Our Mystery Plant is a Mountain Mint.

https://garden.org/plants/view/78608/Narrowleaf-Mountain-Mint-Pycnanthemum-tenuifolium/This plant attracted my attention when I saw our honey bees heavily foraging in it. We are in a wildflower transition period where the blossoms on the Sweet Clover and Canadian Thistle are waning and the Golden Rod is just beginning to open. It seems the bees are foraging mostly on white clover which we have much of but we were happy to find something else that they loved.

My husband and I searched all of our plant reference books and several online data bases and were unable to identify this plant. The plant had grown up in an area where we had planted a wild flower seed mix several years ago. So I decided to go to what I assumed was the source. The wild flower seed mix we planted was from American Meadows https://www.americanmeadows.com/wildflower-seeds . We first search their website and were unable to find any plant that resembled our mystery plant. I then decided to contact the company. I used the contact form on their website and included a picture of the plant I was trying to I.D. This was on Sunday. I received an automated reply that day saying they received my message and would try to respond within 48 hours.

My husband and I continued to search online wildflower data bases to no avail and on Monday I received an email from Lisa at American Meadows. She thought the plant in the photo was Yarrow. I replied immediately. At first glance the plant may look like Yarrow, but we also have Yarrow growing on the farm and there are several differences in the two plants. The flowers are different, but more noticeable is the difference in the leaf structure and I have never seen the bees visit Yarrow.

I sent Lisa a second photo of our mystery plant which showed the leaves more clearly. Lisa replied that same day. From this picture she could now see that the plant was not Yarrow. She could not identify the plant but if I could send a close up of the flowers she would “call in the troops” to help find our answer. On Wednesday I sent a couple more photos, described the light scent of the flowers and told her we lived in South-East Michigan.

Later that day I was surprised and excited to receive Lisa’s email. It read: “Success!

The plant is Mountain Mint, probably Pycnanthemum virginianum, which is the common species in Michigan. There is a related species that is much less common, called Pycnanthemum tenuifolium. The main difference is that P. virginianum has pubescent stems, whereas the stems of P. tenuifolium are glabrous (i.e., not hairy). I can’t see the stems well enough on your photos to tell whether the stems are pubescent or not.”

Lisa said her source of this information was a botanist here in Michigan.

I did an internet search and found photos of Mountain Mint and discovered that it was indeed what we had. I at first believed it was Pycnanthemum virginianum, the more common species. On Thursday after I read Lisa’s message a second time I began to question that. I didn’t remember this plant having hairy stems. On my next trip to the farm I confirmed this. The stems of our Mountain Mint are smooth. We have the less common of the two, Pycnanthemum tenuifolium. Common names for this plant are Narrow-leaved Mountain Mint,  Common Horsemint, and Slender Mountain Mint. My husband and I could not be more thrilled than to have this mystery solved. We will encourage this plant to spread and perhaps even propagate it.

This might go without saying but in a day and age where good customer service is hard to find I have to say that we greatly appreciate the help that we received from Lisa at American Meadows. She certainly could have determined that our plant was not something that came in the seeds we received from them an left us on our own. Instead she went the extra mile to help us solve the mystery. At this time we do not have a need to purchase wild flower seed but if we ever do we will return to American Meadows and perhaps if you decided to purchase wild flower seed you will consider them as well.