Photograph by Carsten Peter; private collection of Peter Heilmann

Water Lily
Like snorkels, the mouthlike stomata on water lily leaves point up, where they find the air they need.

Photograph by Birmingham Archives & Heritage, U.K.

Fern
Once, forests were crowned with the waving leaves, or fronds, of ferns. Some modern ferns qualify as trees, but most are smaller plants. Their fronds reach up out of understories—and other realms where living is difficult—to catch some light.

Photograph by British Library

Seaweed
It looks like a plant with its branches reaching out, but this seaweed is in fact a kind of marine alga. Seaweeds evolved independently from plants; the resemblance shows that the streams of evolution often converge.

Photograph by William Henry Fox Talbot, Science & Society Picture Library

Grape
Blood circulates through human veins without leaving the body. Grapevine leaves are open to the universe. Gases diffuse from veins to the leaf surface, where the exchange of water and carbon dioxide takes place.

Photograph by Bonnet, Marcellin, Facies Plantarum, Carcassonne Municipal Library, France

Thistle
Life is not easy for a thistle. It grows low, where the big heads and mouths of cows, sheep, and other grazers bow. It resists with spines. These spines are not foolproof. Sometimes thistles get eaten or, in the case of this specimen, picked.