Epidermis-4 

The Epidermis of flowering plants produces a wide array of hairs or Trichomes. They range from simple cells to elaborate,multi cellular, organ-like structures. Their adaptive significance is truly great, and many of their features are crucial for life on land. In some cases the relationship between plants and animals, as well as microbes is mediated by epidermal hairs. Young leaves are often covered with Trichomes. These may be ephemeral or persistent. They  provide protection for these primordial structures.

The most familiar, and most simple Trichomes are root hairs! These are under-appreciated in terms of their functional significance. They are single cells that greatly increase the absorptive surface area of roots. The most notorious interrelationship of root hairs and microbes occurs in  the legume-Rhizobium symbiosis. The root hairs are the initial recognition sites for the attachment of the nitrogen-fixing bacteria.