Opuntia streptacantha. I think I had one of these growing on my window sill in college, but not as a tree.
Aeonium arboreum. This could be the star of the latest Alien movie. Is this a plant?
Could this be a sunburned aloe?
Furcraea macdougalii. These poor souls from the agave family looked scared.
Dracaena draco. This is a dragon tree - no one can figure out why it's called that. :-)
Crassula falcata. One of the only flowering specimens in the garden.
Sunburn anyone? A 5-foot tall (1.5 m) aloe can help.
And one last cactus, only 6-feet tall (1.8 m) because I believe it fell over.