Out for a run with my son and this plant brushed up against his knee. Within seconds it made small red spots and within minutes the spots turned to small bumps.
What plant is this, and more importantly is it poisonous? Any advice?
We live in Minnesota and it's currently September.
Yes, it is a stinging nettle, they can cause itchy rashes and general irritaion but should subside within 24 hours.
They are actually eaten after being cooked some places, and are widely used to treat a variety of ailments as an herbal medicine, such as hay fever and osteoarthritis.
The leaves and young stems of this herbaceous plant are fitted with stinging hairs tipped with formic acid and other irritants. If touched, these needle-like hairs inject the stinging acid into the skin, triggering a burning, tingling sensation and an itchy rash. Thankfully the symptoms usually do not persist longer than 24 hours. Interestingly, the cooked plant is safe to eat and is popular is some places as a vegetable.
They are irritating but nothing to be too concerned with assuming there is no abnormal reaction or allergy.
More information on the plant and its varieties can be seen here: Urtica Dioica information
Stinging nettle. It's so common on almost any open patch of ground in the more temperate parts of Europe that it seems weird to see this question: I'd expect every child here to have frequent encounters with them.
Their leaves sting and inject formic acid, and the bristles on the stems are quite more thorough with the same. Brushing against them tends to deliver warning bumps (more white than red though) that wear off in about an hour. Falling into them tends to trigger the nastier bristles on the stems, usually good for several hours.
The stinging and burning action is quite basic chemistry, so I don't think that the reactions between people with allergies and others will significantly differ. Skin toughness may make a difference.
The principal remedy is stoicism and ignoring the burn until it subsides.
As others have already mentioned, it's a stinging nettle.
The hairs that deliver the sting into your skin are actually not very strong, and they mostly reside on the underside of the leaves. There's a saying "if you grasp the nettle firmly, it will not sting you", and this comes from the fact that if you choose to harvest a nettle, by grasping it in a smooth motion to use the topside of the leaves to protect you as you grip the stem to pull up the plant, you can avoid being stung.
There's herbal extracts you can get that include nettle, I've also consumed it in a tea (and it had quite a unique, yet pleasant taste). I have heard of it being used as a flavour ingredient in soup also.
The stings do indeed ease after about a day, but they can be quite painful and one can cause more pain overall by scratching them as they are intensely itchy. In my personal experience, once stung, it is important to ensure that you've removed all the stinging hairs from yourself and your clothes or they will continue to sting. As a child I was always advised to apply wet mud to the stings and let it dry in order to ease the pain and itching - it did seem to work.
