dsc04936Scrolls are widely used as part of bonsai displays. At some exhibitions they are not allowed, and that includes the big Japanese Kokufu-ten  and in Europe well known Noelanders exhibition. Of course this means that some type of displays are limited or not possible to set up.
The scroll is used to extend the impression of time and place of the scenery that the display is showing. In a more or less implied way. Specially at the shohin style Toko-kazari display the scroll is always used.The motives of the drawing or painting will almost always be aimed at nature. In a private Tokonoma display that is more personal other themes of a more philosophic character may be shown.

The main role of the scroll is to elongate the impression of nature, underlining a certain feeling and even with a philosophic approach. It can be reflected by calligraphy, a bird flying i.e. but newer repeating what`s in the Tokonoma display. Do not use a painting/scroll showing branches of a tree, when branches are already presented by the bonsai. Use such a picture with a Suiseki instead. Also flowers at the scroll painting is not used when setting up a flowering bonsai, because it is a repetition of the theme.

 

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Hako-kazari shohin display. Scrolls are never used in this type of display. Display from Caroline Scott, UK at the first British Shohin Association exhibition.
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Kokufu-ten in Japan. At this specific exhibition scrolls are not allowed but are used in many other exhibitions in Japan.
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The Toko-kazari shohin display with two shohin-bonsai and one accent planting always make use of the scroll painting. Mame-bonsai display by Morten Albek.