text: Your question is ambiguous, that is not very clear. There are thousands of differernt orchid plants.They require different ecological condititions and hence their internal structure is not constant. It differs from species to species. Besides, how can one explain it with out a diagram? \nIn epiphytic orchids like Vanda or Acampe, the internal structure show plenty of water storage tissue and absence of palisade tissue.The epidermis is covered with thick cuticle.Epiphytic orchids are those that grow on other trees for support. They are not parasites.(22 Feb.2006)