Echinocactus platyacanthus

Echinocactus platyacanthus, also known as the giant barrel cactus, golden barrel cactus, giant viznaga, or biznaga de dulce, Its Nahuatl (Aztec) name is  Huitzli nahual. It is a species of cactus (family Cactaceae). It is native to central Mexico in the Chihuahuan Desert. This species is the largest of the barrel cacti. In Mexico the hairs are often used for weaving; the acitrón, a traditional Mexican candy, is produced by boiling the pith.

Description
This slow-growing species can reach sizes up to 2.5 m tall and 1.5 m wide and can live over a hundred years. Photographs exist of specimens almost four feet (almost 1.2 m) in thickness. What is probably the largest individual living today is the one called "Goliat" at the "Area natural de Daxpe" in the municipio de Cadereyta, Querétaro State, Mexico, which is 9' 8"  (2.95 meters) in height, at least three feet (0.9 meter) thick and weighs about three metric tons (6,600 pounds). Another at Ixmiquilpan, Mexico has a measured diameter of 3 ft 11 in (120 cm) and is 7 ft 10 in (2.4 meters) high. Britton and Rose reported a specimen  (with photograph) which was 1.33 meters (4 ft 1in) thick, by ten feet (three meters) in height and weighed 4,400 pounds (2,000 kilograms).

Their stems are a gray-ish blue color and the straight, rigid spines are black. The apex of the cactus is flat and covered with a yellow felt-like substance. They are heavily ribbed, with 25 to 30 vertical ribs, and have large areoles. Their diurnal, tubular flowers bloom at the end of spring to summer and are a vivid yellow color; they grow to about 2 cm in height and 3 cm in width. The fruit is about 3 cm long and is covered by a hairy wool.