Tuesday, 16 August 2011

Yellow snow.

In New Zealand, August is the month when pine pollen is dispersed on the wind.  Usually it’s best seen as a pale yellow tide mark around puddles.  But this week, we’ve had the lowest snowfall in Wellington for many years, with snow falling in the city and closing the airport for a while, and some of the snow is pale yellow with pollen.
In Karori, where I live (200 m altitude) we’ve had snow on the ground for a couple of days.  It came in three bursts, one on each of three successive days.  Although people in many parts of the world will wonder why this is even worth writing about, it’s been a source of great excitement here.  That’s because New Zealand’s climate is moderated by the surrounding oceans, and it’s rarely hot or cold.  Snow is rare at low altitudes in the North Island, and it’s 16 years since it last settled in our garden.  Here's snow falling at Victoria University of Wellington and in Kelburn, a nearby suburb.
Pollen grains are not single cells.  Pine pollen grains have four cells each at the time they’re shed.  Each is thus an independent multicellular organism, and it lives for about a year, so that this year’s pollen grains will spend the next year burrowing into the tissue of an ovule in a female cone, where one of their two sperms will fertilize an egg.  At least it will if it’s one of the very few lucky ones to be blown by chance onto the ovule of a female cone.  Otherwise, like 99.9999% of the grains, it’ll end up on the edge of a puddle, on a snow drift, or even forming a scum on the sea.
Pine pollen forming a scum at the beach, Monterosso del Mar, Italy, May 2006.

1 comment:

  1. Wow, across the road from where i live there has been yellow in the puddles? I thought it was a discharge of some sort? hopefully it's there tomorrow and i will take a photo of it. I think it's pollen? Now that you have told me about it. Thank you. Nice blog here.