Cacti or Not?
Many succulents look like cacti, but are not
The name Cacti or Cactus has been adopted by the masses as the universal term to describe succulent plants. I have heard the term used to describe a varied range of plants from Euphorbia's to Fonquieria's (Ocotillo) to Agave's, Yucca's, & Aloe's.
Perhaps no other taxa is more commonly confused with true cacti than that of Euphorbia. Some Euphorbia's look more like a stereotypical cacti than even some cacti species. Euphorbia's can be found all over the world, but most originated in Africa. If you cut a Euphorbia, it will secrete a sticky, milky-white fluid. This fluid contains latex. Flowers of Euphorbias are typically small nondescript buttons with no sepals or petals. Many Euphorbia's also have thorns, making them appear even more similar to cacti. Upon closer inspection, however, one can easily see that these are not a separate spine arising from an areole like that of a true cacti.