This plant genus was one of the main reasons for our journey to Iran and Oman in 2003.
After our first visit to Iran in 2000, we became more and more interested in this fascinating genus. Around 50 species are known up to now, most of which are found in Iran and Afghanistan only. Most species grow on limestone, usually vertically under overhanging rocks in narrow crevices. Most species in Iran grow in the Zagros mountains, a mountain chain running from the northwest of Iran in southeast direction towards the city of Shiraz. Also further east in some isolated mountians and in the northern Alborz range a few Dionysia species are found. In Oman only one species grows, its Dionysia mira which can be found on the highest summits of Jebal Akhdar. During our 3 months stay in Iran in 2003 we found 15 species of Dionysia, most of them flowering. We also found Dionysia mira in Oman.
If you want more information about this fascinating genus, consider purchasing the book written by Chris Grey-Wilson: The genus Dionysia and published buy the AGS.(unfortunately not longer for sale from the AGS, but sometimes offered by Amazon.com)
Or read this article by Magnus Liden.