Hehe the Marlothii is just a baby of about 7 years old and they can grow long stems and turn into trees

I know cacti would look good but so many become invaders here, especially if it has cereus in the name, so I keep mine in pots.
The yellow-flowered euphorbia is cactiformis
The little one is Euphorbia trichadenia, it's a grassland caudiciform native to my area. I had it in a pot in the greenhouse but it kept getting spider mites so I put it where it will be happy