E. maculatum?

We aren't supposed to get E. maculatum in Arkansas. Plus, that plant would have leaves with petioles; but the one in the photo has perfoliate leaves. Since nobody else answered, I'm guessing that the plant is a freak. I'll just chalk it up as another mystery. Thanks for the feedback jaynine.

I was curious, so looked further and found an exerpt from An Illustrated Flora of the Northern United States, Canada and the British Possessions. Vol. 3:

"16. Eupatorium perfoliatum L. Common Thoroughwort. Boneset. Indian Sage. Fig. 4167.

E, perfoliatum L. Sp. PI. 838. 1753. Eupatorium truncalum Muhl.; Willd. Sp.

PI. 3: 1751. 1804. Eupatorium perfoliatum truncatum A. Gray,

Syn. Fl. 1 : Part 2, 99. 1804.

Pubescent, stout, branched above, 2��-5�� high. Leaves opposite, or rarely in 3's, connate-perfoliate, or the upper, rarely all, truncate and separated at the base, divaricate, lanceolate, long-acuminate with a slender apex, finely crcnate-serrate, rugose and pubescent beneath, 4-8' long, 1 '�� 1 ��' wide; heads crowded, 10-16flowered, ��"-��" high; involucre campanulate, its bracts lanceolate, acutish, in 2 or 3 series, pubescent, the outer shorter; flowers white, rarely blue."

Seems you've found a rarity!

Thanks for the follow-up jaynine. I think you're right and appreciate the info. Sorry I'm so delayed in my response.

Just yesterday I found a single perfectly triperfoliate example of Eupatorium perfoliatum in a small, often quite wet, cleared area near Cub Run in Centreville VA with a total of about 20 of the common biperfoliate specimens. Unfortunately the plants are starting to dry up this late in the season and it was not a very good specimen---but it was clearly triperfoliate. By the way, Cub Run is a major tributary of Bull Run, famous for the two Civil War battles fought near it. Even Eupatorium perfoliatum seems to be rare in this area, but Eupatoruim serotinum is very common.

Another reference to this rare variety is found in The Ottawa Naturalist, Vol. XXX, No. 11, Feb. 1917, p. 142 (online Google Book) in an article Notes on Some Ottawa District Plants by W. Hague Harrington: "Eupatorium perfoliatum L. Thoroughwort. Boneset. Examples of this common boneset were found August 7, 1905, growing along a ditch at Kirk's Ferry, with whorls of three connate perfoliate leaves in place of the usual two opposite ones. The extra leaf adds much to the symmetry and beauty of the specimens. Other examples of the same triperfoliate form have since been observed on several occasions in swampy ground nearer Chelsea."

Seen a lot of boneset and the plant certainly does have the boneset look to it. As an aside, around here multiple Eupatorium species (or whatever they have been renamed to) grow side-by-side. See one and there are probably others in that clan in close proximity.

FataMorgana

Surprised that old post popped back up. I've since seen other Eupatorium examples with leaves in whorls of three, including both E. perfoliatum and E. rotundifolium. They are, in my opinion, more handsome plants than the normal ones, because of that nice symmetry. I also found the phenomenon, once, in Eupatorium X cordigerum, which is a hybrid between E. perfoliatum and E. rotundifolium.