Swamp Sunflower, Helianthus angustifolius, started flowering today. This is the latest flowering of our native sunflowers. This is a young plant I got from my recent trip to the Mt. Cuba Center, but despite it's age and limited flowers finding bees on it isn't uncommon. Sadly it's still rare enough that I can't get a good picture. Flowers are about the size of a Black-eyed Susan but I've read the plant itself can grow to be around 8' tall. Next year I'm expecting this to be a real show stopper. The flowers are so bright and happy looking they stand out even more than the Goldenrods in my garden.
Another trait I like is the dark center of the flower. I also have Helianthus maximiliani but I find the flowers to be boring because the centers are either yellow, orange, or a pale brown at best.
This species also goes by the name Narrow-leaf Sunflower because the leaves are narrow and grass-like. Here you can barely make them out with some of the overgrown toughs of lawn along the garden boarder.
Seeds to perennial sunflowers are an important food sources to over wintering birds. Sadly almost all of our native sunflowers are aggressive spreading plants and may require thinning our ever few years.