Trees specially evergreens and ancient trees are the symbol of Immortals in Zoroastrianism. The link between trees, “Immortality and deathlessness” ameretát is established in the poetic gathas, See Yasna 51.7.
The original gathic poetry reads as follows: apas-čá ûrvarávs-čá ameretátá haûrvátá. Here the word for “tree” is ûrvar, and the word for “immortality, deathlessness” is ameretát.
Avestan ûrvará “tree” is a cognate of Latin arbor “tree.” Other cognates are Latin arvus “ploughed field,” and Mycenaean Greek aroura “arable land.”
Trees also come in close connection with “prophetic vision and oracles” in the Avestan poetry. The süd-kar gathic commentary of Yasna 31.5 narrates the vision of an immense tree with four branches, of gold, silver, steel, and “mixed-up” iron, which symbolize the four future ages of this world.
The “mixed-up” iron symbolizes the present age of admixture that is the calamitous age of invasion/contamination by demons.
An Avestan passage in Yasht/hymn 12/17, praises the tree of the great mythical “falcon or eagle” saæna that stands in the middle of the “wide-shored ocean” vôúrú-kašahæ.
The eagle/falcon tree is a wondrous evergreen that keeps away decrepitude and death. It is called all healing with good and potent medicine. The seeds of all medicinal plants are deposited on it.
Saæna “falcon, eagle,” of the Avesta, is the mythical bird of Persian Mythology Sīmorḡ who is said to perch every year on this sacred tree located in the middle of wide-shored ocean, to mix its seeds with pure waters, which Tištar (Three-star, Sirius) then rains down on all the 7 climes of the earth, thus causing the growth of all kind of healing plants.
The Avestan saæna, Persian Sīmorḡ is a cognate of Sanskrit śyená. The Russian word for “falcon” sókol is a borrowing from the same word in ancient Iranian.
In the Avestan Yašt/hymn 14.41 Vərəθraγna, the god being of VICTORY, wraps xᵛarnæ, “glory, good fortune,” round the house of the worshipper, in the same way that the great falcon/eagle Saæna, cover the great mountains like the clouds.
In Zoroastrian religious ceremonies, “small branches or twigs” of an evergreen (mostly cypress trees) or fruit tree (usually pomegranate) called barəsman, form an important part of the sacred ritual. Barəsman is derived from the root barəz “to grow high.” German berg “high” is a cognate.
Barəsman “sacred twigs” are one of the requisites of a “fire priest,” Āθravan (See Vendidad 14.8,) and constitute an essential ritual implement for various liturgical services such as yasná “yearning, longing” (Greek zelós is a cognate,) and afrîn prayers, literally “loving charms” that are Avestan benediction formulas.
The Persian word for tree is draxt also dár ó draxt. The word comes from the Avestan daûrû going back to the reconstructed Proto Indo European *dóru, and is a cognate of Russian дерево (dérevo); Polish drewno; Greek δόρῠ (dóru); Gothic triu; Old English trēow “tree,” (See Didier Calin, Encyclopedia of Indo European poetic and religious themes.)
Trees in Mazdyasna “Mazda worshipping religion/Zoroastrianism” are sacred, and embody immense and enduring life and deathlessness of consciousness.
Sarv-e Abar kuh, literally the Cypress tree of the über-mountain also called the “Zoroastrian tree,” is a cypress tree in Central Yazd province of Iran. The tree is estimated to be at least 4,000 years old and believed to have witnessed the dawn of ancient Iranian civilization.
Herodotus (7.31) reports that at Callatebus in Asia Minor, the Achaemenid Xerxes (486-65 B.C.E.) found a plane tree so beautiful that he decorated it with golden ornaments and put it under the care of one of his Immortals.
The sacred attitude toward venerable trees has continued in Iran to the present day, but with the transfer of devotion from Zoroastrian Immortals to Twelver Shiʿite Saints.
Often, the very pine and cypress trees that had flanked Zoroastrian fire temples in the Sassanid period continue to shade the tombs of emāmzādas and other shia saints today.
In general, however, Iran has suffered from continuous, great deforestation over the centuries after the arab invasion.
Sanctity of trees in Zoroastrianism meant legal sanctions against profaning or destroying them in the Mazdean Jurisprudence. Such legal protections for trees did sadly not continue into the Islamic age. Yet the folk belief that anybody felling a tree will be short-lived, and cuts on his/her good fortune goes back to the deep-rooted ancient religion of the Iranians.