Included here are the mountains and coastal plain extending in a crescent around the south and southwest parts of the Caspian Sea.

Hyrcanian Alnus-Pterocarya Forest

These ancient yet ill-defined forests are confined mostly to damp and poorly drained soils on the coastal plain. They are characterized by the near endemic Alnus subcordata (Betulaceae) and Pterocarya fraxinifolia (Juglandaceae). Common associates include Acer insigne, Albizia julibrissin, Alnus glutinosa, Buxus sempervirens, Celtis australis, Diospyros lotus, Ficus carica, Fraxinus excelsior, Melia azedarach, Mesilus germanica, Morus nigra, Paliurus spina-christa, Prunus laurocerasus, Punica granatum and Salix fragilis, while common endemic or near endemic species are Gleditsia caspica (Fabaceae), Populus caspica (Salicaceae), and Prunus caspica (Rosaceae). The shrub layer comprises Andrache colchica, Hypericum androsaemum, Sambucus edulis and several endemic taxa like Epimedium pinnatum subsp. pinnatum (Berberidaceae), Ruscus hyrcanus (Liliaceae) and Teucrium hyrcanus (Lamiaceae). These forests are also characterised by the presence of numerous lianas and climbers, which occur on many of the trees and shrubs - typical species are Clematis vitalba, Hedera colchica, Jasminum officinale, Peroploca graeca, Rubus caesius, Smilax excelsa, Solanum dulcamara, Tamus communis and Vitis sylvestris.

References

Browicz, K. 1987. Chorology of the Euxinian and Hyrcanian elements in the woody flora of Asia. Plant Systematics and Evolution, 162: 305-314.

Frey, W. & Probst, W. 1986. A synopsis of the vegetation of Iran. In: Contributions to the Vegetation of Southwest Asia. Ed. H. K├╝rschner. Dr. Ludwig Reichert Verlag.

Hedge, C. & Wendelbo, P. 1978. Patterns of distribution and endemism in Iran. Notes of the Royal Botanic Garden, Edinburgh, 36: 441-464.

Heshmati, G. A. 2007. Vegetation characteristics of four ecological zones of Iran. Journal of Plant Production, 1: 215-224.

Zohary, M. 1971. The Phytogeographical Foundations of the Middle East. In: Plant Life of South-West Asia. Eds. P. H. Davies, P. C. Harper & I. C. Hedge. The Botanical Society of Edinburgh.

Zohary, M. 1973. Geobotanical Foundations of the Middle East. Volumes 1 & 2. Gustav Fischer Verlag, Stuttgart & Swets & Zeitlinger, Amsterdam.

Zohary, M., Heyn, C. C. & Heller, D. 1980. Conspectus Florae Orientalis. The Israel Academy of Science and Humanities. Jerusalem.