Uncas Dunes Scientific and Natural Area - Minnesota, USA

[McDonough]

How does the poison of the poison ivy work? I mean, do you get rash or something?

There's lots of info on poison ivy, and its a fascinating topic:
http://en.wikipedia.org/wiki/Toxicodendron_radicans

One thing in that link I'm not about, where it states: "After injury, the sap leaks to the surface of the plant where the urushiol becomes a blackish lacquer after contact with oxygen".  I had always believed that the oil is always there on all parts of the plant, not just from an "injured" or broken leaf or stem... simple touching any undamaged foliage will expose one to the rash if it affects you.  I get poison ivy rashes (small pustules/blisters) very easily, even in late autumn or late winter if handling leafless twigs.

Other highlights:
- Urushiol oil can remain active for several years, so handling dead leaves or vines can cause a reaction
- If poison ivy is burned and the smoke then inhaled, this rash will appear on the lining of the lungs, causing extreme pain and possibly fatal respiratory difficulty.
- If poison ivy is eaten, the mucus lining of the mouth and digestive tract can be damaged.
- oil transferred from the plant to other objects (such as pet fur) can cause the rash if it comes into contact with the skin.
  (years ago my wife had some terrible cases of poison ivy from petting our family german shepherd)
- clothing, tools, and other objects that have been exposed to the oil should be washed to prevent further transmission

A new factoid for me:
- People who are sensitive to poison ivy can also experience a similar rash from mangoes. Mangoes are in the same family (Anacardiaceae) as poison ivy; the sap of the mango tree and skin of mangoes has a chemical compound similar to urushiol

A plant that can give horrendous dermatitis inflammation is indeed a sap-induced one, from the American Pokeweed, Phytolacca americana, see my SRGC post about the curious dichotomy of the plants herbal usage yet it's extremely toxic properties:
http://www.srgc.org.uk/smf/index.php?topic=6788.msg189034#msg189034

[Hoy]

Interesting treading, Mark!
I am not unfamiliar with rash and blisters caused by plants. The genera Heracleum, Angelica and Euphorbia and also some Ranunculi which are common here do contain a sap that especially when exposed to sunlight give rash and blisters. Once one of my legs was completely covered by blisters caused by Angelica archangelica sap and sunlight and about every other year I get some  blisters if I have been exposed to sap and sun from any of these plants being careless when mowing.

[RickR]

I didn't feel qualified anwering Trond regarding poison ivy rashes, since I have never experience them.  Thank, Mark.  So have you had any reaction to mangos?

[Hoy]

Are you immune or just careful, Rick?

[RickR]

In my early teens, I was definitely immune to poison ivy.  But since that one bout that came to nothing, I have not touched the stuff (to my knowledge), although my clothes have brush against poison ivy from time to time. Allergies can change over time, so I don't tempt fate. I hope I am still immune...

[RickR]

I have now identified a few other species I found in the savannah of Uncas Dunes SNA:

Artemisia ludoviciana ssp. ludoviciana (White Sage)

        


Froelichia floridana var. campestris (Plains Snake-cotton)  Except for a disjunct population in North Dakota, this is the northernmost reach of the species.

        


Gnaphalium obtusifolium (Old Field Balsam)  The flowers don't get any better on this one either...

        


Lithospermum caroliniense var. croceum (Carolina puccoon) and a single seed.

                

[Hoy]

The Lithospermum  seems to be gardenworthy, at least I like the leaves!

[McDonough]

Yeah, I like the Lithospermum too.  I have tried a number of our native yellow-flowered ones, some are beautiful plants, but have not had any luck with them yet.  I had to look up Lithospermum caroliniense var. croceum to see what the plant looks like in flower, a most garden worthy species.  Here are some links.

http://plants.usda.gov/java/largeImage?imageID=licac9_001_ahp.tif
http://wisplants.uwsp.edu/scripts/detail.asp?SpCode=LITCARsCRO
http://minnesotaseasons.com/Plants/hairy_puccoon.html
http://indianadunes.lifedesks.org/pages/10173
http://www.keiriosity.com/gallery/main.php/v/plants/Boraginaceae/Lithospermum_caroliniense_var_croceum/Lithospermum_caroliniense_var_croceum15.jpg.html

[Lori S.]

Oooh, very nice!  Quite reminiscent of Lithospermum canescens, hoary puccoon, of the eastern prairies.

[RickR]

Actually, that was the first time I had seen Lithospermum caroliniense; L. canescens is fairly common (in the right places) here in Minnesota.