|Its the flowers that are supposed to be showy, the plant itself is not because it does not have nearly as many flowers as H. maximiliani or H. grosseserratus. I think its also called H. pauciflorus, a species I saw in another reference book.|
Showy sunflower is a perennial sunflower that the guide books say is supposed to reach only 2 to 6.5 feet, but then in their second year mine got around to 8 feet high, probably again as with the other perennial sunflowers this is due to over watering. This species has many fewer flowers than H. maximiliani and H. grosseserratus but they are a little larger and the centers are darkish purple. Leaves are large at the bottom of the plant and small at the top, with flowers on long stems. If you're looking for impressive color then this sunflower is probably not worth growing.
This plant is a perennial and the roots will send out many sprouts in the second and following years, most of which I've pruned away. ALL THESE SPROUTS GET TO BE A REAL NUISANCE. You'll be overwhelmed with these things coming up all over the place. This makes it a bad candidate for a small garden.