[HN Gopher] Length and thickness of bamboo internodes: a beautif...
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       Length and thickness of bamboo internodes: a beautiful curve
        
       Author : elsewhen
       Score  : 40 points
       Date   : 2024-04-23 19:27 UTC (1 days ago)
        
 (HTM) web link (www.elegantexperiments.net)
 (TXT) w3m dump (www.elegantexperiments.net)
        
       | blovescoffee wrote:
       | Following negative exponential growth towards the top makes some
       | sense. You want to have more weight towards the bottom/middle for
       | balance. Interesting that the bulk is in the middle of the stalk.
       | 
       | edit: Maybe I misunderstood? I'm a bit confused on width/length
       | here.
        
         | soneca wrote:
         | "Wall thickness" (not width) decreases from bottom to top,
         | which fits your comment of more weight towards the bottom.
         | 
         | Internode length increases up to the middle node (not sure if
         | it's also middle height), then decreases from mid-node to top.
         | 
         | Then internodes at the top are shorter and lighter.
         | 
         | I don't know if the length pattern has some evolutionary
         | advantage.
        
       | 123pie123 wrote:
       | the first thing that came to mind was it looks like the curve of
       | a charging then discharging of a capaciter in a RC circuit
        
         | mhuffman wrote:
         | It looks like a type of beta pdf distribution curve to me.
         | Interesting!
        
         | diydsp wrote:
         | yes definitely transitions from
         | 
         | y(t) = V * [ 1 - e^(-R * C * t) ]
         | 
         | to
         | 
         | y(t) = V * e^[-R * C * (t-T) ]
         | 
         | since the weight of the plant is cumulative, it's interesting
         | to think about the integral of these functions as they hold up
         | the plant.
        
           | mitthrowaway2 wrote:
           | Maybe even the double-integral, since the plotted variable is
           | node-number, not length. Integrating once would give node
           | length as a function of height along the stalk, and then
           | integrating a second time (times wall thickness) would give
           | weight.
        
       | mtippett wrote:
       | The following could be completely wrong...
       | 
       | Bamboo is a grass, it doesn't layer bark. It's one and done. The
       | internode distance is pretty much fixed once it hardens. The
       | bamboo cells inflate and harden. So the graphs make a reasonable
       | amount of sense.
       | 
       | The wall thickness is a function of time to harden, and time to
       | add extra stuff to the wall. Segments close to the ground have
       | simply longer time, and likely hardening begets hardening.
       | 
       | The internode distance is interesting in that there is a natural
       | point at which the bamboo stops elongating and begins to start
       | shortening (again in a negative exponential). My understanding is
       | that bamboo does start to keep "leaves" that sprout from the
       | nodes, to gather light and energy. I wonder if that is the point
       | that the leaves start, and hence it is a mixture of both time
       | (less time = shorter) and investment in energy (effort to grow
       | sun-catching leaves).
       | 
       | Some interesting followups would be in the natural habitat, where
       | does the typical canopy start?
        
       | ggm wrote:
       | D'Arcy Thompson: On Growth and Form. (1917)
       | 
       | https://en.wikipedia.org/wiki/D%27Arcy_Wentworth_Thompson#On...
        
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       (page generated 2024-04-24 23:00 UTC)