The aboveground parts of mullein (Verbascum spp.) are covered in itchy hairs.
And yes, that includes the flowers.
So when I make a mullein oil (on a waterbath), I don't strain through a cheesecloth, no, I use a large coffee filter and let things drip through overnight.
When I make a mullein tea, I don't strain through a sieve, no, it's a coffee filter.
And when I make a mullein tincture, that, too, is strained through a coffee filter - unless I percolated, in which case straining through something rather tighter than a sieve or a cheesecloth is included in the making of the tincture.
The roots aren't covered in hair, and they're fairly nice for things like tightening up the trigone muscle at the base of the bladder. It helps with incontinence. Of course, doing kegels helps even more, so combine the two if you're dribbling as you walk, or sit, or cough, or sneeze. Jim uses the root for other things, but I forget what. Jim?