It has been sprouting all over my garden and seems extremely hard to kill. I've been trying to look up information on it but nobody in the area seems to know the name, even though it seems to be growing all over Israel.
It looks like 'bur ragweed', Ambrosia confertiflora to me. However, you need the inflorescence (or sometimes the fruit) to ID the Ambrosia genera. It does not really matter as you deal with most of the genera the same way. These are considered weeds in Israel. http://www.sviva.gov.il/InfoServices/ReservoirInfo/DocLib2/Publications/P0701-P0800/P0707.pdf