Via Wikipedia, this great illustration of “Lichenes,” drawn by Ernst Haeckel to emphasize his ideas of symmetry in his Artforms of Nature, published in 1904. Click to enlarge.

Haeckel’s stylized drawings convey these lichens in their most basic forms, with much of their random meandering growth reduced to precision, as evidenced in the strict circles of #8 and #9, the ovals of #10 and #11. Despite the fact that, in the field, these are apt to appear far less uniform in shape, Haeckel has captured the “personality,” if you will, of each species, making them reasonably recognizable.

Just for fun, in the key below, we’ve linked some of the species names to a current photo from other websites for comparison. Links open in a new window; use your browser’s back button to return here.

Here’s the key to these drawings, by number, with some synonymy of a more recent day added, apparently by the annotator for Wikipedia.
1. Cladonia retipora (Floerke) = Cladia retipora (Labill.) Nyl. (an Australian species, but here’s a photo from Pinterest)
2. Cladonia perfoliata (Hooker) = Cladonia perfoliata
3. Cladonia verticillata (Achard) = Cladonia cervicornis ssp. verticillata (Hoffm.) Ahti
4. Cladonia squamosa (Hoffmann) = Cladonia squamosa (Scop.) Hoffm.
5. Cladonia fimbriata (Fries) = Cladonia fimbriata (L.) Fr.
6. Cladonia cornucopiae (Fries) = Cladoniaceae sp.?
7. Sticta pulmonaria (Achard) = Lobaria pulmonaria (L.) Hoffm.
8. Parmelia stellaris (Fries) (non (L.) Ach.: preoccupied) = Physcia stellaris or Physcia aipolia (Ehrh. ex Humb.) Fürnr.
9. Parmelia olivacea (Achard) = Melanohalea olivacea (L.) Essl.
10. Parmelia caperata (Achard) = Flavoparmelia caperata (L.) Hale
11. Hagenia crinalis (Schleicher) = Anaptychia crinalis (Schleich.) Vězda

If you appreciate the elegance of nature, as Haeckel clearly did, you should look at this entire book. Browsing through the illustrations was like an instant review of invertebrate zoology and paleontology courses from college. Many of his drawings feature protozoans, medusoids, and other familiar lifeforms in those textbooks (if not in life); these would have enhanced some of those courses! Explore more at:

Kunstformen der Natur, Haeckel, Ernst, 1834-1919, Bibliographisches Institut Leipzig. Contributed to Biodiversity Heritage Library by University of Illinois Urbana Champaign.