Question
Hello,I live in Ontario Canada and I have this weed that seems to grow more each year all over my lawn. It grows high and almost resembles a marijuana plant or a mature Kochia weed except the leaves are not spade shaped they are serrated. It has no flowers, it is extremely prickly all over so it is very hard to get rid of by hand. If you can narrow down what you think it might be, please let me know. Thank you very much.

Answer
Hi Tam.
I searched weeds in ontario, and got this page that should help you identify it.
Copy and paste this address into your browser, and click on each weed. You will get pictures of it, and all the info about it's life cycle etc.
Charlotte

http://www.omafra.gov.on.ca/english/crops/field/weeds/problem_weed.htm