A good place to land

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A good place to land

In an impulse you pick a fluffy head of a dandelion, breath in and blow the stem clear. Hundreds fluffy seeds fill the air. On their way to find a place for growing into a new dandelion. How do those seed know the best place?

When you look up close at a dandelion seed you will see a stick, with at the top a bit of fluff. This fluff keeps the seed in the air. Researchers from United Kingdom and France found out that in a humid environment this fluff is less fluffy. The hairs of the fluff come together, closing. The seed lands on the ground, ready to quickly germinate in this humid environment.

Zoom in further, to where the stick meets the fluff. You will see a flat top, with all around hairs attached to the side. Sticking out in all directions, right up, but mainly to the side. A fluffy ball of fluff. Researchers placed a fluffy seed in a humid environment. They noticed the top of the stick absorbing water. Making it swell. The flat top was rounding upwards. More hairs are sticking up. The fluff is not fluffy anymore.

To swell like that, to make the hairs stick straight up, this is an art. For this, so the researchers found out, the plant uses different tissue types. There is the vascular tissue, that does not absorb much water. But also, cortex tissue, died off tissue from the flower, and the tissue with the fluffy hairs attached. Each absorbing different amounts of water, varying in how much they swell. And because they are all connected, change shape, when swelling. This makes the hairs to stick up straight.

You are picking another fluffy head, blow it clear, and watch the hundreds of fluffy seeds go. Searching for a fresh start. Searching for water. So, they can then fall to the ground, and grow into a yellow dandelion.

Literature

Madeleine Seale, Oleksandr Zhdanov, Cathal Cummins, Erika Kroll, Mike Blatt, Hossein Zare-Behtash, Angela Busse, Enrico Mastropaolo, Ignazio Maria Viola, and Naomi Nakayama (2020) Informed dispersal of the dandelion. bioRxiv 542696; doi: https://doi.org/10.1101/542696

Madeleine Seale, Annamaria Kiss, Simone Bovio, Ignazio Maria Viola, Enrico Mastropaolo, Arezki Boudaoud and Naomi Nakayama (2022) Dandelion pappus morphing is actuated by radially patterned material swelling. Nat Commun 13, 2498; doi: https://doi.org/10.1038/s41467-022-30245-3