Wednesday, August 30, 2023

Explore Outdoors ~ Disc Flowers on a Coneflower

 I've been watching pollinators on my coneflowers week after week - butterflies, flies, bees of all types. But I never really thought about the flowers producing the pollen that the bees were collecting.

So a couple of weeks ago I followed a leafcutter bee around. And I noticed that the conehead of my purple coneflowers had tiny pollen-laden stars on the disc flowers.

Okay, a digression: composites have disc flowers and ray flowers. In the coneflower, the ray flowers are the purple petals and the disc flowers are the ones that make up the center cone that looks a bit like a porcupine.

At first, I thought that the pollen was on top of the orange spike of the disc flower.

Then I looked closer...

Turns out each "porcupine quill" is a bracht, and the flowers are next to it. When you look closely (a handlens is helpful) you can see the two-lobed stigma and the star-like anthers.

 According to the Outdoor Learning Lab (Greenfield Community College), the disc flowers mature sequentially, beginning with those on the perimeter and moving toward the center. Only one whorl of flowers matures each morning, and there is only a small amount of nectar - so pollinators have to visit many flowers on one plant and then visit more on another plant. What a great way to ensure cross-pollination! You can read more about coneflowers at the OLL page here.

 This week take a close look at composite flowers you find in your neighborhood. They might be coneflowers or sunflowers, black-eyed Susans or ox-eye daisies, asters or fleabane, or even dandelions and their relatives. If you have a magnifying lens, take it with you.

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