What is a Green Man ? Apparently it is not so easy to give a definition. On the internet there are many visions of what a Green Man is or is supposed to be. Since the 1970's or a little later, the interest of people was aroused in the subject and the opinion of what a Green Man is varies from "any head, human or animal alike, engulfed in leaves" to "heads out of which branches with leaves appear, no matter from what part of the head".
Other interesting questions are : What is the origin of the Green Man ? What is the meaning of a Green Man ? That the Green Man did have a specific meaning in the church may be clear further in this article.

The origin, the meaning and its purpose is regretfully unknown as there is no documentation. It is a bit like it is with the labyrinth, guesses, myths. All we know is that the phenomenon of heads from which leaves originate, is very, very old and existed long before the Christian Era. These heads are known to appear in India and Nepal before temples, also in Indonesia. The heads were supposed to keep evil away and therefore they were not only used in and outside temples and churches but also outside common homes.

The name "Green Man" was re-introduced in 1939 by Lady Raglan in an article in The Folklore Journal titled "The Green Man in Church Architecture". At the time Lady Raglan was very interested in various features of folklore and their origin. Eight years earlier the vicar of the church in Llangwm called on her and asked her if she knew what the sculpture on a corbel in the church meant. When Lady Raglan saw the sculpture, she said that it was a Green Man. How did she know this name ? There exists documentation that the name "Green Man" has been used several ages earlier.

The Green Man in the church should not be confused with the folklore character Jack-in-the-Green, though sometimes one is tempted to do so.
Lady Raglan connected Jack-in-the-Green to the May festival, a festival that is popular at times but a festival that did not exist in the 14th century as was shown by Roy Judge in 1975 in his work "The Jack in the Green, a May Day Custom". The earliest Jack in the Green procession dates from 1795.

The term Green Man, re-introduced by Lady Raglan, refers to the sculpture found in the church of Llangwm (Wales, United Kingdom) and in her article also the head on the font of Stow Minster is mentioned of which it can be safely said that it is not related to a May Day Custom. The Green Man has leaves that originate from the mouth and later also from other parts of the head. The same is true for the Green Man of Melrose she mentioned. The Green Man enormously gained in interest and soon any head or person engulfed in leaves is unjustly called a Green Man. Example : a statuette of a Roman victor with a laurel, that is not a Green Men. Also the roof boss below is not a Green Man as it is Christ with a nimbus with cross.

Leaves or vegetation is a very important symbol in the church and can be seen in the sculpture of churches of all ages as well as in windows. Leaves are a symbol of life, eternal life if you wish. In the older heads the leaves or branches with new leaves originate in the mouth. Two, one at either side. Thus the leaves tell us an important story. A head with leaves thus described, is nowadays called a Green Man.
Below there are shown several Green Men and how their appearance changed with time. In some cases three branches with leaves originate from a mouth as in the church of Burgh-le-Marsh in England (further down on this page). When looking for a Green Man in churches, you find heads where the leaves originate from all possible places on the head, for instance the nose or the cheek or the forehead or even the eyes. Why ? The answer is unknown because there is no documentation whatsoever on the how and why of this phenomenon. A lot has been written, mostly guess work and nothing has been proved. The explanation that the leaves are a symbol of life makes sense in Christian life and in other religions or beliefs.
The figures in the window of Léon Cathedral - see picture above - are not to be considered as Green Men. If you look carefuly, you see they are bishops with mitres on their heads. Mitres with a cross. There are many, many of these bishops in a lancet window. The leaves ? Well, that makes sense according to the explanation above or they are there as decoration. Decoration ? Could that be the reason of the existence of foliated heads at the beginning of this page ? Did the real meaning get lost through the ages as there is no documentation ?
In 1563 the Council of Trent ended after many years of deliberation. It was a council of the Roman Catholic Church and the ideology of Faith deepened and rules for behaviour were laid down. Under these new rules the artistic freedom in art was thus severely restricted, for example, the making of Green Men was discouraged. Henceforth the making of Green Men came, more or less, to a halt. In the United Kingdom however, there was no such discouragement because of the separation from the Roman Catholic Church when Henry VIII pronounced himself head of the Church of England. Nowhere else in the world the Green Man flourished so abundantly.

You can safely say that originally heads were to deter evil and these heads were animal heads, inside and also outside churches. Was this a continuation of pagan rites ?
See examples below.

The sarcophagus of Sainte Abre, daughter of St Hilaire, can be found in the romanesque church St Hilaire in Poitiers, France. St. Hilaire was bishop of Poitiers from 352 to 368. The church was built over the sarcophagus of St Hilaire, and was an important centre of pilgrimage. However, the church suffered several destructions, that is in 732 by the arabs and in 863 by the vikings. The church of today dates from the 11th century.
The sarcophagus of Sainte Abre was discovered in 1762. Decorated in a style of the end of the 4th century or early 5th century. The head is clearly roman, judged by the leaves around the head. Also here new leaves sprout from the nostrils. Is this the oldest surviving example of a Green Man in a church ?