A REVIEW OF THE GENUS ALNUS GAERTN. IN IRAN, NEW RECORDS AND NEW SPECIES

The genus Alnus Gaertn., with approximately 20 species, is of great economic importance and some of the species are as the source of timber in the north hemisphere. In the Hyrcanian forests, the trees of this genus have many critical roles especially in forest rehabilitation. Like most of woody plants in Hyrcanian forests, there are many taxonomic problems concerning the recognition of the species of the genus Alnus in Iran. To cope with, during the long term study on the trees of this genus in the most parts of Hyrcanian forests, many specimens of these trees in the field and in different sites were collected. The studies were performed on living and herbarium specimens and some of the most important local herbarium materials were studied too. According to the previous studies, the genus Alnus in Iran includes two species: Alnus glutinosa Gaertn. subsp. barbata (C. A. Mey) Yaltrik and Alnus subcordata (C. A. Mey.) Yaltrik with two varieties which are distributed in Hyrcanian forests. The results obtained from many specimens of Alnus revealed that there are three extra species and records including: Alnus djavanshirii Zare, Alnus dolichocarpa Zare, Amini & Assadi and Alnus orientalis Decne. as well as two subspecies viz. Alnus glutinosa Gaerth subsp. glutinosa and Alnus glutinosa Gaerth subsp. antitaurica Yaltrik. In this paper, botanical characteristics and ecology of the taxa are elaborated.