Tropic trees for desert and or islands

I'm aware others have brought this up but it's a great idea since desert biomes only have cactus and sitcks now much foliage wise per had some tropical trees like the palm trees with coconuts and banana trees plus some flowers s that are also tropical in nature. I've seen also people suggesting volcanos as well what better to way to incorporate them in than with a tropical volcanic (dormant, active or both) island and kiwi fruit. Also random oasises in desert biomes as well