Here in the midwest, we’ve had a most un-spectacular fall as far as leaves changing colors is concerned. Usually, the rides through the country are just mind-boggling in their beauty. Yellow, orange, bright red, etc. But this year, blah. I understand that the most popular theories relate to our relatively dry summer and fall. But I also notice that some trees and bushes have undergone their normal bright, spectacular color change this autumn, but it’s only the smaller trees. Anything over about 12 - 15 feet went through a sort of green - greenish yellow - down kind of pattern. Why would the smaller plants have undergone such a dramatic change, but the large adult trees were so humdrum? Any botanists? horticulturists? gardeners? etc? any help?
We experienced the same thing here in the Northwest. Most of the trees are still clinging to their leaves. The only thing different this year is lack of moisture. The leaves just gradually went from green to pastel colors.
If you look at some of the many tree nurseries in the area, about half of the different varieties didn’t drop their leaves while the others did.
Has to be the lack of moisture, I guess the trees are holding on to the leaves to try and suck any remaining moisture out of them.
If we get any ice storms, imagine the damage.
The only exception I’ve seen (and a welcome one) is one kind of maple that got bright greenish yellow leaves. But it isn’t very widespread.
I’ve also seen one oak with deep reddish brown leaves, but it really isn’t showy.
ok, but why are the smaller trees apparently immune to the factors that have delimited the larger trees? Or are there other more compelling hypotheses?
Smaller trees are more susceptable to drought, so their leaves probably turned a little early this year. Here at least, we also had an early killing frost (mid 20’s) which, by killing the leaves, prevented the larger trees from turning color. If you prefer a more technical sounding explanation, you could always pin the whole thing on changes in Abscisic Acid production. It’s been too long since I studied botany for me to whip up a plausible scenario around this plant stress hormone, but I’m sure that someone else has already done it. All that’s needed is the right textbook.
I forgot to say that the maples I saw were all quite large, two stories or taller, not small.