with the closely related genera "Alocasia", "Colocasia", and "Xanthosoma"), Heart of Jesus, and Angel Wings.  There are over 1000 named cultivars of "Caladium bicolor" from the original South American plant.

Eugraphe: Eugraphe is a genus of noctuid moths (family Noctuidae).  They belong to the tribe Xestiini of the typical noctuid subfamily Noctuinae, though some do not separate this tribe and include the genus in the Noctuini.  It is closely related to "Anagnorisma", "Coenophila" and "Eugnorisma", and as it seems most closely to the first of these (see also below).  The geographic range is Palearctic, north of the Alpides but including the Caucasus, and between the Arctic and the arid lands of Central Asia.

Drylands: Drylands are defined by a scarcity of water.  Drylands are zones where precipitation is balanced by evaporation from surfaces and transpiration by plants (evapotranspiration).  UNEP defines drylands as tropical and temperate areas with an aridity index of less than 0.65.  The drylands can be classified into four sub-types: dry sub-humid lands, semi-arid lands, arid lands, and hyper-arid lands.  Some authorities consider Hyper-arid lands as deserts (UNCCD) although a number of the world’s deserts include both hyper arid and arid climate zones.  The UNCCD excludes hyper-arid zones from its definition of drylands.

African collared dove: The African collared dove ("Streptopelia roseogrisea") is a small dove found in the Sahel, northern parts of the Horn of Africa and southwestern Arabia.  Although it lives in arid lands, it is found around water sources.

Supporting paragraphs: Thelocactus Caladium
Answer: Thelocactus