Here we have yesterday's goldenrod, growing harmoniously next to an aster, most likely Aster novae-angliae, or New England aster.
Sharp plantsmen will be thinking right now, 'But it's not an Aster any more.' And that's true. These days, most North American asters are now in the Symphyotrichum genus, which is decidedly more of a mouthful.
For a time, there were 600 different species of Aster globally, which could become quite confusing. So, after studying the plant structure more closely, the Angiosperm Phylogeny Group reclassified these plants into new genera. Technically, European asters are the only plants that belong in the Aster genus, though nurserymen still refer to the new world plants as Aster, too.
The word Aster derives from the Greek word astron, which means 'star', and most likely refers to the flower structure. In fact, all geni in the Asteraceae family are characterized by their showy flowers, commonly called composite flowers.
If you look at the photo above, what appears to be one flower is actually a collection of hundreds of flowers. Composite flowers are a collection of many small, teeny-tiny flowers. In fact, there are two types of flowers in this photo above. The purple 'petals' are ray flowers and the yellow 'petals' make up the disc flowers.
This kind of adaptation is relatively young in the world of flowering plants (angiosperms) and it's very successful. That's why so many 'weeds' have a daisy or aster like flower. The great increase in flower quantity is a surefire way to ensure a plant's success.