Ellen,

Poisonwood (is this the right name?) looks like a tree version of poison
oak. Leaves have three leaflets, often with a bit of red on the petiole
(leaf stalk). The leaves are glossy and have rounded lobes like that of the
North American shrub poison oak. The trees would make good ornamentals
otherwise.

I suppose this is a good time to review poison ivy as well. Poison ivy, the
allergenic scourge of North American forests, prefers disturbed ground,
which includes almost all the woods that anyone is likely to encounter east
of the Mississippi River, but particularly the edges of woods, riverbanks,
clearings, and other areas where trees have recently fallen or been cut.
Leaves are glossy and split into three leaflets that can have smooth
margins, but more often have one or a very few tooth-like lobes. All parts
of the plant are allergenic, including roots, berries, and even the smoke
from burning plants (very dangerous, as it can cause an allergenic reaction
in the lungs). The plant generally grows as an herb, sometimes as a low
shrub; often as a vine with reddish, hairy roots clinging to tree trunks. If
you're not very allergic to the plant, you can try wearing boots and long
trousers, tucking the trousers into the boots. Then if you encounter areas
blanketed with poison ivy in the woods, you can walk directly on the plants
rather than brushing through them, and thus minimize your exposure. Do
change your trousers each day, and turn them inside out to avoid touching
the outside. Don't rest your hands on your knees if they've been exposed to
poison ivy, don't reach around tree trunks if they might have poison ivy
vines on the other side, don't walk through the woods in the dark while
wearing shorts, and don't pet your dog after it's been playing in poison
ivy. And generally when walking through poison ivy and thereafter, it's a
good idea not to scratch itches or touch your skin, just in case your
fingers are carrying the dread allergenic oil. Wash thoroughly when you get
home.

What do you do when it's too late, and you've Touched the Leaves? Swift
amputation is the only sure cure ...OH all right, that was just a joke.
Opinions differ sharply on what to do next, and I suppose experience is the
best teacher. My own 2 cents: Wash it immediately in plain water, don't rub
or touch the exposed area, and you'll probably escape the worst of it. If
you use soap, that might remove protective skin oils and make the next
exposure worse. So if you do use soap, do it immediately and thoroughly.
Some people recommend rubbing yourself with the juice of various herbs such
as touch-me-not. Touch-me-not is not very common in the Alabama forests, so
I've never been able to try it. Hmm, touch-me-not would make a better name
for poison ivy, would it not?

For the benefit of non-North Americans, what happens if you Get Poison Ivy?
Well, for the first day or two, nothing at all. Then the exposed skin begins
to itch and itch, and red blisters appear. If you scratch them and they
break, you risk spreading the allergenic oil to other areas of skin, and
also risk infection and scarring, so it's recommended that you not do that.
I find the best method is to ignore the itch. Other remedies: bathing with
some vinegar added to the water; calamine lotion to dry the blisters. I used
to know a medical technician who would rub his blisters vigorously with
hydrogen peroxide, just once, then leave them alone. That seemed to rid him
of the oil, but I'm not sure whether it might cause scarring in delicate
skin.

Some other woodland plants have three leaflets; look for a dab of red on the
petiole. Similar, but harmless, plants include Virginia creeper, a vine with
five leaflets instead of three; and box elder, which has three leaflets but
is a maple and eventually grows to tree size.

If I'm not mistaken, poison ivy, poison oak, poison sumac and related
white-berried, allergenic plants can be split off as genus Toxicodendron, or
alternatively lumped with their red-berried, innocuous relatives (other
sumacs, bearberry, etc.) in genus Rhus. I used to make a sort of herbal
lemonade by dipping red sumac berry clusters in water and straining the
little hairs out through a cloth, as recommended in the Boy Scout Manual.
It's tasty and refreshing, but sometimes a little irritating to the urinary
tract. Don't try this with any of the white-berried species, or indeed with
any species whose identification is uncertain.

Can't help you with the other questions. Have a nice trip.

Andrew K. Rindsberg
Geological Survey of Alabama