Much ado about Memminger’s Heartleaf Wild Ginger

This spring, we flowered the highly confused NC native wild ginger, mistakenly known as Asarum memmingeri in the garden. In reality, it’s never been given a proper name, so we refer to it as Asarum sp. nov. Allegheny Wild Ginger. Below, Patrick explains how this ginger was dropped into a botanical abyss, and what needs to be done to return it to proper recognition, and to correct a cascade of past taxonomic errors. -ta

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When I was a boy the tiny-flowered evergreen wild gingers that grew all over our land in Alleghany County, North Carolina seemed like they must be a common species, and should have a name. As a boy of 12, however, I had a hard time placing a name on them since they didn’t seem to fit the photographs in popular wildflower books or match the plants that my grandmother’s flora called Hexastylis virgnica (now Asarum virginicum).

I became obsessed with heartleafs as a child and the curiosity remains strong. When I entered college I was lucky enough to take Dr. Peet’s Ecological Plant Geography class at the University of North Carolina, Chapel Hill. Our class, which was all graduate students and me (as a sophomore), was expected to do a project detailing and explaining the range of a particular genus or family of plants. I chose the smooth-leaved evergreen Asarum, then known then as Hexastylis.

I spent the spring semester travelling to every corner of the American South seeking species I didn’t know and trying to fill in the vacant counties in the range maps of those species that I did know. I took countless measurements of calyces and made copious notes on habitat. I was shocked when I travelled to southeastern Virginia to visit the area where Asarum virginicum was likely first collected. These true Asarum virginicum plants were nothing like the “A. virginicum” I was so used to seeing in my boyhood home.

A quick trip to the Earl Core Herbarium at West Virginia University, and later to the Smithsonian, brought to light a serious problem with what botanical taxonomists currently refer to as Asarum virginicum and an even larger problem with what we call Asarum (Hexastylis) rhombiformis and Asarum (Hexastylis) memmingeri.

It seemed as if the Alleghany County plants I had called Asarum virginicum as a child had been mistakenly identified by WVU taxonomist Earl Core as Asarum memmingeri. Complicating this further was that the probable original type specimen for A. memmingeri would later be published under a new name, H. rhombiformis!

To make sense of the cascade of errors, we need to go back further in time. This story begins in 1897 with W.W. Ashe’s publication of The glabrous-leaved species of Asarum of the southern United States in the Journal of the Elisha Mitchell Scientific Society. Here, Ashe describes for the first time Memminger’s Heartleaf (A. memmingeri). From the description it is obvious that he is describing a plant with a very small flower with a very narrow opening (7 mm wide or less).

Error #1 occurred when Ashe described the original type locality as Mitchell County, based on a collection by E.R. Memminger. When I was looking for a type specimen, the best option I could find was a specimen collected (in duplicate) by E.R. Memminger himself that he says in his own handwriting represents the type location. During Ashe’s time, it was not required to designate a type specimen, but the problem was that Ashe’s citation of Memminger’s specimen was actually from Henderson County (“Tranquility”, Flat Rock, NC), not Mitchell County.

Type specimen of Asarum memmingeri collected by E.R. Memminger

Error #2 occurred as we fast-forward to 1987, ninety years after Ashe published his work, when L.L. Gaddy described a new species of Hexastylis that occurs in Southwestern NC and Northwestern SC as H. rhombiformis (Asarum rhombiformis (combination not yet made). In this description he cites E.R. Memminger’s specimen from Henderson County, which, is actually the type specimen of Asarum memmingeri as representing his new species H. rhombiformis. Consequently, the name H. rhombiformis is invalid and this plant should be known as A. memmingeri.

Error #3 occurred when J.K. Small of the New York Botanical Garden, Earl Core of West Virginia University and others annotated (attributed) numerous Asarum collections from West Virginia, Virginia, and NC, of an un-named species that they mistakenly identified as A. memmingeri. Blomquist and all modern authors have since combined these tiny-flowered plants with small openings to the calyx tube within a “catch-all” concept of A. virginicum. Other taxonomists since have followed their mistaken identification of A. memmingeri or A. virginicum for these plants that are known to range from WV south to NC.

We know that these plants that J.K. Small, Earl Core, and others called A. memmingeri actually represent the heartleaf from my Alleghany County childhood homestead and surrounding regions that still has no accepted name.

It is time to clear up the confusion and formally describe these plants along with a new, correct scientific name. For our purposes we will refer to them here as Allegheny heartleaf for a common name (in reference to the mountains, which have a different spelling than the NC county, rather than Alleghany County, NC).

In vegetative form, the Allegheny heartleaf is similar to most of its relatives including A. virginicum, minus, heterophylla, and naniflora. They are tightly clumping with leaves that tend to be as wide or wider than long with a broad cordate base. Though I have found populations with some mottling on the leaves, they tend to lack any variegation altogether.

The flowers on the undescribed Alleghany County heartleaf are much smaller in all dimensions and also differ in the tube constriction from both A. virginicum and true A. memmingeri.

The Allegheny heartleaf is found in typical heartleaf habitat: highly acidic, organic duff beneath oaks and pines and often in association with Rhododendron and Kalmia. They are found along the margins of Southern Appalachian fens and small stream swamps as well as along stream banks and on steep rocky slopes and bluffs that are most often north or east-facing.

The natural range of the species seems to be from Watauga/Avery counties North Carolina, north through West Virginia at low to moderate elevations. In North Carolina nearly all populations are located along the New River drainage, though there are outliers along the Yadkin River drainage downstream to Donaha Bluffs in Forsyth County. This taxa is tightly tied to the Appalachian range with outliers into the piedmont in areas with cool microclimates along rivers that originate in the mountains. Between the mountain populations of Allegheny Heartleaf and the coastal Virginia Heartleaf (Asarum virginicum) occurs A. minus, which largely replaces Allegheny Heartleaf in most of the piedmont of North Carolina.

Allegheny Heartleaf was very difficult for me to grow, even in seemingly hospitable microclimates in Clemson, South Carolina. It seemed to survive but only for a short time, gradually declining and producing dwarfed leaves by the 2^nd season and then disappearing by the 3^rd. I am extremely pleased to have this species growing strong, flowering and producing normal sized leaves for its second season here at Juniper Level Botanic Gardens.

What needs to happen is for Hexastylis rhombiformis to have a name correction to Asarum memmingeri, and for the plant widely known as Asarum memmingeri to finally be named for the first time, hopefully with a specific epithet named for the Allegheny Mountains, which incorporate the heart of its range.