These fabulous botanical microanatomy plates constitute the total of illustrations present in 'Anatomia Vegetal' by Frederik Elfving (1929) and published by FE Wachsmuth (Leipzig) which is online at La Biblioteca Virtual de Patrimonio Bibliográfico from the Spanish Ministry of Culture.
Elfving (1854-1942) was a professor of botany at the University of Helsinki. There are a couple of books at the Internet Archive about a voyage to North America to which he contributed.
Apparently there is descriptive text to accompany the illustration plates but it doesn't appear to have been digitised.
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