Friday, June 17, 2022

Eastern Yampah (Perideridia americana)


Early morning light illuminates the lush understory of a small Pickaway County, Ohio woodlot. A spindly, white-flowered parsley stands front left, and that plant was my target on this day.

It's been a pretty good year thus far for seeing and photographing rare flora. But few plants have been as rare as this one. Eastern Yampah (Perideridia americana) is only known from this one locale, and I counted about 75 plants on my visit last May 30. They occupy a fairly small roughly square area, and that's it. There doesn't appear to be any other Yampah plants in the woods. There must be something special about this one section of the woods.

Brian Riley rediscovered Yampah in Ohio - at this very spot - in 2012 or 2013. There was only one definitive Ohio record prior to this find, by the legendary Pickaway County farmer/botanist Floyd Bartley. Bartley's collection label says "... wet woods, 2 miles SE of Whisler, Salt Creek Twp., June 11, 1950. Riley's find was definitely not a rediscovery of Bartley's find, as the sites are about 15 miles apart.

There is an enigmatic Yampah record, reportedly from "prairies, Madison County" in the 1840's. However, there is no known specimen or other corroborating evidence so that one must be regarded as hypothetical. But as prairies or woodlands associated with prairies are the haunts for Yampah, a Madison County record would make sense.

Like many parsley family (Apiaceae) members, Yampah's flowers are arranged in umbels. While this species might superficially suggest some others, upon inspection there is really no likely source of confusion.

The leaves are highly distinctive. Leaflets are incredibly long and narrow, and there are relatively few leaves on the plant. This character along with habitat and time of year - tail end of May, peak flowering into the first two weeks of June - should remove all doubt.

A Yampah hits its stride. On May 30, the colony was just beginning to flower. The curious common name, by the way, is a derivation of a Native American word for plants in this genus.

And there are more species in the genus Perideridia. Thirteen in all, but the other twelve species are all found in far to the west, and mostly in the southwest U.S. Perideridia americana is the only eastern representative. It is known from only ten Midwestern states, and the Ohio population is the easternmost known. Eastern Yampah appears to be fairly widespread only in Illinois and Missouri, but I suspect that many of their populations have been destroyed due to rampant prairie destruction. The plant is known from only a handful of counties in the other states, and overall Yampah is undoubtedly far rare than it would have been at the time of European settlement.

Hopefully Ohio's small population holds strong for some time to come.

PHOTO NOTES: Normally I am not much for flash when photographing plants. It creates too much of a harsh, flat look for my tastes (I didn't always feel this way but have evolved). But there are times when one can use it for good effect. The shady woodlot with dappled light presented lighting challenges, and I shifted to flash to attempt to even things out a bit. Mostly, though, I was turning the flash power (Canon 600 speedlite) way down to send out a soft fill light, which was already muted by a diffuser. For instance, the first habitat shot was made at f/71, ISO 100, with a very slow shutter speed of 1/5 second. Obviously, I was working off a tripod. The flash made the lone flowering Yampah pop and helped separate it from the background. The final shot of the robust flowering specimen was made at f/13, ISO 200 and 1/200. A bit of toned-down flash helped separate the plant from its background, and partially blackened the backdrop.

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