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Wednesday, 29 November 2006

Ginkgo

Ginkgo biloba is a very unusual tree. It is believed to be the only surviving species from a group of trees which had their heyday 200 million years ago. Taxonomically speaking, the ginkgo is about as closely related to the oak as human beings are to reptiles.

Autumnal ginkgo leaves in Sheffield Botanical Gardens © Roger Butterfield

The tree itself may not be not much to look at, but its fan-shaped leaves are unique. At this time of year they turn a stunning shade of yellow. After a sharp frost it is not unusual for them to fall en masse, forming a brilliant carpet beneath the tree.

On a recent visit to Sheffield Botanical Gardens I noticed that the fallen leaves of ginkgo have an unusual property. Each leaf is divided by many closely-spaced veins, which radiate out from the leaf stalk. On the underside of the leaf the veins stand out, forming a pattern of fine ridges like a freshly ploughed field. When drops of rain fall on a leaf the ridges cause surface tension to pull the water into a near-perfect sphere.

Water droplets on fallen ginkgo leaves © Roger Butterfield

In bright but oblique autumnal sunshine, each spherical droplet acts as a lens and focuses a tiny spot of light - making it look just like a miniature crystal ball.

I managed to get a picture of this phenomenon but, unfortunately, I didn't have my macro lens with me. Today I went back, properly equipped, to get some close-up shots. Sadly, the results were rather disappointing due to poor light. I think the gardeners must have thought I was crazy, kneeling amongst the fallen leaves with my backside in the air!

Undeterred, I took a handful of leaves home and attempted to re-create the phenomenon under 'studio conditions' (i.e. on the dining table, lit with a torch). The results are not bad, but would be better with stronger illumination.

Water droplets on ginkgo leaves (in the 'studio') © Roger Butterfield

By the way, there's a blog which is entirely devoted to celebrating ginkgo.

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Comments

Great photos!

More about the Ginkgo on my forum-blog
http://ginkgopages.blogspot.com/

and homepage The Ginkgo Pages:
http://www.xs4all.nl/~kwanten/

Cheers!

Wonderful. Roger thanks for such a fascinating post

A great post, AND, shows my two favorite properties of water: that it is both cohesive and adhesive. Thanks! :-)

Love the pictures, especially the third one. May I feature it?

Lovely photos.

Loved the history, and the pictures and information about water. I've always loved the leaves of ginkgo...so unique.

Thanks all for your positive and encouraging comments.

Kelly: Please feel free to feature the picture.

Dear Roger,

Your ginkgo shots are really inspiring. I'm planning a website and am wondering whether you'd consider granting me permission to use one or two of the pictures. Thanks very much. Sadie

Hi Sadie,

Please email me with details of the images you'd like to use.

Roger

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