Photographer Beth Moon's black and white images celebrate the diversity of ancient trees

The San Franciscan has travelled across the US, to Europe, Asia, the Middle East and Africa in search of her subjects, which must meet one of three criteria: age, immense size or notable history

'Heart of the Dragon': This tree can be found in Socotra, an island off the Horn of Africa, and bleeds a scarlet sap when its trunk is cut (Beth Moon)

It was while she was living in London 15 years ago that the American photographer Beth Moon first found herself enthralled by trees. "There were so many impressive ancient ones right there and I started to visit different ones all around the city. I just wanted to chronicle their existence."

Since then the 59-year-old San Franciscan has travelled across the US, to Europe, Asia, the Middle East and Africa in search of her subjects. The trees she chooses to photograph must meet one of three criteria: age, immense size or notable history.

She researches them using botanical books, tree registers and newspapers. On arrival, Moon will examine the tree carefully, claiming that they, just like humans, have a good side.

Her images of these otherworldly sentinels celebrate the diversity of trees. Of those seen in the gallery above, "Heart of the Dragon", which can be found in Socotra, an island off the Horn of Africa, bleeds a scarlet sap when its trunk is cut; the Great Western Red Cedars of Gelli Avr, Wales, are believed to have been planted in the 1860s; and the entwined baobabs of Madagascar are nicknamed "The Lovers" by locals.

Moon's decision to shoot in black-and-white has produced striking results. "There's a lot of distraction with colour," she says. "What I'm looking for in the trees is geometry of form.

"Anyway, for me they show quite the range of colour, from warm browns to cool blacks. Others might see them as black-and-white, but I don't."

'Ancient Trees: Portraits of Time' is published by Abbeville Press, priced $49.95. For more information: bethmoon.com