Question

why is vegetation in sahara have long roots

Answer 1

this is because the sahara region has hot and humid climatic conditions due to which they have turned out deserts,so the roots have to penetrate much deep to absorb water .....so they have long roots

Answer 2

sahara is a hot region and as roots are hydotropic and gravitropic they respond to the stimulus of water .i.e they move towards water .in short they grow towards water or in search of water