I have a curiosity about Islamic Gardens, especially their symbolism and design. Unlike western gardening concepts, Islamic Gardening hedges on sacred worship.  Many of the greatest gardens were built to symbolize Paradise, and they included items referenced in the Quran.  Quite amazing if you think about it.  The best example would be the Taj Mahal,

It’s unfortunate that so many of these wonderful gardens have fallen into disuse due to a lack of interest.  Among the few Western books on the subject, I found a few worth looking at:

1. Islamic Gardens and Landscapes.  An explanation of Islamic Gardens.  The symbolism used, History and current status.  Basically a text explaining these types of Garden.  Quite hard to find, and expensive.
2. 

   The Art of the Islamic Garden

   The Art of the Islamic Garden By Emma Clark.  An in depth look at Islamic Gardens, their theory and practice.

3. 

   Gardens of Paradise: The History and Design of the Great Islamic Gardens

   by John Brookes

4. 

   Gardens of Delight: The Great Islamic Gardens

   By Christa Van Hantelmann .  A look at existing Islamic Gardens.  Their history, layout and analysis of design.
   

5. Underneath Which Rivers Flow: The Symbolism of the Islamic Garden By Emma Clark.  The second book by Emma.
   
6. 

   Gardens, Landscape, and Vision in the Palaces of Islamic Spain

   by D. Fairchild Ruggles.  Another theoretical book about Islamic Gardens in Spain.

7. 

   Islamic Aesthetics: An Introduction

   An interesting book that looks at Islamic Art from the aesthietic point of view.  Not religious point of view.