PlantFiles: Dune Aloe
Aloe thraskii

Another spectacular tree aloe, doing very well here in northern regions of coastal New Zealand, tolerating some frost and growing to astonishing proportions in our wet winters, so dont be afraid to plant this in a high-rainfall area. Will handle very harsh sunlight, sometimes taking on a coppery leaf sheen (we basically have no ozone layer down here so UV levels are off the scale, probably worse than anyone in the US would experience.)
Grows on steep slopes in native habitat, so a great choice for a hillside garden, roots being very tenacious. Birds adore the flowers.

Down here in Dunedin (admittedly at the very edge of their viable range) I have had a lot of trouble getting them beyond the juvenile stage, even in pots. Which is maddening, because they're pretty tough once they're past a certain size. I know of no particular reason for these failures, and have little problem growing (theoretically) more tender tree aloes- vaombe, vaotsanda, rupestris; I have a large barberae in the ground, darn it!
And I'm not alone in this, judging from interweb reports.

If you can grow them, lucky you and please don't take them for granted.

Majestic tree aloe with profuse, thick, yellow-orange flowers in mid winter. Has tyipcal arching, grooved aloe leaves with light green coloration. Can be confused with Aloe vanballenii when young, and Aloes angelica and alooides as mature plant. Flowers look different, though. Pretty fast grower and appreciates a lot of water in warmer weather (tolerates water in cold winters, too, in well draining soil). South AFrican native.

Eventually these seem to get too tall, and all eventually fall over. Most of these show signs of root or trunk rot. They either outgrow their food supply, stems get too tall to transport stuff back and forth, or roots rot.