Sweet oxeye, Heliopsis helianthoides
 
Sweet oxeye looks like a cosmos by itself. These plants are brimming with life that feeds on them.
Dark yellow flowers start blooming early in the summer and bloom for many months. Deadheading can even prolong the bloom time. 
 
Ecology:
Sweet oxeye is a powerful plant. I always feel it's like the garden market. Everything is happening around and on it. Male bumble bees hang from flowers or cuddle up in them to sleep, and birds like chickadees, kinglets and woodpeckers graze the stems for insects. These insects can be aphids, ants and spiders ;-). We can learn to live with them and see a whole ecosystem develop around them. Soon, predatory insects like ladybugs, wasps and soldier beetles will keep them in check. 
 
Birds love the seeds in the fall and snack on insects on their stems from spring into winter.
No other plant has such an active food web on display. Therefore, sweet oxeye is a messy plant. You have to be ready for it. There is no point in fighting aphids and with them many beneficial insects in the egg and larval stages.
 
Because of their open shape, the flowers welcome many bee species, butterflies and flies to enjoy their pollen and nectar.
 
Growing conditions:
Sweet oxeye is a tough plant. It can grow in pretty much any conditions, just not shade. It will spread by rhizomes and needs some space.