Ah, sunflowers! Here we have Helianthus annuus, the annual Sunflower. This photo is from the Nature Conservancy’s Tallgrass Prairie Preserve in Kansas. I was there last September and the sunflowers were in full glory along the roadsides and in the meadows at the preserve.
One thing I love about the whole Sunflower family is its amazing diversity. Over 32,000 known species in over 1,900 genera. It is the largest family of dicots. All flowers in this family are compound – with either disk flowers (the center) or ray flowers (each of what looks like petals is a flower!) or both disk and ray flowers. Each ‘flower’ is a bouquet of dozens, such a feast for pollinators!
In this photo you can see some tiny yellow disk flowers blooming. The first ones start in the center and they bloom sequentially, in a kind of wave. The broad yellow petals are actually ray flowers with five compressed petals which you can see as lines or linear markings. The ray flowers may not be fertile – their job is to be signal flags for the fertile disk flowers.
In the fall, seeds will ripen from all the disk flowers that were pollinated and fertilized. The dead ‘flower’ heads are beautiful in themselves. Interlocking spirals of seeds providing bounty for birds through fall migration and perhaps later.
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