Springing into summer

What a difference a couple of weeks makes in woodland at this time of year. A fortnight ago the trees in High wood were just bursting into acid green leaf and the ground was a carpet of blue. The bluebells were taking full advantage of the dappled light beneath the patchy canopy.

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Now the canopy has filled out and the quality of light beneath has changed completely, even on the edge of the woodland where my sycamore resides.

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The bluebells have grown pale and lanky and are starting to set seed, making the most of the remaining light to complete their life cycle.

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Of course it should be no surprise to me that it feels so different under the tree canopy now. After all, the job of tree leaves is to arrange themselves so as to intercept as much light as possible for photosynthesis. Leaves not only absorb a lot of light but, in addition, are selective about the wavelengths absorbed. More than 99 percent of the red and blue light wavelengths used for photosynthesis (known as Photosynthetically Active Radiation – PAR) are absorbed as light passes through a dense tree canopy. Leaves appear green to us only because this wavelength is largely reflected, rather than absorbed, by leaves.

It is also easy, now, to see why there were so many oak leaves under my sycamore tree in the winter – several of the trees around it on the edges of the woodland are young oaks.

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The undergrowth on the fringes of the woodland is also growing fast – next time I’ll be wearing shoes which cover my feet properly!

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When I braved the nettles and got close enough to photograph some of the pendulous flower spikes I could see that what, at first, look like tiny petals are actually clusters of pollen-bearing anthers – the curly stigma protrudes from the midst of these in the oldest flowers in each spike.

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Flower spike and individual flower of sycamore, Acer pseudoplatanus

Some of the flowers were also providing a late breakfast for resident wildlife, reinforcing my point (see My sycamore tree) about the value of sycamores in our woodlands.

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One comment

  1. […] There are all kinds of reasons why plants which flower early might want to rely more on vegetative spread than on seed production – there are fewer insects around for pollination early in the year; the plant is getting less energy from the sun because light intensity is limited; temperatures are lower so all the reactions needed for growth take place more slowly.  Although we grow many of these species in our parks and gardens for spring colour, their natural habitat is often on a woodland floor where rapid completion of the growth cycle is necessary before the trees above completely block their light.  I thought about this a lot in 2016 when I followed the progress of a sycamore tree and its understorey through the year. […]

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