A while ago I received a pack of seeds described as Pycnanthemum Pilosum / Mountain mint. The seeds are small (below 1 millimeter) and brown:


Plants grown out of these seeds are around 40 centimeters high and spread widely. Leaves are bright green and smooth, around 3 - 4 centimeters long:


with strong minty smell (though quite distinct from let's say Mentha × rotundifolia or Mentha spicata).

Stems are square, with very short hairs.stem

Recently plants started to flower:




producing clusters (around 1.5 cm in diameter) of small (3 - 4mm long), slightly flowers along the stem. Flowers are white, with light shade of purple. with no spots or other marks.

The plant started to flower in the first year after sowing (the plant is around 4 months old, planted outside, in Central Europe).

The plant doesn't really resemble Pycnanthemum pilosum descriptions I found online (for example this or this), which, among other differences, describe long and narrow leaves.

I wonder if someone can help me identify it. Thanks in advance.

  • $\begingroup$ I guess I'd like to know which characters don't seem to match. $\endgroup$ Jul 4, 2019 at 18:04
  • $\begingroup$ @BryanHanson Not sure if I get your comment. Could you elaborate? Thanks in advance. $\endgroup$
    – user52435
    Jul 8, 2019 at 17:38
  • $\begingroup$ Your edit helped. So, chief discrepancies are the leaves are too broad, and, it's not hairy. I looked up some pictures a colleague of mine took here in Indiana, which we ID'd as P. pilosum and it's definitely not your plant. Given the similarities of many mints I think one has to start fresh and attempt an identification. $\endgroup$ Jul 8, 2019 at 17:48
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    $\begingroup$ Can you say more about the flowers? Size? Color? Spots? In the one pic they look pretty pale off-white. Any odor to crushed leaves? $\endgroup$ Jul 8, 2019 at 17:52
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    $\begingroup$ That's where I was headed if you answered with minty smell. Will revise my answer for posterity. $\endgroup$ Jul 8, 2019 at 19:49

1 Answer 1


I'm going to take a stab at this. If your plant is not particularly aromatic, I feel pretty confident it is Lycopus uniflorus. There are good descriptions here and here. In particular, the description of the flowers at the Minnesota site, as having 2 purple-stemmed exserted stamens seems to match your flowers. Apparently this species should have a tuber (should you end up digging yours up), while Lycopus virginicus which is probably a good second guess does not have tubers (see the differential description at the bottom of the Minnesota page).

Updated and Revised Answer

With additional pictures of now more mature flowers, which are clearly lilac in color, and the info that the leaves are strongly minty smelling, we'll revise the answer to Mentha arvensis, which fits all the available info. More here.


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