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SUMMARY:Mechano-eco-evo of the Common Dandelion: What the Notorious Weed T
 ells Us About Plant Dispersal Strategies - Dr Naomi Nakayama\, Imperial Co
 llege London
DTSTART:20220224T130000Z
DTEND:20220224T140000Z
UID:TALK165094@talks.cam.ac.uk
CONTACT:Jake Harris
DESCRIPTION:Hairs\, whiskers\, stems… plants are made of slender cylinde
 rs of various scales. Why are they so prevalent? We have started to answer
  this question\, with an iconic example of hairy structures from nature: t
 he dandelion parachute. The parachute (botanically named pappus or plume) 
 is a bundle of about 100 filamentous organs\, which is positioned above th
 e seed. The pappus has over 90% empty space. Therefore\, the fluid dynamic
  mechanism of a parachute cannot apply to pappus\, and their flight mechan
 ism remained unknown.\nBy visualizing the air flow around the pappus in a 
 bespoke vertical wind tunnel\, we have found a previously unobserved type 
 of whirlwind (vortex). It is a ring-shaped vortex that is physically separ
 ated from the pappus but stays at a constant distance downstream of the bo
 dy. Such a separated vortex ring was first time to be observed\, and it is
  likely to help the seed stay afloat. The formation of the vortex ring is 
 dependent on the porous design of the pappus. Interestingly\, the pappus p
 orosity changes depending on the environment\; the pappus closes reversibl
 y depending on the moisture levels. In wet conditions\, the dandelion seed
 s don’t disperse as much. This may be a form of ‘informed dispersal’
  to tune their movement only when necessary. We then studied the mechanism
  behind the moisture-dependent morphing of the pappus\, focusing on the st
 ructure at the base of the pappus bristles.\n\nWith this example of the da
 ndelion diaspore\, I will illustrate how biomechanical investigation embed
 ded within the ecological context can provide new insights into key evolut
 ionary innovations in plant structures.\n\nContact reception@plantsci.cam.
 ac.uk for a Zoom link prior to a talk if you are not on our mailing list. 
 Due to having to go online\, we are restricting the talks to University of
  Cambridge and alumni to keep them as informal as possible.
LOCATION:Online
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