Fuller's Teasel

Fuller's Teasel
Dipsacus fullonum
Dipsacaceae (Teasel Family)

Quick ID
Prickly thistle-like plants that are generally about five feet tall, although I've seen plenty reach the ten foot mark.  They're biennials, forming a rosette of leaves the first year and flowering the second season.  Flowers are light purple little tubes tucked into a spiny seedhead that perches atop the bristly stem like a pinecone.
Range
Fuller's teasel is native to Europe, and was first cultivated in the US in the 1800s.  It naturalized quickly and is now found growing wild all over the country, except in the northern Great Plains and some states in the southeast.  Look for big patches in moist areas by roadsides and other places where the soil has been disturbed.

What's in a Name?
The genus Dipsacus comes from the Greek "dipsa," meaning thirst.  This is in reference to the leaves, which close around the stem to make a little cup where water collects. Studies have shown that the more insects that land in these cups, the more seeds a teasel plant will form, which implies that Dipsacus is at least partially carnivorous.  Rawrrr!
The species name is fullonum, pertaining to fullers (people who cleanse and process wool into cloth).  Traditionally, dried heads of teasel were used for this purpose, attached to spindles and "teased" through wool to clean out dirt and raise the nap of the fabric.

Nowadays the industry uses wool cards (which look like a brush for a kitty), but some purists use the pointy, hooked seed heads still today.  Apparently, when there's a lot of resistance in the fabric, the easily-replaced teasel head just breaks, whereas metal cards will rip the cloth.

Tidbits
The stems of teasel are hollow, making them perfect for building a Wild House of Bees!  In spring, solitary cavity-nesting bees will fill these tubes with a row of eggs, which will hatch and pupate over the summer.  The young bees spend the winter in the stems, and emerge in spring to begin the process anew.  They survive by feeding on a little pollen reserve (or in the case of wasps, a meaty little insect body) left by the mother in the nest cells.  Did you know that insects in the order Hymenoptera (bees, wasps and ants) are the only insects in the world that provide food for their offspring?  Awesome.  
Wild Gardening

By most accounts, you probably shouldn't grow teasel in the garden.  It's at least some level of noxious weed in Colorado, Iowa, Missouri and New Mexico, and has invasive tendencies wherever it gets established.  That said, the spiny seed heads are awfully pretty, and especially nice for dried flower arrangements.  But remember that human dispersal is the number one way teasel seeds are spread, and once it gets out into the environment, it can quickly crowd out native plants.  Using dried seed heads in floral arrangements that are going to leave your house is probably not a good idea.  Better idea--find a wild patch, pull up the stalks, trash the seed heads, and use the stems to build little native pollinator habitats.  Everybody wins!