* "Prickly Plant": This is the most common way to sign "cactus." You can do this by signing "prickly" (a handshape similar to the letter "P" with the index finger extended and moving like you're pricking something) and then "plant."
* "Desert Plant": You could sign "desert" and then "plant."
* Mimic the Shape: Depending on the type of cactus, you could use your hands to mimic its shape. For example, you could use your index finger and thumb to form a "V" shape to represent a saguaro cactus.
It's important to remember that sign language can vary depending on the region and the individual signer. If you're learning ASL, it's best to ask your teacher or a fluent signer for their preferred sign for "cactus."