Question

how do subs and some trees survive in hot desert?

Answer 1

they adopt the environment or habitat and also they mostly have spikes over them to prevent water loss and a thick waxy coating of cutin as to prevent the loss of water by the process of transpiration

Answer 2

Dear mate,
Here's your answer...
Shrubs and some trees in desert survive by adapting the habitat around them. For example, cactus ( a thorny shrub in desert) have thorns that help it to avoid water loss that happens by transpiration. The trees found in the desert have thick coated body which help them to resist the hot temperature.
Hope it helps you !!