Carol, you sure are dedicated!
Here she tags the awfulest stuff on the Preserve, Stinging Nettle. She was very careful not to touch the leaves because they have thousands of tiny hairs that inject a chemical that is extremely irritating to the skin.
If you are unfortunate enough to experience this irritation, here's a few remedies to try:
Mugwort... California Mugwort (Wormwood) is a natural antidote for Stinging Nettle. You can usually find a patch of it it growing nearby the nettle. Just snap off some green leaves and rub onto skin rash every 20 minutes or so. (this is your best bet for immediate treatment)
tape... lay tape over the area and remove quickly. This should remove some of the tiny hairs. (just what every hiker carries in the pack)
ice... ice down the area for several minutes. The Yockuts Indians used to harvest this plant after the first hard frost without any discomfort. So a good 'frost' should neutralize the irritating chemical. (this works even after several hours)
mud... mud is a universal soothing substance. (during dry periods - make your own!)