Birch-city Umeå – home of Flora-L Design
Umeå in the North of Sweden is the home of Flora-L. This university city of a bit more than 100 000 inhabitants is also known as the city of birches. As plant biologists, we have a special appreciation for the birches (Betula) of Umeå. With this microscopy pattern we want to celebrate the tree of Flora-L’s home town.
The birch tree has been a symbol of Umeå since 1888. After a great fire destroyed most of Umeå, the city was redesigned to include birch trees planted along the streets.
Cork cells protect the tree
For generating this festive pattern, we observed a section of a birch branch under the microscope. This microscopy image shows the outermost layers of this woody tissue. You can see cork (or bark) cells closest to the top of the image. They are the skinny, flattened cells arranged in organized rows. These cells are usually filled with air and have special protective compounds in their cell walls. The compounds are usually lipid based, which means they are hydrophobic (repel water) .
This special layer of cork cells plays a protective function for the tree. It helps the stem or branch to conserve and maintain water balance and protects it from attacks from insects and herbivores. The cells in such a slices from the tree are usually not blue. Here they were dyed with a stain so that it is easier to see them and to distinguish different tissues.

A pattern with a special feature
We have shown you many patterns where the cell walls are stained darkly and the interior of the cells are clear. Our birch bark pattern here is unique: the cell walls in bark are hydrophobic and actually repel the stain, making the walls stay white. This makes the whole pattern look reversed compared to the way cells usually stain. This phenomenon gives the pattern a very light and airy feeling.
You can find this fascinating pattern as convertible bag in our webshop. It was also released today in our Society6 print on demand shop on a large variety of products, as well as on Spoonflower as fabric in various qualities, wallpaper or ready made textile products.
