Yes, it may be quite toxic: http://www.library.illinois.edu/vex/toxic/cklburs/cklburs.htm http://en.wikipedia.org/wiki/Xanthium_strumarium And the fruits are quite horribly looking, with burs all over which may entangle into the pet's fur. I tried to sprout it from the fruit last year without a success and then just reused the pot for some other plant. However, this year, I discovered two powerful shoots coming from one of the pots. In a month, they displayed the flowers - just like yours. Soon, I expect to see the prickly pods.
