In message , Martin
writes
On Thu, 15 Apr 2010 01:46:11 -0700 (PDT), Rob wrote:


This thread raises an interesting weed-identification issue:
most gardeners want to be able to identify weeds as early as possible
in their development, which normally means BEFORE flowers have formed.
However, most systems (books and websites) rely on flowers for
identification.
That is why I have an old Min. of Ag. pamphlet for farmers to identify
weeds very early in their fields (cotyledon sketches).
I can also recommend the Roger Philips "Weeds" book, which I found
secondhand.
Any other hints ?

I found this
http://weedid.aces.uiuc.edu/

Indiana (University of Indiana at Urbana-Champaign) has a different
flora from Britain. Of there 172 weeds, perhaps 30 can be found here,
and a fair number of them are under different names.
--
Stewart Robert Hinsley