Early botanical illustrators, she explains, "were doing it more for the purpose of scientific documentation than art." The people who created cave paintings, on the other hand, were probably shamans trying to perform sympathetic magic, depicting images from a hunt, for example, to ensure the hunt's success and to consecrate the life of the animal that would die. Nessler stops short of comparing herself directly to a shaman, but she works with a sense of mission, going beyond capturing the appearances of her flowers to celebrating their essences and strengthening our primal links to them.

She often portrays the same flower in bud, full bloom, and death, all in the same painting, because, as she says, "I'm trying to capture the sense of the plant, its whole life cycle. If I can do this well enough or right enough, someone who knows that plant will understand something that they didn't before, something that can't be described with words, that's just there."

Nessler works on vellum, as did classic botanical illustrators, but where they preferred smooth, light-colored skins, she tends to use darker surfaces that are more textured, more expressive, and more like cave walls. "They're harder to use because sometimes the vellum will dictate the specimen that can be painted on it, but when the two work together, the end result has another dimension, more depth," she says. "In the way that cave paintings disappear into the rock, I want my work to look as though it's merging with the vellum and emerging from it, so you don't know whether it's coming or going."

Nessler always starts with a live specimen, often from her own land, though she sometimes has whole plants shipped overnight to her. "If I can't get a specimen, I don't do the flower," she says. "Once or twice, I tried working from photographs, but that's second-generation color, and it's important to touch the thing I'm painting, to know the physical sensation of it, not just with my eyes but with my body. How is it graceful? Is it rigid or flexible? It's simple kinesthesis. I want to understand the form by experiencing it."

Once she's chosen her specimen, she sketches it onto tissue. After moving the tissue across the vellum to find the perfect placement, Nessler creates a detailed drawing. Next, she washes in the base color and finishes with translucent watercolor and touches of opaque white body paint. Using the tip of a small brush allows "absolute control to build the color until I get the depth I'm looking for," she says.

The result, says Susan Frei Nathan, whose gallery represents Nessler and sells her pieces starting at about $1,600, is the work of a master botanical artist. "She has captured the essence of the botanical in a very romantic way. She evokes its feeling, capturing its luminosity through the use of vellum. They're very personal pieces," Nathan says. With, perhaps, a little bit of magic in them.