Tree worship (dendrolatry) refers to the tendency of many societies throughout history to worship or otherwise mythologize trees. Trees have played an important role in many of the world's mythologies and religions, and have been given deep and sacred meanings throughout the ages. Human beings, observing the growth and death of trees, the elasticity of their branches, the sensitivity and the annual decay and revival of their foliage, see them as powerful symbols of growth, decay and resurrection. The most ancient cross-cultural symbolic representation of the universe's construction is the world tree.

The image of the Tree of life is also a favourite in many mythologies. Various forms of trees of life also appear in folklore, culture and fiction, often relating to immortality or fertility. These often hold cultural and religious significance to the peoples for whom they appear. For them, it may also strongly be connected with the motif of the world tree.

Other examples of trees featured in mythology are the Banyan and the Peepal (Ficus religiosa) trees in Hinduism, and the modern tradition of the Christmas Tree in Germanic mythology, the Tree of Knowledge of Judaism and Christianity, and the Bodhi tree in Buddhism. In folk religion and folklore, trees are often said to be the homes of tree spirits. Historical Druidism as well as Germanic paganism appear to have involved cultic practice in sacred groves, especially the oak. The term druid itself possibly derives from the Celtic word for oak.

Trees are a necessary attribute of the archetypical locus amoenus in all cultures. Already the Egyptian Book of the Dead mentions sycomores as part of the scenery where the soul of the deceased finds blissful repose. The evidence for tree-worship is almost unmanageably large, and since comparative studies do not as yet permit a concise and conclusive synopsis of the subject, this article will confine itself to some of the more prominent characteristics.

In almost every part of the world travelers have observed the custom of hanging objects upon trees in order to establish some sort of a relationship between themselves and the tree. Throughout Europe also, a mass of evidence has been collected testifying to the lengthy persistence of practices and beliefs concerning them. The trees are known as the scenes of pilgrimages, ritual ambulation, and the recital of (Christian) prayers. Wreaths, ribbons or rags are suspended to win favor for sick men or cattle, or merely for good luck. Popular belief associates the sites with healing, bewitching, or mere wishing; and though now perhaps the tree is the object only of some vague respect, there are abundant allusions to the earlier vitality of coherent and systematic cults. Decayed or fragmentary though the features may be in Europe.

Modern observers have found in other parts of the world more organic examples which enable us, not necessarily to reconstruct the fragments which have survived in the later religions and civilizations, but at least to understand their earlier significance. In India, for example, the Korwas hang rags on the trees which form the shrines of the village-gods. In Nebraska the object of the custom was to propitiate the supernatural beings and to procure good weather and hunting. In South America Darwin recorded a tree honored by numerous offerings (rags, meat, cigars, etc.); libations were made to it, and horses were sacrificed. If, in this instance, the Gauchos regarded the tree, not as the embodiment or abode of Walleechu, but as the very god himself, this is a subtle but very important transference of thought, the failure to realize which has not been confined to those who have venerated trees.

The tree, with its branches reaching up into the sky, and roots deep into the earth, can be seen to dwell in three worlds - a link between heaven, the earth, and the underworld, uniting above and below. It is also both a feminine symbol, bearing sustenance; and a masculine, phallic symbol - another union.

For this reason, many mythologies around the world have the concept of the World tree, a great tree that acts as an Axis mundi, supporting or holding up the cosmos, and providing a link between the heavens, earth and underworld. In European mythology the best known example is the tree Yggdrasil from Norse mythology.

The world tree is also a central part of Mesoamerican mythologies, where it represents the four cardinal directions. The concept of the world tree is also closely linked to the motif of the Tree of life.

Numerous popular stories throughout the world reflect a firmly rooted belief in an intimate connection between a human being and a tree, plant or flower. Sometimes a man's life depends upon the tree and suffers when it withers or is injured, and we encounter the idea of the external soul, already found in the Egyptian Tale of the Two Brothers of at least 3000 years ago. Here one of the brothers leaves his heart on the top of the flower of the acacia and falls dead when it is cut down. Sometimes, however, the tree is an index, a mysterious token which shows its sympathy with an absent hero by weakening or dying, as the man becomes ill or loses his life. These two features very easily combine, and they agree in representing to us mysterious sympathy between tree and human-life, which, as a matter of fact, frequently manifests itself in recorded beliefs and customs of historical times.

Thus, sometimes the new-born child is associated with a newly planted tree with which its life is supposed to be bound up; or, on ceremonial occasions (betrothal, marriage, ascent to the throne), a personal relationship of this kind is instituted by planting trees, upon the fortunes of which the career of the individual depends. Sometimes, moreover, boughs or plants are selected and the individual draws omens of life and death from the fate of his or her choice. Again, a man will put himself into relationship with a tree by depositing upon it something which has been in the closest contact with himself (hair, clothing, etc.). This is not so unusual as might appear; there are numerous examples of the conviction that a sympathetic relationship continues to subsist between things which have once been connected (e.g. a man and his hair), and this may be illustrated especially in magical practices upon material objects which are supposed to affect the former owner. We have to start then with the recognition that the notion of a real inter-connection between human life and trees has never presented any difficulty to primitive minds.

Often the tree is famous for oracles. Best known, perhaps, is the oak of Dodona tended by priests who slept on the ground. Forms of the tall oaks of the old Prussians were inhabited by gods who gave responses, and so numerous are the examples that the old Hebrew terebinth of the teacher, and the terebinth of the diviners may reasonably be placed in this category. Important sacred trees are also the object of pilgrimage, one of the most noteworthy being the branch of the Bo tree at Sri Lanka brought thither before the Christian era. The tree-spirits will hold sway over the surrounding forest or district, and the animals in the locality are often sacred and must not be harmed.

The custom of transferring disease or sickness from men to trees is well known. Sometimes the hair, nails, clothing, etc. of a sickly person are fixed to a tree, or they are forcibly inserted in a hole in the trunk, or the tree is split and the patient passes through the aperture. Where the tree has been thus injured, its recovery and that of the patient are often associated. Different explanations may be found of such customs which naturally take rather different forms among peoples in different grades.

In India, for example, when the patient is supposed to be tormented by a demon, ceremonies are performed to provide it with a tree where it will dwell peacefully without molesting the patient so long as the tree is left unharmed. Such ideas do not enter, of course, when the rite merely removes the illness and selfishly endangers the health of those who may approach the tree. Again, sometimes it is clearly felt that the main personality has been mystically united with some healthy and sturdy tree, and in this case we may often presume that such trees already possessed some peculiar reputation. The custom finds an analogy when hair, nail-clippings, etc. are hung upon a tree for safety, lest they fall into the hands of an enemy who might injure the owner by means of them.

Among the Arabs the sacred trees are haunted by angels or by jinn; sacrifices are made, and the sick who sleep beneath them receive prescriptions in their dreams. Here, as frequently elsewhere, it is dangerous to pull a bough. This dread of damaging special trees is familiar: Cato instructed the woodman to sacrifice to the male or female deity before thinning a grove, while in the Homeric poem to Aphrodite the tree nymph is wounded when the tree is injured, and dies when the trunk falls.

Early Buddhism decided that trees had neither mind nor feeling and might lawfully be cut; but it recognized that certain spirits might reside in them, such as Nang Takian in Thailand. Propitiation is made before the sacrilegious axe is laid to the holy trees; loss of life or of wealth and the failure of rain are feared should they be wantonly cut; there are even trees which it is dangerous to climb. The Talein of Burma prays to the tree before he cuts it down, and the African woodman will place a fresh sprig upon the tree. Some Ancient Indian tree deities, such as Puliyidaivalaiyamman, the Tamil deity of the tamarind tree, or Kadambariyamman, associated with the kadamba tree were seen as manifestations of a goddess who offers her blessings by giving fruits in abundance.

Trees were often regarded as sacred in the ancient world, throughout Europe and Asia. Christianity and Islam treated the worship of trees as idolatry and this led to their destruction in Europe and most of West Asia. In the manuscript illumination (illustration) Saint Stephan of Perm cuts down a birch sacred to the Komi people as part of his proselytizing among them in the years after 1383. His profanation of their shrines and cult images incurred their hostility.

Sacred trees remain common in India. They are found in villages, in the countryside and the heart of some temples (e.g. Jain temples). Plants are the only medium that connects the living and nonliving things in the environment. Every religion accepts the importance of trees. Hence worship of trees was in existence from the ancient times. Eco Worship is the Worship of Environment through plants. Shripad Vaidya of Nagpur, Maharashtra was founded Eco-Worship Center (NAKSHATRAVAN). It is the First in the world and is known for Worship of Environment through plants. The Indian 'shastras' and 'panchang', too mention several ways of doing so, one of them being offering prayers to various trees.

In Sri Lanka, Buddhists worship the Bodhi Tree. It is said to have protected the Buddha when he was meditating to attain enlightenment. The Glastonbury Thorn in Glastonbury, England is a small Common Hawthorn tree regarded as sacred by many Christians. It is said to have sprouted miraculously from the staff of the early Christian figure Joseph of Arimathea. Of further religious significance and indeed scientific interest, the tree displays a rare phenomenon for its species, blooming not once but twice per year. The second bloom occurs around the holiday of Christmas.