Perhaps a Silphium. S. perfoliatum or integrifolium?

Thanks, peren, but these were in woods on a ridge with granite outcrops. Silphium doesn't fit. I'm guessing there will be flowers by May, so I'll just have to return.

I sadly don't know it, but it looks very lactuca-esque to me. Did it bleed white? I wouldn't be surprised to see little yellow weedy flowers at the top... Time will tell. The leaves aren't truly perfoliate, correct? They look alternate, right?

Thanks macranthos. There were hundreds of these plants. They were in one of those special places where rare plants are often found, so I didn't pick one for examination. They're definitely not Lactuca. As said in my original post, leaves were clasping and alternate. They were also soft, and rounded at both ends. This will be easy once the flowers appear.

Look at Linaria genistifolia ssp. dalmatica . Dalmation Toadflax

Thanks OF, but not a match. I rechecked them today, and still no flowers. I'll try to remember to post back when they're in bloom.

It looks Lactuca like to me too. There's a typical jagged mature leaf right at the base.

That leaf doesn't belong with the plant in question. Sorry for the misleading photo. If they're not flowering next time I'm on top of the mountain, then I'll pinch one to disprove Lactuca ;)

I went back to this site today. The plants in question were 2-4 feet tall, and had gorgeous spikes as shown below. This one is Streptanthus maculatus (Arkansas Twistflower). You'll see better detail if you click on the photo.

I would have NOT guessed streptanthus from that first picture: the only one in familiar with here is a diminutive woodland waif. Good thing you were able to get back a second time.

Very pretty. Thanks for the update. Not something I'll ever see around here.