This is not a cactus. It looks like Euphorbia trigona to me. I have one I have had for a year now which has doubled in height since I got it, and is covered with leaves. I leave mine indoors all year and it has been thriving. I water it thoroughly in summer and very little in winter. Yours looks like it needs water to me, and maybe could use a repot and feeding. If there is any dead growth I would remove it also.

Christopher

Does it need a smaller pot? Or a bigger one? I know it's hard to see from the pics, but the tops of most of the stalks (?) have been broken off. And how do I remove the dead stuff? Sorry for all the questions, but I'm kind of new to all this plant stuff so why anyone would think I could save something is beyond me! : ) Thanks for your help!

Mama Shov,

A euphorbia is a great plant to grow, comes in hundreds of species and form, but all have latex that's potentially an irritant to toxic, so be careful, have some lukewarm water nearby to staunch the flow, wear gloves, a long-sleeved shirt and eye protection, at least until you know what you're doing, and even when you do.

Probably best to do this on the ground. Take the plant out, trim it up, and repot - in the same pot or different, but IMHO you have an appropriately-sized pot. Fresh porous soil will give it a chance to grow for the next few months until you have to bring it in for the winter.

How EXACTLY (and I do mean EXACTLY) do I trim it? I have no clue what I'm doing when it comes to most plants so I really need step by step instructions! Thank you very much for your help!!

Clean sharp knife, lukewarm water to staunch the flow of latex, protective gear, and away you go. Cut all the way to healthy tissue, and cut the branch to the trunk.