Just read up on them, and they sound pretty imposing. My New England Wildflower Society book said they will seed themselves, and can be difficult to remove once established, as they form very deep, resprouting tap roots. So I guess you'd better be sure to pull up seedlings you don't want right away. It also said they are called Cup Plants because the leaves form little bowls that hold rain water, a handy place for the birds to wash down their seeds!

Planted one in the spring, though not in bloom yet.
The reason I planted is because it is suppose to take over and reseed itself quite well.

These grow all over a damp meadow near where I work and they are HUGE. The goldfinches love them to death. I haven't seen much else besides chickadees on them, though, but I'm not there during prime birding hours. They look like they could be tough to get rid of once they get started...but maybe drier soil will keep them more modest.

We have a related type of small-bloom wild sunflower in our
yard, yes, they re-seed and are vigorous growers. They are
not all that difficult to pull when young, if the soil is
damp from recent rainfall. Every spring I pull out some of
the volunteers, and allow others to grow to maturity.

Well, the Cup Plant is still in its pot because I haven't had a chance to plant it yet. We have lots of Goldginches visit here already because I have an upside down thistle feeder that they like and annual sunflowers, which they adore. Usually they pluck the sunflower pedels off, at least on the top of the flower, so they can sit and reach the seeds easier. This morning I noticed that the one open bloom on the Cup Plant (there are lots of other buds) had all the petals plucked just as the Goldfinches like to do on the annual sunflowers. So I know that they have been checking the plant out already.

Since we had rain, I got a chance to see for myself why they are called Cup Plant, with the little water holders the way the leaves grow.

The Cup Plant is a member of the Aster Family. The leaves join at the stems and form little cups where water settles. Birds love to sip from these small pools. The Cup Plant is a typical tall grass prairie plant and grows up to 8 feet in height. The roots of prairie plants are very very long and sometimes can be almost 2/3 as long as the height of the plant itself. This is one of the ways this plant has adapted to prairie conditions the roots stay cool and moist during long periods of heat and drought.
Pick a permanent place for this plant it's not easy to move that long tap root. VAL

I don't grow any silphiums, but according to Prairie Nursery's catalog, it wants a medium to wet area and sun. Most prairie species do self-seed, and because they develop extensive root systems it's important to pull up the seedlings you don't want during the first growing season--otherwise you can't get them out. I have no idea if this species is aggressive but it doesn't sound like a plant for a small area.

The only really tall prairie plant I grow is ironweed (about 8 feet), which spreads slowly but doesn't seem to self-seed. It attracts loads of butterflies, and I assume that the birds get most of the seeds.

I have a two year old cupplant that is about 10 feet tall and has spread to form a clump of about 8 stems. The sunflower-like blooms are very showy and last for weeks (still blooming here). Bees seem to be most attracted to the flowers and the seeds are attractive to birds. I have it growing near water in full sun. In drier soil this plant doesn't get nearly as tall. It is not invasive but it gets very big and forms large clumps. Makes a great vertical accent.

The Cup Plant is planted in its new home but long since finished flowering. Since its planted, I haven't noticed any Goldfinces near it but then there is always next year.
I like the plant and the flowers are very striking.

The birds love them both for their seeds and for the water they hold in their "cup" after a rain. They are tall and they do spread. Use them for the back row of your garden. I know someone who made a living fence out of them and it is magnificent.

they also seed all over the place. they are great for wetish spots.

Laura

Stake it, Rita. Mine is about 10' tall but it's horizontal instead of vertical.

I find the native Joe Pye weed much more invasive than cup plant.

I didn't need to stake it this year as its not even four feet tall. I don't doubt that it will be much bigger next year. I did finially see some Goldfinches eating on it yesterday.

I didn't plant it where I was originially going to put it but instead put it on the corner back of the hilly area where I plant annual sunflowers, grain sorghum, grain amaranth and mexican sunflowers. All for the Goldfinches to eat the seeds (they do) and also attract hummers and butterflies (they do that too!).

Going back to what newjerseytea said about the Joe Pye Weed being more invasive than the Cup Plant, I too find lots of little Joe Pye Weed Plants popping up all around the yard. No big deal, easy enough to pull out any I don't want. I never dead head my flowers so that they set seed for the birds to eat. So I am always amazed to see what pops up all around.

Well, the Cup Plant is starting to grow this Spring so obviously it made it thru the Winter.

Its about four feet tall now and nice and healthy and green. There are more stems than last year so there should be more flowers later.

Newyorkrita, I tied mine up the other day - did not stake it, but just put twine around it. Am hoping it won't collapse this year as it did last. I've planted two more 'cause I love it so much.

Well, it's at least 8 feet tall now and blooming away. The Goldfinches go on it to check out the flowers but they are not seeding yet so they have to wait. I saw one Goldfinch drink water from the little 'cup' in the stem after a rain so I guess they really go like the natural water source!

Goldfinches ate up the seeds of the Cup Plants this Fall. I always see them back there as birds love to hang out back there and eat the seeds off the Cup Plant, Foxtail Milet, Ragweed, and Grain Amaranth growing there.

Well, the Cup Plant came back bigger than ever this Spring!