Ferns and fern allies of Iran.
The pteridophyte account of Flora Iranica (ed. K.H. Rechinger) is still not published. The Caspian forests provide suitable habitats for the growth of many ferns and fern allies in Iran. In semi-arid and mountainous areas of Iran, mesophilous plants are restricted to rock crevices, waterfall proximity, stream banks and lake shores. Based on field collections and study of herbarium specimens in Iranian herbaria, an updated and annotated inventory of the Iranian ferns and fern allies is provided with an identification key, original line-drawings and/or photographs of most species, and distribution maps. Altogether 52 species are known in 26 genera and 15 families, viz. Ophioglossaceae (4), Psilotaceae (1), Equisetaceae (4), Osmundaceae (1), Marsileaceae (1), Salviniaceae (2), Dennstaedtiaceae (1), Pteridaceae (11), Aspleniaceae (8), Thelypteridaceae (2), Woodsiaceae (4), Blechnaceae (1), Onocleaceae (1), Dryopteridaceae (9) and Polypodiaceae (2). The intriguing discovery of Psilotum nudum is discussed with regard to its habitat and shoot anatomy. Cystopteris fragilis subsp. dickieana, as a new record, and the occurrence of Polystichum lonchitis, Pteris vittata and Ophioglossum polyphyllum in Iran are confirmed. Azolla filiculoides is a recently introduced invasive plant widely spread in the Anzali wetland and other aquatic habitats in N Iran. Several doubtful records are excluded from the pteridophyte flora of Iran.