The Science of Botanical Art


By Dick Rauh  

Originally appeared in The Botanical Artist, Volume 12, Issue 2


We don’t always paint members of the kingdom of Green Plants. Although our primary focus is on flowers and sometimes on the fruits they produce, there are temptations in the area of non-flowering plants. Sometimes, even, the forms of mushrooms and other fungi beguile us. For many years it had been assumed that they were plants. The fact of the cellular structure of their vegetative body, and that they reproduce by spores were the strongest argument for this. However, the cell walls of fungi are largely made up of chitin that is the building block of arthropods, and only rarely contain cellulose that is the structural element in plant cells. Recent molecular studies, and an evolutionary line that comes from a protozoan ancestor have shown they are not related to plants. Therefore these non-photosynthetic organisms have been placed in a Kingdom all their own and appear to be more closely related to animals. Since we are botanical artists and often chose some fungi as subject matter, I won’t tell, if you won’t.

There is no question that the lack of chlorophyll, and thence the ability to produce their own food make fungi different from plants. Many of us might wonder, as we paint a beautiful mushroom just what its life style is. Fungi are either saprophytes, (living on dead organic matter), parasites (living on living organisms- us included) or micorrhizal, which are fungi that live in a mutually beneficial relationship with other plants, usually the rootlets of trees, or nitrogen-fixing herbs such as legumes. The vegetative bodies of fungi are threadlike masses of tissue that exist underground, within the wood of a rotting tree, or in the leaf litter of the forest floor. The length of some of these thalli has been known to stretch for miles. Sometimes when growing in a grassy area it forms a circular colony that extends year after year. This produces a circle of fruiting bodies at the periphery of the colony, the magical appearing ‘fairy ring’. 

This vegetative structure is called a mycelium. Some are made up of a single, many-nucleate cell, others have cross walls that divide the body into segments, although some of these walls are perforated and allow nuclei to migrate between segments. All of this is interesting but doesn’t much affect our painting since we rarely illustrate the mycelia. What we paint, the toadstools and mushrooms, shelf fungus and puffballs are the above ground and visible fruiting bodies, technically known as basidiocarps. 

What might be interesting is fungi digestion. The threads of the thalli exude enzymes externally that digest and liquefy organic matter in the near vicinity of the threads, thus allowing the fungi to absorb its nutrients and minerals through the cell wall. Mushrooms therefore don’t need any apparatus for feeding. They are solely the bearer and distributors of spores; evanescent growths of the mycelium. 

Now may be the time to name some of the parts of fungi that we paint. Realize that there are a number of forms that have little application for us, the slimes, yeasts and jellies that make up a sizable part of the kingdom, but never produce anything that is worth painting, unless you have very special tastes. When we think mushroom, it is a structure with a cap or pileus and a stalk or stipe. Some of these bodies are wrapped in a layer of tissue called a veil when they first appear. As these mushrooms grow the cap breaks through the veil. This leave warts on the surface of the cap, and sometimes a cup-like structure at the base of the stipe. Other veils leave a ring or annulus around the stalk. In all cases note the torn, irregular edges of the veil remaining. The surface of the cap varies from dull and warty to smooth and slimy, depending on the species. They also come in a wide variety of shapes and colors, some with a rounded form, others with a distinct bulge where the cap sits on the stalk. In most cases the range from conical to flat pilea denotes the age of the mushroom, but there are many varieties that never flatten. Some mushrooms distribute their spores by means of gills or lamellae that form the underside of the cap. Be observant about how the gills relate to the stalk. Are they free, attached directly to the stalk or do they have additional tissue that runs down the stalk? All these are important identifying qualities along with the color of the gills themselves. Some mushrooms have no gills, but carry a layer of tissue under the cap with pores; scattered openings to release the spores. Typical of the pored fungi are the boletes. The shelf fungi that are found on the bark of trees usually release their spores through tiny holes in the bottom surface of the fruiting body - although some are gilled. 

There are some less mushroom-like members of the kingdom. Bird’s nests fungi look amazingly like a miniature cup-like nest with a clutch of eggs. Morels and false morels have conical caps that are wrinkled, irregular and often reticulate. Stinkhorns are almost embarrassingly phallic. There are coral forms in yellow and pink that look as if they might well be growing undersea. Earthstars are another variety, with outer layers torn in a star like manner. Chanterelles are vase-like with the stalk widening to reveal the gills and an almost concave cap. 

The appearance of the fruiting bodies of fungi is seasonal and generally short-lived. According to Orson Miller (Mushrooms of North America) a moist spring brings out morels, false morels and cup fungi. There is a rather dry spell from late spring until late summer when Amanitas, Russula and slowly some boletes appear. “A cool spell in August accompanied by showers will often bring out large fruitings of puffballs. This is the main time to spot, and sketch boletes and shelf mushrooms and the ‘shaggy mane’ among others. “If the first cooling trend of the fall season is accompanied by fall rains the largest number of mushrooms of the entire year will appear

Although not plants, mushrooms have been part of the vernacular of botanical artists for a very long time. There are some fungi that can stand the shift to the studio and will pose willingly, if only for a few days. Most are extremely evanescent, and will begin to dry and discolor when picked. This makes field sketching, backed up by photography the most logical of approach.. And if you’re careful, you can always eat the subject matter, after your finished painting them.  

  • Gymnoptus acervatus, colored pencil, © Libby Kyer 2003