In message
,
jmbillings writes
In the grounds of my office is a thistle I couldn't recognise from a
quick hunt online.

It is tall (at least 5 ft) and some points I noted were that it has
some short sharp barbs on the flats of the leaves, and also on the
stem- the ones on the stem start out sparse and get closer/smaller the
nearer to the next section where branches come out, then the process
repeats. It also had spiky green balls on the tops.

I found images of the bull, musk, spear and canada thistles online but
none looked entirely right...

I understand that a picture would probably be helpful, but I didn't
get one. Not sure if the above is really enough to go on though!

This is a UK (United Kingdom) newsgroup. However your selection of
species names suggests that you are somewhere else - or did you just
pick up the vernacular names during your search?. We may not be able to
help you, but we would have a better chance if we knew where you are.

(For UK readers Canada thistle is, fide Wikipedia, the plant we know as
field or creeping thistle - Cirsium arvense. To add to the confusion,
fide Wikipedia again, both bull and spear thistle are Cirsium vulgare.

The third common species in the UK (I've only ever once seen musk
thistle) is marsh thistle - Cirsium palustre. It seems as good a match
as anything.
--
Stewart Robert Hinsley