In search of Hexastylis minor [Asarum minus] or Little Heartleaf in South Carolina — 2018-03-24

For those of a sensitive nature, please be aware that I’m immediately jumping in to the brambles of some very geeky botanical stuff here. Disclaimer: Much of the following few paragraphs is my editorializing about taxonomy and such, so if you just want to look at the eye candy (pretty pictures), then skip ahead — my feelings won’t be hurt even one bit, but you do get extra points if you make it through the weeds.

There has been a move about to place the North American Heartleafs in the genus, Asarum. Currently, they are known by most botanists to be in the genus, Hexastylis. Taxonomy is the way that humans, according to their nature, order things so that they can better understand the world around themselves. The taxonomic way of classifying organisms is based on similarities between different organisms. A biologist named Carolus Linnaeus started this naming system; he also chose to use Latin words. Taxonomy used to be called Systematics.

The North American Heartleaf is ordered by discrete levels:

“Older” Taxonomy:

Kingdom: Plantae
Clade: Angiosperms
Clade: Magnoliids
Order: Piperales
Family: Aristolochiaceae
Genus: Hexastylis

or

“Newer” Taxonomy:

Kingdom: Plantae
Clade: Angiosperms
Clade: Magnoliids
Order: Piperales
Family: Aristolochiaceae
Subfamily: Asaroideae
Genus: Asarum
Subgenus: Heterotropa
Section: Hexastylis

From a fairly recent paper by Brandon T. Sinn, called, Asarum chueyi (Aristolochiaceae), a new species from the foothills of the Blue Ridge Mountains of Tennessee and Virginia, USA, the following was written: “…the North American members of Asarum do not form a monophyletic group, but instead comprise two separate monophyletic groups. North American Asarum species with separate sepals, two deciduous leaves per node, and flowers that are autonomously self-pollinated via delayed stamen movement are found on both the east and west coasts, and form a clade that falls within Asarum subgenus Asarum. North American taxa that produce a single evergreen leaf per node and herkogamous flowers with connate sepals are restricted to the eastern portion of the continent and have been placed within Asarum subgenus Heterotropa (Kelly, 1997; 1998) section Hexastylis (Araki, 1937). Species of subgenus Heterotropa have showy, complex calyces that may mimic the sporocarps of basidiomycete fungi (Vogel, 1978; Lu, 1982; Sugawara, 1988; Leins and Erbar, 2010) and appear to have influenced the diversification of this subgenus (Sinn et al., 2015b). The North American members of this subgenus remained under-collected and under-described, most obviously due to their often restricted ranges, low growth habit, early flowering period, and the difficulty of working with the deformed flowers of pressed material (Ashe, 1897; Weakley, 2012).”

So…… I remain in the group of botanists/naturalists who have not bitten the taxonometric bullet and switched over from Hexastylis to Asarum. As Robin Sharma said, “Change is Hard at the Beginning, Messy in the Middle, and Gorgeous at the End.” Right now, I think that I am in the middle…

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Now, let’s get to the results of the field trip. Here is a typical example of Little Heartleaf with its 11 flowers tightly packed near the ground at the center of the plant:

Little Heartleaf Little Heartleaf

We arrived at the site, having been given good directions by my botanist friend, Chick Gaddy. If anyone in the state knows Heartleaf, it is he! Thank you, Chick! On this trip, my botanizing companion was my good friend and photographer, Alan Cressler, from Atlanta, Georgia. Alan had called and asked if I knew where we could photograph Hexastylis minor, and I had to do a bit of research and call around. Neither of us had seen it, even though it is not a rare species at all.

We found a good place to park my truck and then gathered our gear. We walked a short distance to the wooded hill beside the road. It is a fairly open woods with very little understory. Almost immediately, we began to see the leaves of Heartleaf scattered in small groups among the leaf litter. At this point, it was just a matter of finding blooming plants and then selecting the best ones to photograph. Here are a couple of shots of just the leaves of this species:

Little Heartleaf leaves

Little Heartleaf leaves

Notice the heart-shape and significant, light green variegation patterns in the leaves. These evergreen leaves are quite easy to spot in the winter woods. Sometimes, there are only a couple of leaves growing from a particular plant. Other times, there can be up to a dozen or so leaves, depending on the age of the plant. Not surprisingly, the plants with more leaves will produce more flowers. We were excited to find many blooming plants. Here are some images of those plants. Notice the wide variety of markings on the flowers. This is quite a variable species when it comes to flower color. The odd, urn-shaped flowers are borne just above the surface of the ground and generally go unseen (except to the pollinators, which are probably ants and other small insects) until and unless the leaf litter is gently pulled away:

Little Heartleaf Little Heartleaf

Little Heartleaf

Little Heartleaf

Little Heartleaf

I even found one with greenish spots on the flowers:

Little Heartleaf

Little Heartleaf Little Heartleaf

Little Heartleaf

Little Heartleaf

There are about a dozen Hexastylis species in the eastern U.S., some of them quite rare, but almost any walk in the woods in the Southern Appalachian Mountains will lead you to find one or more of these species. You might ask how the Little Heartleaf differs from some of the other Heartleaf species. From my observations, there is one main characteristic that is fairly easy to spot. It is the shape of the flower. For Little Heartleaf, it is similar to Hexastylis heterophylla or Variable Heartleaf (which it more closely mimics), but the size of the corolla tube is much shorter for Little Heartleaf. Its corolla opening is as wide or wider than the depth of the corolla tube. Here are a couple of shots that will give a pretty good comparison of the flowers of both species. First, Hexastylis heterophylla:

Hexastylis heterophylla

Next, Hexastylis minor:

Hexastylis minor

Note the bulge in the corolla tube just below the flower opening. Also note that H. heterophylla shows white at the outside base of the flower and to the pedicel which connects the flower to the growth center of the plant. H. minor is uniformly colored.

Some descriptions state that the leaves of H. minor are more strongly variegated than in the other species, but I’ve seen H. heterophylla leaves that look quite the same as those of H. minor. So I would not use that as an exclusive determining characteristic.

We did find a few other wildflower species in bloom at this site. One of those is Trillium cuneatum or Little Sweet Betsy. It was scattered lower on the north-facing portion of the hillside near a small creek. Here are some shots of these flowers:

Little Sweet Betsy Little Sweet Betsy

Little Sweet Betsy

There were also a numerous winter leaves of the summer-blooming orchid, Tipularia discolor or Crane-fly orchid nearby looking a bit worse for wear. This is a common, terrestrial orchid, and it can be found on almost any rich, wooded hillside in the upstate of South Carolina:

Crane-fly orchid leaves

It was a great trip, and it was only an hour or so from home. That’s always a good thing. Again, I really appreciate the location information that Chick gave us. Often times, directions are rather vague, and one spends a lot of time looking around for the exact place to find the species. That was definitely not the case for us.

Alan and I headed to another couple of sites after we left the Little Heartleaf site but, to me, this was the highlight of the day. It’s very satisfying to go out into the field and discover wonderful wildflower species to photograph — especially one that is new to the photographer. The weather was overcast (good for photography) and the rain held out until we got back to Greenville. Could not ask for more.

Stay tuned for further wildflower reports. Even though winter seems not to want to release its hold on the season, Spring is knocking on the door…

–Jim

3 comments


  • Ryan

    Breathtaking!

    March 26, 2018
  • sonnia hill

    I read and enjoyed your “very geeky botanical stuff”. I will give myself extra blog points for that.

    I have a question. What are the stems, petioles, pedicels visible all around the flowers of the Hexastylis minor? I will do some research on this very fascinating species. Messy in the Middle is a good place to be until accepting the new.

    April 07, 2018
    • Jim

      Sonnia, what I believe you are referring to are the round, fleshy, leaf pedicels. The are usually around 6 inches (13.5 cm) long. The flowers all rise from the center growth point in the year after the leaves (that you see) are produced. Some Hexastylis species produce more leaves per plant than do others. After anthesis, the plant will produce a new set of leaves.

      April 07, 2018

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