Resources:

1. http://www.tcweed.org/Weeds/WeedID.html

2. http://www.mtweed.org/weed_Houndstongue.html

3. http://www.weedawareness.org/hounds.html

4. http://www.cwma.org/nx_plants/ht.htm

5. http://www.unce.unr.edu/publications/files/nr/other/FS9866.pdf