A google.com search on Dipsacus dispersal produces a lot of hits. It is
an invasive species in the U.S. and Canada so has been studied a lot.
The study "Dispersal of Dipsacus laciniatus seed along an interstate
corridor and a natural area" by R. N. Wiedenmann ) and
A. Musser, Illinois Natural History Survey and J. D. Parrish, Millikin
University concluded it was wind dispersed and traveled a maximum of 15
meters along a highway.
http://66.102.7.104/search?q=cache:V...ispersal&hl=en
The following webpages indicates other important modes of dispersal as
water, highway mowing equipment, highway construction, cultivation and
humans disposing of flower arrangements containing teasel. It has
spread particularly along the interstate highway system. Its use in
flower arrangements is blamed for its spreading to cemetaries.
http://dnr.wi.gov/invasives/fact/teasel_com.htm
http://www.inhs.uiuc.edu/chf/outreach/VMG/teasel.html
http://www.mdc.mo.gov/nathis/exotic/vegman/ten.htm
Dipsacus fullonum L. was named by Linneaus (1707-1778). William Hudson
(1730-1793) seemingly believed D. sylvestris Huds. represented a
separate species because the bracts on the receptacle have a straight
barbed awn according to Bailey's Manual of Cultivated Plants. D.
fullonum seems to have a recurved awn. Such a minor difference is
apparently not considered enough to represent a separate species by
most taxonomists today so D. sylvestris is either a subspecies,
Dipsacus fullonum subsp. sylvestris, or merely a synonym for D.
fullonum. The references that are listing D. sylvestris seem out of
date. Britton and Brown's influential 1913 flora listed D. sylvestris
as did Asa Gray's 1908 Manual of Botany so that may have given the name
staying power. You might try to look up Hudson's original description
for D. sylvestris and see why he thought it was a separate species from
D. fullonum or if it was merely a case of his independently describing
the same species as Linnaeus given that were contemporaries.
The following reference says in the U.S., D. sylvestris is used for the
cultivated teasel and D. fullonum for the wild teasel. The opposite is
done in Europe.
http://ucce.ucdavis.edu/files/fileli...5319/17400.pdf
Dipsacus is not usually considered carnivorous because it has no
enzymes to digest trapped animals. I'm not sure if there have been
research studies that examined if the trapped animals provide a benefit
to the plant. I'm sure it's possible that they could provide a small
benefit because foliar fertilization of plants can be beneficial. Tank
bromeliads can drown animals too but they are not usually considered
carnivorous. The phenomenon of plants retaining small, open pools of
water is termed phytotelmata.
http://www.canopyants.com/treehole.html
http://bromeliadbiota.ifas.ufl.edu/bromfit.htm
You might wish to check the following databases for Dipsacus:
http://www.ingentaconnect.com/
http://www.pubmedcentral.nih.gov/
http://agricola.nal.usda.gov/
David R. Hershey