Dipsacus identity

[Tom]

    There is a white flowered Dipsacus that has been appearing in our area (Virginia-West Virginia), quite different from D. fullonum. The leaves join to form a cup around the stem rather than simply adjoining, flowers and anthers are larger, bracts are somewhat foliaceus on the margins though still stiff, scales subtending the flowers are slightly recurved and those at the top of the spike are considerably longer than the others, and, lastly, it has fewer but perhaps slightly larger prickles on the stem and leaves. The only name I'm able to find that may apply is D. laciniatus, but that species seems always to be described and illustrated as having cut leaves whereas this plant seems to have uncut and merely serrate leaf margins. Can anyone tell me if this is, nevertheless, D. laciniatus or something else. If it is laciniatus, is what we're seeing here normal and ordinary. Thanks.

Thomas F. Wieboldt, Assoc. Curator
Massey Herbarium
Dept. of Biology
VPI & SU, Blacksburg, Va. 24061