For Science

Recently I engaged in actual real live science.

You may remember a few weeks ago, I stumbled upon a new-to-me-species, dwarf nettle (Urtica urens).

That’s what the Seek app said it was, anyway. Of course, I did my own research as well, but aside from height I really didn’t know how to tell the difference between U. urens and its taller sibling, U. dioica, the stinging nettle that most of us know and love. The leaves are supposedly different, but I couldn’t really tell for sure. Oh, and the sting is worse. But I’m not one for wandering unprotected through nettle patches to assess how bad the sting is!

But I digress. My first step in researching a new plant is usually to check the Maryland Biodiversity Project website to learn what other sightings they report for this particular specimen. Their listing for dwarf nettle puzzled me: excluded, it said. No records in Maryland. No sightings at all.

So, I did what any enthusiastic plant person would do. I reached out about my possible sighting. Here was my chance to forward our understanding of local Maryland biodiversity!

How could it not be dwarf nettle? The other patches of nettles have already grown to between two and two and a half feet, towering over surrounding plants. The “dwarf” patch still stood at a diminutive height of 12 inches tall, max.

Stinging nettles already taller than the surrounding plants
Stinging nettles already taller than the surrounding plants

But it’s not just about height after all. Here is the biggest difference between the two varieties: stinging nettles are perennial whereas dwarf nettles are annuals. The former spread via horizontal rhizomes. The latter sport taproots.

Which meant digging up specimens. I donned my thickest gloves and heaviest shirt sleeves and headed out in the rain with a trowel. For science.

I gingerly excavated two separate plants with the same results.

Stinging nettles spread via rhizomes
Stinging nettles spread via rhizomes

Rhizomes. Without any other evidence at all – apparently something about the flowers and seeds are different too – we now know conclusively this patch of nettles is indeed U. dioica, regular ol’ stinging nettle.

This is why we don’t use only apps to identify wild plants. Or even apps + websites (like this one). And it helps to know as much as possible about botany, plant life cycles, and the timing and distribution of local species.

(I’m still puzzled as to why this particular nettle patch has such stunted growth, but that’s science for a different day!)

3 comments

  1. Looking at your original post the nettle appears to be growing beneath a black walnut tree… Could the allelopathic properties of black walnut have some effect on the plant size?

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