Diversity, biogeography, and photosynthetic pathways of Argusia and Heliotropium (Boraginaceae) in South-West Asia with an analysis of phytogeographical units

摘要: South-West and Central Asia are major centres of diversity in the genus Heliotropium. On basis detailed taxonomic studies information gathered from literature, a synopsis 61 known species Heliotropium two Arguzia area is given. Iran, with 32 14 (sub)endemic species, has highest diversity. The photosynthetic pathways 42 taxa were determined using isotope composition method. Except for H. marifolium Retz s.l. H. rariflorum Stocks, all remaining analysed showed δ13C values characteristic C3 photosynthesis. Evidently, by contrast families Chenopodiaceae Polygonaceae, Irano-Turanian not an authochthonous region developing C4 distribution maps 57 provided their biogeographical importance discussed order to elucidate patterns Asia. In region, Irano-Anatolian province Zohary, which extends central Anatolia western Himalaya, very large vaguely defined phytochorion that should be split into smaller units. consideration southern Iran adjacent Pakistan as part Sudanian or Saharo-Sindian regions (sensu either Zohary Leonard) cannot accepted, because most endemic this typical isolated relicts. Furthermore, it concluded flora autochthonous flora; transgressive origin surrounding phytochoria. Finally, new ziegleri Akhani, described Iran. © 2007 Linnean Society London, Botanical Journal Society, 2007, 155, 401–425.