While the rest of us were still walking along the edge of the lake, Jakob scrambled down from some wooded bank (this was a common occurrence by now) with a leaf of the mystery plant. The group passed it around and exchanged glances -some seemed to know by smell that this plant was “the plant,” others were content to recognized it as a Dryopteris – and we set off to see the plant in situ. Once we entered the woods, Jakob and the other local Dryopteris experts started to sort through the dozens of ferns around us: dilatata, dilatata, another dilatata, mystery plant, another dilatata. As with the Dryopteris affinis aggregate, the differences were small but real. The mystery diploid plant differed from the more abundant Dryopteris dilatata in leaf color and texture as well as something about the presentation of the leaves (flow cytometry would later confirm our field determinations). We spent about an hour looking at the plants and making a few collections, forming a rather comical human chain to pass collection bags and leaf samples up and down the slope. In the background, a well-caffeinated Jens scampered about, identifying every Dryopteris on the mountain. We took some photos and headed back down to the lake for some lunch.
After lunch, we walked to the other side of the lake to look for Botrychium in some pastures but were unable to find them – we surmised that the ephemeral plants had either died-back for the season or they were all eaten by cows, which apparently is a thing that happens in Switzerland. Our consolation prizes were Gymnocarpium robertianum, Dryopteris borreri (which I am proud to say I picked out from a distance of twenty feet), and Asplenium septentrionale, a peculiar spleenwort that looks like a tuft of grass. On the way back to the parking lot, we spotted a large population of Selaginella selaginoides atop a rock wall; we made a few collections (every herbarium needs more lycophytes!) and then headed back to the cars. We were headed for the town of Härkingen some two hours to the north, but made another stop halfway to see Asplenium scolopendrium, Polystichum setiferum, and an undescribed member of the Dryopteris affinis complex.