As leaves are just starting to color up, the question is, “Will the autumn leaf show be good this year?” First off, whether or not it’s good, global warming has pushed showtime forward a bit each year. Around here, the peak of the show used to be the middle of October; nowadays it’s the third week in October.
Back to predicting how good the show will be this year . . . Throughout summer and into autumn most leaves are, of course, green, which is from chlorophyll. Chlorophyll must be continually synthesized for a leaf to stay green. The shorter days and lowering sun of waning summer are what trigger leaves to stop producing it, letting other pigments lurking there out of hiding.
The yellow and orange colors of leaves are always lurking there, thanks to carotenoid pigments, which help chlorophyll do its job of harvesting sunlight …