False Mermaid

“But nobody knew how to get in touch. You should have told someone where you were. I got married, Nora, had a baby.” Holly’s expression softened. “I shouldn’t scold you. I know you had good reasons for going away. Just want you to know you’ve been sorely missed.” She glanced at Frank. “Why do I get the feeling this isn’t just a social call?”

“Holly, you remember Frank Cordova—”

“Yes, of course. How are you, Detective? It’s a pity we only meet under professional circumstances. I’d ask you in to sit, but it’s a bit cramped in here—let’s go across to the Herbarium.”

Despite its impressive Latin name, the Herbarium was nothing more than a climate-controlled room full of metal cabinets, each containing specimens of pressed plants from Minnesota and all around the world. No one could enter without comprehending just how antiquarian the field of plant biology remained. Color-coded maps of county biological surveys hung on the wall. The images might be computer-generated nowadays, and the ranges of various plants tracked with GPS coordinates, but the data were still collected by human beings traveling on foot, taking samples from fields and forests and ditches. Holly gestured for them to sit at the battered lab table at the center of the room, and sat forward herself, fingers laced together expectantly.

“What we’ve got are samples of plant material from two crime scenes,” Nora said.

Frank held up two evidence envelopes. “We think both samples may have originated from the same site at Hidden Falls Park, but we need to know whether it’s possible to prove that—beyond a reasonable doubt.”

Holly eyed the bulging envelopes. “I’m not going to promise anything, but I can certainly have a look.”

Nora asked, “Do you remember the seeds you identified from my sister’s hair?”

“Sure,” Holly said. “There were lots of different species, as I recall, pretty typical of seepage swamp: black ash and cottonwood, buckthorn, marsh marigold, Virginia creeper, touch-me-not, wood nettle. They’re all pretty common. But there was one unusual find as well, seeds from a plant called false mermaid. It’s only been documented a couple of places in Minnesota, and only outside the Twin Cities. I was sorry we couldn’t pinpoint where the seeds came from—it would have helped your case, I know.”

“We might have another chance,” Nora said. “I remember that name, false mermaid. Something to do with mythology?”

“I’m astonished that you remember,” Holly said. She pointed to a poster on the wall, photographs of a wispy-looking green plant. A corner inset showed a close-up of three wrinkled seeds. “There it is—the Latin name is Floerkea proserpinacoides: The genus, Floerkea, after the famous German botanist Gustav Heinrich Flörke, and the epithet, proserpinacoides, which means ‘like Proserpinaca.’ Proserpinaca is a semiaquatic plant, also called ‘mermaid weed.’ The fellow who named false mermaid thought its leaves bore a strong resemblance to Proserpinaca. As it turns out, they aren’t genetically related, but the name stuck anyway.”

“But that’s the mythological connection,” Nora said.

Holly smiled. “Wow—no flies on you! Proserpina was the daughter of Ceres—”

“Goddess of agriculture.”

“That’s right. When Proserpina was carried off by Pluto, god of the underworld, her mother spent ages searching for her. When she was found, Ceres interceded with Jupiter, who said Proserpina could return to earth, as long as she’d taken no food or drink during her stay in the underworld.”

Nora felt her memory trickling back. “But Pluto had offered her a piece of fruit when she arrived, and she had eaten the pulp of a single pomegranate seed.”

Holly threw a wry look at Frank. “And here’s me, imagining myself the lone mythology geek in the room. Jupiter suggested a compromise; Proserpina got to spend half the year above ground with her mother, and half the year in the underworld with her husband-slash-captor. Now, here’s the connection to the plant world: Proserpinaca, as I mentioned, is semiaquatic. That means the lower part grows underwater, the upper part grows in the air. That’s how it ended up with the name mermaid weed. Floerkea, on the other hand, grows in seeps and marshes and other wet places, but it isn’t even semiaquatic, so that’s where the ‘false’ part comes in—sorry, I’m sure all this is way more than you needed to know. Back to the samples. What exactly are you looking for?”

Frank said: “We’re trying to establish a connection between two crime scenes, and what we need are a few hard facts.”

Nora jumped in: “I know you’re involved in population genetics, and I wondered if there’s any way to tell whether any of the leaves or seeds from these two samples came from the same parent plant. I know it’s a lot to ask—”