I saw these growing up to the eaves at a local garage sale and admired them four years ago in the late fall. The lady dug me up a few tubers and I brought them home to plant in the corner by my chain link fence to disguise the telephone pole right outside my yard and to brighten up what was usually a dull area with an empty field behind it. They were slow to appear the following spring but once they started there was no stopping them. Each year they spread even more. Right now I'm looking at a cluster close to 10 feet tall and at least 10 feet across. The flowers are abundant and look just like the ones in your picture. They make an excellent cut flower but require replacing the water in the vase almost daily. The ones in my kitchen have been there over a week and show no sign of wilting. I'm now referred to as "the lady with the big yellow flowers."