For instance, at the beginning of the video she tries spacing the leaves at 180 degrees, so the second leaf is on the opposite side of the stem, then the third leaf is over the first leaf, but in the drawing, there is a lot of vertical space between the leaves and given the varying height of the sun across a day, this arrangement might give each leaf more sunlight across a day rather than an arrangement where a leaf gets sunlight, say, only in the morning. Does this spiral arrangement actually maximize the amount of sunlight each leaf gets across a period of a day? Would the optimal arrangement of leaves depend upon the latitude that the plant grows in? Is the spiral arrangement optimal given a random latitude for the plant?
According to wikipedia ( http://en.wikipedia.org/wiki/Phyllotaxis ) the arrangement of leaves is largely dependent upon the distribution of auxin:
The pattern of leaves on a plant is ultimately controlled by the local depletion of the plant hormone auxin in certain areas of the meristem.[3] Leaves become initiated in localized areas where auxin is absent. When a leaf is initiated and begins development, auxin begins to flow towards it, thus depleting auxin from another area on the meristem where a new leaf is to be initiated. This gives rise to a self-propagating system that is ultimately controlled by the ebb and flow of auxin in different regions of the meristematic topography.[4]
Why would that lead to a spiral pattern of leaves? That seems more likely to lead to the 180 degree pattern.
Interesting video. I wish I had time to look into this a little bit more.
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