Large one is a Populus species I believe.

??? I'm new to gardening and don't know what most of these terms mean. Know of anything a little simpler ie dark green leaves, flower stalk, hairy leaves, perennials, 12 - 18" high, sun/pt. shade. Like I said simple terms. LOL I don't mind spending the time on line searching, but have found that most of the sites don't show the foliage at all and go by the flower colour. I sure wish I had a digi camera. Guess I'm going to have to wait until it blooms, with my luck I'll be away when it does! Nett

Matt, That's a succulent Euphorbia and a wonderful example of convergent evolution. It's likely from the Old World and is looking in the pink, metaphorically speaking, of health. The leaf drop is a normal cycle, as many of the cactoid Euphorbias grow vestigal leaves in the early part of their growth time.

Some kind of tickseed. (And yes, I had to click calliope's link. Thank you, calliope.) Tickseed is named after the shape of the seed, which resembles a tick. According to wikipedia, it may refer to several plants in any of 4 genera: Bidens, Coreopsis, Corispermum, or Desmodium. I didn't know that, so at least I learned something new even if the OP didn't. Here is a link that might be useful: Tickseed