Fuller's Teasel, Dipsacus fullonum, a common sight in open weedy places. As non-native invaders go, this is a pretty spectacular plant and a species familiar to and identifiable by even the most casual of botanists.
Teasels, most of which are indigenous to Europe, were once used in the manufacture of textiles. The incredibly stiff, sharp bracts of the flower heads were used to tease cloth or raise the nap on wool products, and to ensure a ready supply, teasels were planted around cloth plants.
They jumped the garden fence long ago, and have been a part of our landscape for most of the past century. And for most of their life on the lam here in the States and Ohio, it was the lavender-flowered Fuller's Teasel that was the common species.
The short-cylindric flower spikes are actually rather showy, but I never seem to see much in the way of insects nectaring at them. There are over a dozen species of teasels, but only three have shown up here. And one of those, the Indian Teasel, Dipsacus sativus, was only collected from two southern Ohio counties long ago. I've never seen that one.
In the 15+ years since, this white-flowered teasel has marched along our highway system - a common avenue of plant dispersal for non-natives - and has colonized a big chunk of the state. Fernald, in the 8th Edition of Gray's Manual of Botany (1950), states that it is "local" in eastern North America. Tom Cooperrider, in his 1995 Dicotyledoneae of Ohio, records it from 19 rather scattered Ohio counties. Today, I dare say there are specimens of Cut-leaved Teasel to be found in all 88 counties, and in many locales it is locally abundant.
Hmmm... Could be.
But, when this sort of water-retaining structure is present on a plant, one has to wonder about the possible evolution of carnivory. There is no question that insects become trapped in teasel leaf-pools and perish. Does the plant then successfully break down and assimilate the insect's proteins and other valuables? It's probably worth a study.