The King Penguin series of books began publication in 1939 and continued through 76 titles until 1959. These slim volumes covered a remarkably wide range of subjects, ranging from ballet to ballooning and from cricket to the crown jewels. You can read more about them here.
Number 57, published in 1950, was A Book of Mosses by Paul Richards.
King Penguins were noted for their beautifully designed covers and this title carried a pattern of stylised moss plants.
In addition to the well written text, this volume contained exquisite illustrations taken from Johannes Hedwig's Descriptio et adumbriato microscopico-analytica muscorum frondosorum, published between 1787 and 1797.
Hedwig's book contained ground-breaking researches on the structure of mosses, using the best microscopes that were available in the late 18th. century. In his day the details of the reproduction and life cycle of mosses was unknown, but his observations led him to speculate, accurately, that mosses carried male antheridia and female archegonia that were analogous to the pollen and ovules of higher plants.
Hedwig was a very acute observer and skilled artist. The plate above shows his observations on the peristome arrangements of moss capsules, Atrichum undulatum (top left); Grimmia apocarpa (bottom right); Tortula rigida (top right); Camptothecium sericeum (centre left); Fontinalis squamosa (bottom left)
Here is Rhacomitrium lanuginosum and ........
.... here's Camptothecium sericeum.
King Penguins cost one shilling each when they were first published and were very popular, so most titles aren't hard to find in second hand bookshops. Many of them cover natural history themes.
You can read an on-line version of Hedwig's original book by clicking here The text is in Latin. The illustrations are astonishingly good, especially when you zoom in on the detail.