Note: The color of anthocyanidins, anthocyans, carotinoids, and other light sensitive plant material may depend on PH of the water and of the paper.
[5] Herschel referenced an experiment on October 11, 1839 in a paper published in 1840 at the Philosophical Transactions of the Royal Society of London.
Sir John Herschel presented her findings to the Royal Society, giving her full credit in his 1845 paper.
Image permanence have been brought into question, but this problem seems to be mostly related to choice of flower or plant matter.
Bingham, quoting by Sir John Herschel, recommends Corchorus japonicus flower (japanese Jute) for a "fine yellow colour" that "upon exposure to sunlight, it is in about half an hour rendered quite white".