Nineteenth-century German illustrations of pollen “in extreme magnification” have recently entered the public domain.

So reports the Public Domain Review, an online journal and not-for-profit project whose organizers keep their eyes peeled for material that is no longer protected by copyright.

The illustrations, one page of which is on the left, appeared in Ueber den Pollen (1837), a book by St. Petersburg-based German pharmacist, chemist and botanist Carl Julius Fritzsche (1808-1871).

Identifications of the pollen spores can be found in the online copy of the book – which is in German.

In their recent post of the pollen pages, the editors of the Public Domain Review also posted a scanning electron micrograph from the Dartmouth Electron Microscope Facility at Dartmouth College (released into the public domain by Dartmouth) showing pollen at similar magnifications to those shown in Fritzsche’s book – around 500 times magnification.

The Dartmouth SEM includes pollen from a variety of common plants including sunflower, morning glory, hollyhock, lily, primrose and castor bean.~TM