I was curious about the white pine branch after finding a second 6-needled fascicle on it. I had my tiny field assistant drag the branch in question back home to our lab. I pulled off each of the fascicles from the most recent growth of the branch (about 10″ long) and separated the fascicles by how many needles they had (see table below). Of the 170 fascicles, 51 (30%) had more than 5 needles!! There were two notable features about the branch (besides the anomalous number of needles per fascicle):
- The tip of the branch was exceptionally stout, over 1/2″ in diameter
- The branch had come from the top of the canopy
As I counted each fascicle, a clear pattern emerged: fascicles towards the tip of the branch were more likely to have more than 5 needles. It’s hard to say why exactly this pattern exists (and as with last week’s newsletter, there really isn’t much research on the topic). Wikipedia says that Scots pine, which typically have 2 needles per fascicle, can have 3 or 4 on stout branches, though it doesn’t cite a source for this or explain why.
White pine fascicle with just 2 needles
White pine fascicle with 8 (yes, 8!!) needles