In message , Ian Wilson
writes
Good morning folks

I've just found the group and enjoyed browsing around the helpful (&
occasionally not so helpful:-) comments & discussions.

I'm planning my undergraduate dissertation at the moment and would
appreciate any thoughts, input and suggestions that anyone might be
able to make.

I plan to measure the effects of leaf axil pools on reproductive
fitness in Dipsacus fullonum, the Wild Teasel, by measuring pollen &
seed production in 3 groups - one with regularly topped-up leaf axils,
one with drained axils and a control.

Whilst the old question of whether there is any degree of carnivoury in
D fullonum is interesting, I want to try going back a step to see if I
can measure any increase in fitness based just on the presence of axil
pools without trying (at this stage) to pin down a specific mechanism.

There are a few specific questions which have arisen from my reading
about Dipsacus.

1. Is there a clear difference between D fullonum and D sylvestris.
Many US studies refer to D sylvestris and I would expect 2 different
latin names to be different species but I have seen it suggested that
they are synonyms for 1 species. (should I expect long diatribes on
what constitutes a species here? I will read them with interest without
even TRYING to add anything useful!)

INRA, URL:http://www.dijon.inra.fr/flore-france/di-dn.htm has D.
sylvestris as a synonym of D. fullonum.

2. Does anyone have any experience of dispersal in D fullonum?
Particularly could the seeds survive a trip through the gut of a finch?
Everything I've read seems to suggest the it simply drops seeds
locally, but as it is a coloniser of disturbed ground this method od
dispersal seems inadequate. I may have to spend too much time this
autumn copying Darwin & trying to germinate bird shit!! I guess if it's
good enough for Darwin...
I wonder whether D fullonum could be "hitching a ride" on something
like a thistle by being excreted on disturbed ground which the thistle
seed has floated to by a bird which is eating the seeds of both plants.
This is very speculative, but would be a nice mechanism if it could be
seen in action!

I've assumed, on no good grounds, that seeds of teasel are dispersed by
attaching to the plumage/pelage of animals.

3. Any comments on where people are finding teasels growing (either as
isolated plants or clumps) would be very helpful, as would any
information on what might limit teasel distribution and growth. Around
here (Northampton, UK) where Hemlock (Conium maculatum) grows well it
clearly seems to outcompete the Teasels, but close by there may be
ground where the Hemlock does poorly and the teasels seem to be growing
well.

4. Whilst I said that I'm not looking at carnivoury; any tales of large
or unusual organisms found in Tease axils would be very interesting.
Here they seem to particularly enjoy drowning molluscs. The smell of a
teasel with 4 or 5 decaying molluscs on board is really beyond compare!

I appreciate that I am asking a lot but I am becoming somewhat obsessed
by this fascinating plant and any info would be very warmly received.

Many many thanks

Ian Wilson

--
Stewart Robert Hinsley