School Assignment: How do I figure out the names of plants for a Bio project?

I have to pick 20 wild plants and somehow name them. Where do I start? you guys might get mad if I posted all 20 (I only have 6 so far, I have pics too.

Edit: http://s300.photobucket.com/albums/nn29/Z-Overlord/Bio Project/

 

You asked so nicely you deserve a few answers. The problem is the photos may be a bit unclear. I can tell they are dry area plants but that is about it. Hopefully some of the locals can help;

Liz

 

3. Ricinus communis

 

#1 is Jojoba Simmondsia chinensis.
#2 is a sumac Rhus, or close relative.
#3 agree with Castor-oil Plant Ricinus communis. Warning: dangerously poisonous if eaten!
#4 not sure!
#5 looks like a willow Salix, tho' i'm not 100% sure on that.
#6 could also be Jojoba.

 

could #4 be broom (common name)? I'm very allergic to it and that was the first name to come to mind.

 

No, not broom; wrong leaf structure.