  Two mathematical aspects of the centuries-old Japanese sashiko stitching form
hitomezashi are discussed: the encoding of designs using words from a binary
alphabet, and duality. Traditional hitomezashi designs are analysed using these
two ideas. Self-dual hitomezashi designs related to Fibonacci snowflakes, which
we term Pell persimmon polyomino patterns, are proposed. Both these designs and
the binary words used to generate them appear to be new to their respective
literatures.
