Cowpen Daisy is listed as invasive in Hawaii and other Pacific islands. Is there any danger of that in the continental U.S.?

Not as far as I know, I have never seen it listed as an invasive.
Besides since it is a native plant it wouldn't be considered invasive even if it was super abundant,
in that case it would be considered aggressive.
I think that in tropical climates it might become aggressive since it probably won't dye back for the winter, as it does here in North America. .

" The species is considered as an intruder, which spreads over fertile land and prevents development of any other local species in the area, due to its high propagation & density. Research elucidates to an allelopathic behavior of the plant[5] which explains its advantage, or takeover, over other species." This I copied from the Wikipedia article that needs expansion. Obviously its introduction requires caution. However it is very attractive and easy care. The question of native or alien is very much a human construct. What may be native to a specific area, may not be so even in a nearby region. Its introduction could spread its distribution beyond bounds. It is considered a invasive weed in Queensland, AU. Native to the US does not mean native to your particular site within the US, so perhaps before going ahead one should check out whether one can become a non-voluntary agent of a obnoxious weed with some local agricultural extension agency. If however given those checks there doesn't seem any risk of getting out of bounds then go ahead! It is very attractive!

I found more info.( source Flora Argentina in Spanish): It is a native annual ( therefore a worthwhile wildflower in a prarie garden) in central, and northern parts of Argentina, also contiguous Uruguay, Paraguay, Bolivia and Chile. I suppose that it is hardly improbable for it to survive in the cold regions of Patagonia. I'm supposing that it would have naturally dispersed here. Still with its intruding capacity I would be cautious.

This map shows the states in the US where the plant is native.
http://plants.usda.gov/core/pr...

Thank you Ann, that is very nice of you.

My pleasure Josephine.

Looks like it is native to Tennessee. I think I have seen wild flowers along the roadside that look something like these. We have so many native yellow wild flowers here in West TN. The most beautiful in my opinion is the wild rudbeckia, or black eye Susan's.

Yes Donna, the Back Eyed Susans are very beautiful and I love them too.

Me three!

I enjoy them also! However, I have to plant seed and water them, otherwise they'd eventually die out. There's one place I pass by sometimes on my way to Lakehills where lots of them do flourish somehow...I don't think they have to plant seeds. They have horses. I wonder if what the horses just naturally provided over the years to what was originally just a light dusting of soil over caliche and limestone gave the Cowpen Daisy plants what they needed. In other words, fertile soil deep enough for them to survive and get the seeds going!

Yes, I don't think they like to grow in caliche.

My question re this plant - gardening in zone 4-5, do the seeds it releases make it through a cold winter? Does anyone know? I am not sure I have seen it for sale locally, which makes me wonder. Interesting that map shows it in Michigan and NY state but not Wisconsin.

I really don't know how cold hardy this plant would be, but I think it could be grown as an annual in cold climates.
Unfortunately wildflowers are not very much promoted by nurseries because they may be difficult to grow and not profitable for them.

I, too, love this plant. Where I live (north of San Antonio) it self-seeds, but I usually have several people lined up and waiting for giveaway volunteers. The bees and butterflies like the nectar - and the deer leave it alone. It blooms profusely and requires little water. All good things in my opinion. It also serves as a larval food for the Bordered Patch butterfly!

Wow!! that is gorgeous, I love the Bordered Patch, thanks for the good report

I live in Grapevine, Tx, between Dallas and Ft. worth. A neighbor has seedlings (numerous!) of Cow Pen Daisy. I was considering planting a few in my perennial bed. I can deal with a prolific reseeder, but recently read that this plant produces chemicals that kill other plants that grow too close. Well...how close is too close? Would this be a problem for established plants, or just other seedlings or newly planted things? Does anyone have info on this?

I grow Cowpen Daisy and I love it. I have never heard of it being detrimental to other plants.
It is an annual and it grows fast but is very easy to pull, I just thin out what I don't want.
Since it grows fast it might shade out other slow growing plants nearby, but you can control that part.
I think the benefits in nectar and larval food far outweigh any drawbacks this plant might have.