Cycads resemble palms, but are taxonomically quite different. They are a significant and irreplaceable component of the planet's biological diversity, having evolved various and often unique morphological, anatomical and biochemical features during their 250-million-year evolutionary history. Many cycad species exist today only as small, poorly-known or isolated populations or as ornamental species in botanic gardens. In order to understand fully, as well as to conserve, this internationally endangered tropical plant group, it is paramount that cycad systematics are studied, documented and refined. This volume presents the current state of our knowledge of the systematics of the approximately 300 species of cycads. It includes contributions from leading researchers from Australia, China, Italy, Mexico, South Africa, Thailand and the USA. It has been developed from papers presented at a workshop held in 2002, at the Montgomery Botanical Center.