The dandelionROEN
A dandelion seed head against the light in a green meadow.

  1. A flower, a breath, the wind

    The dandelion: how far its seeds fly, and why they float

    A dandelion’s white seed head carries about 150 seeds. Press and hold the flower to blow, or blow into your microphone: each seed leaves in the wind that is blowing where you are right now, and comes down where a published model of seed flight sends it.

    Blow, then read on

  2. After you blow

    Most land close by. A few go far#

    In the model on this page, held to your lips at 1.5 m, in a breeze of 4 m/s (measured 10 m up), a dandelion drops half its seeds within 5.0 m and only 12% within two metres; about one in 50,000 passes 100 metres. Left on its stalk, 35 cm above the ground, it keeps its seeds close: half land within 39 cm.

    Every blow is a fresh draw. Blow again and the seeds fall differently, as they would in a real meadow.

  3. Why it floats

    A parachute made mostly of gaps#

    Each seed hangs beneath a crown of about 100 hairs, 13.8 mm across. Seen from above, the crown leaves 92% of its enclosing circle empty. The air passing between the hairs holds a small, steady ring of swirling air just above the crown, and that ring brakes the fall: in still air a seed sinks only 39 cm a second. How the ring of air works.

    100hairs in a crown
    13.8 mmacross the crown
    39 cm/sfalling speed in still air
    0.63 mgwhat one seed weighs

    Let go from a flower 35 cm tall, a seed would touch the ground in 0.9 seconds if the air stood still. In that time a breeze of 4 m/s (measured 10 m up; down among the grass it blows more slowly) carries it about 0.5 m. That is why most land close by. The ones that travel far are those an eddy lifts before they touch down.

  4. When the air turns wet

    In rain or mist, the crowns close and the seeds hold on#

    Wet a dandelion seed and its crown closes like an umbrella: the angle between its outermost hairs narrows by 60 to 90 degrees. It keeps closing while wet and for 5 to 15 minutes after. A tissue at the base of the crown does the work: it swells when it gets wet.

    After an hour in the wet, fully closed seeds fall 2 to 3 times faster. They also come loose less easily: in a wind tunnel, at the strongest wind tried (9.8 m/s), three in four dry seeds came loose but only half the wet ones. Adding the winds of wet and dry hours in Edinburgh, the authors estimate a wet seed leaves the plant 8 times less often. So seeds leave mostly in dry weather, which in their records is also windier; they think the closing may have evolved for that.

  5. What comes up

    In most dandelions, every seed is a copy of the mother plant#

    Most common dandelions, over most of their range, make seeds without being pollinated. The flower still opens, and often makes plenty of pollen, but each seed forms from the mother plant alone, so every seed carries her genes almost unchanged, apart from rare mutations. Botanists call this apomixis: cloning through seeds. Dandelions that breed this way are spread over a wider area than their relatives that need pollen.

    Some dandelions breed only by cross-pollination, and their seeds differ from one another. Such plants grow in central Europe, for instance in the Pannonian region; they carry fewer sets of chromosomes than the cloning kind. Now and then, pollen from a cloning dandelion lands on one of them, and some of the offspring can become new clones.

  6. What decides the distance

    The wind matters, and so does how high the flower is#

    Each dot is ten seeds out of 2,000, piled where the model sends them. Change the wind or lift the flower.

    The model here treats the eddies of ordinary wind as an average spread. It leaves out the warm air that rises off the ground on sunny days and the gusts that tear seeds loose. Long flights cannot be tracked in the field, and the models disagree widely. One that includes rising warm air found that more than one seed in 2,000 passes 100 metres, and that strong wind does not help them go far; in this page’s model, by contrast, stronger wind does send more seeds far. A detailed simulation that follows the eddies one by one through Edinburgh’s dry-weather winds, and lets seeds come loose mostly in strong gusts, as in the wind tunnel, put half the seeds beyond 4.3 m for a flower at 35 cm, more than ten times further than this page’s model at 4 m/s, and sent about one in six of the seeds that came loose beyond 100 metres. Its authors write that its longest flights cannot be checked against reality.

  7. Next time

    How to send the seeds furthest#

    Pick a dandelion on a dry day, when the crowns are fully open. Hold it up before you blow: in this page’s model, in the same breeze, the distance within which half the seeds land is 13 times greater for a flower held at 1.5 m than for one left at 35 cm, and between 8 and 18 times depending on the grass height and the turbulence formula. The simulation in which gusts tear seeds loose carries even the 35 cm flower far, so there the gain would be smaller. And blow with the wind at your back.

    Whatever you do, most will land within a few metres and, if it is a cloning dandelion like most, they will be copies of the plant you picked.

Lion’s tooth, priest’s wife, clock: the dandelion’s names#

The English name comes from Old French dent de lion, “lion’s tooth”, through Middle English dent-de-lioun, after the toothed leaves; it appears in English in the late 14th century. Romanians call the plant păpădie: the standard Romanian dictionary (DEX) derives it from Bulgarian popadija, while Ciorănescu’s etymological dictionary links it to Greek papadiá, “the priest’s wife”.

In Britain a dandelion in seed is a “dandelion clock”. The Scottish National Dictionary records “clocks” for dandelions in seed, citing an 1880 glossary of Antrim and Down, and explains the name by the children’s custom of blowing on the seed head to tell the time.

How the page works out the seeds’ flight#

Each seed that comes loose gets a distance drawn at random from the WALD model (Katul and colleagues, 2005). The model starts from the height the seed leaves from, its falling speed in still air (0.391 m/s, measured by Cummins and colleagues on ten seeds), the mean wind between the ground and that height, and the turbulence of the air above the grass (formulas from Zhu and colleagues, 2021). The distance is a random draw, not a forecast.

The wind right now comes from Open-Meteo, for the place your device’s time zone points to (or your exact place, if you give it), rounded to a tenth of a degree. It is the wind 10 m up; the page brings it down to the flower’s height with the logarithmic wind profile over grass 20 cm tall, as Seale and colleagues assumed. The flower on its stalk sits at 35 cm, the height Seale and colleagues used; the flower held in a hand sits at 1.5 m, about where a standing adult’s mouth is. The head on screen has 150 seeds, the average of the 20 heads Seale and colleagues counted; study averages run from about 60 to 250 seeds a head, and single heads have held up to 412.

The path drawn for each seed is one of the random paths the model allows for a seed that lands exactly there; the landing spot comes from the model, the heights along the way are illustrative. Drift towards or away from the viewer is not shown: the scene is seen from the side, across the wind. Time is sped up when flights are long. The head closing in rain takes minutes in reality, a few seconds on screen.

Sources#

  • Cummins, C. et al. (2018). A separated vortex ring underlies the flight of the dandelion. Nature 562: 414–418. doi.org
  • Seale, M. et al. (2022). Environmental morphing enables informed dispersal of the dandelion diaspore. eLife 11: e81962. doi.org
  • Seale, M. et al. (2022). Dandelion pappus morphing is actuated by radially patterned material swelling. Nature Communications 13: 2498. doi.org
  • Katul, G. G. et al. (2005). Mechanistic analytical models for long-distance seed dispersal by wind. The American Naturalist 166: 368–381. doi.org
  • Nathan, R. et al. (2011). Mechanistic models of seed dispersal by wind. Theoretical Ecology 4: 113–132. doi.org
  • Zhu, J. et al. (2021). Seed dispersal by wind decreases when plants are water-stressed, potentially counteracting species coexistence and niche evolution. Ecology and Evolution 11: 16239–16249 (supporting information, the WALD model). doi.org
  • Bullock, J. M. et al. (2012). Modelling spread of British wind-dispersed plants under future wind speeds in a changing climate. Journal of Ecology 100: 104–115. doi.org
  • Tackenberg, O., Poschlod, P. & Kahmen, S. (2003). Dandelion seed dispersal: the horizontal wind speed does not matter for long-distance dispersal — it is updraft! Plant Biology 5: 451–454. doi.org
  • Soons, M. B. et al. (2004). Determinants of long-distance seed dispersal by wind in grasslands. Ecology 85: 3056–3068. doi.org
  • Stewart-Wade, S. M. et al. (2002). The biology of Canadian weeds. 117. Taraxacum officinale. Canadian Journal of Plant Science 82: 825–853 (seeds per head). doi.org
  • Majeský, Ľ. et al. (2012). The pattern of genetic variability in apomictic clones of Taraxacum officinale. PLoS ONE 7: e41868. doi.org
  • van Dijk, P. J. (2003). Ecological and evolutionary opportunities of apomixis: insights from Taraxacum and Chondrilla. Philosophical Transactions of the Royal Society B 358: 1113–1121. doi.org
  • Mártonfiová, L. (2011). Comparison of breeding behaviour of Taraxacum sect. Ruderalia and Taraxacum sect. Erythrosperma. upjs.sk
  • Dexonline: “păpădie” (DEX ’09, DER). dexonline.ro
  • Online Etymology Dictionary: “dandelion”. etymonline.com
  • Scottish National Dictionary: “clocks”. dsl.ac.uk
  • Open-Meteo: current wind, humidity and precipitation. open-meteo.com

More on the site: The dandelion and the ring of air · The spiders that fly · How long does a seed live?