Poison Oak Info:
Yuk! I hate Poison Oak. But there's hope. First, you need to learn to identify it--check out a picture. Poison Oak's name is Toxicodendron diversilobum because it is toxic and is very diverse. It can grow as a vine, a small herbaceous plant, or even a woody tree! Second you need to prevent it. The best method I've found is to use Tecnu. Its good stuff! Its a special soap for Poison Oak. After you ride, (after EVERY ride) slap some of this stuff on, and you'll be set. I very rarely get poison oak after using Tecnu. By the way, Poison Oak doesn't grow above three or four thousand feet -- incentive for high elevation rides!
Here's some more info on the dreaded plant:
Tec Labs Inc
Poison Oak Faq
Some Science Stuff on Poison Oak
Star Thistle is the yellow prickly things that hang over the trail and put a million holes in your shins. Yes we all hate them. They poison horses, making them go crazy. They prick and poke cyclists, making them go crazy. Its scientific name is Centaurea Solstitialis. I'm told its a bi-annual plant so the weather last year has caused it to be so prevalent this year. Dike 8 and Clementine Loop are pretty bad. The Star Thistle just started blooming at the beginning of July, so by the end of July they will be pricking us to death!! BOOHOO.
Some articles about Star Thistle:
Stanford Research (that's right, even Stanford is attacking Star Thistle).
Disease in horses