i feel like with climate change on top of natural climate variability, in an area with tons of microclimates like Vermont’s mountains, it will rarely be possible unless you have the two growing together. Which they definitely sometimes do. But if they do intergrade, couldn’t phenology be an on-off gene that’s recessive or dominant, making the intermediates always go one way or another? They are distinct when they are distinct, but often not distinct, so they work well as subspecies. There are lots of things like that so i have a cery cynical view of ‘species inflation’.
I was in the field with two of Vermont’s best botanists. I found a ‘red or black spruce’ and asked them which one it was and neither of them could tell either. We conceded it was probably a hybrid. Every small swamp in Vermont seems to have one or two ‘kind of black spruce’ in the center of the wetland or tucked into an enclave sheltered from groundwater, on a sphagnum hummock. They look like and have characters of black spruce, but how would you have just one in so many wetlands? So I have to wonder if it isn’t just variable phenotype of red spruce. For sure in the black spruce swamps as you get further south away from the main range of black spruce, nearly all of the black spruce look like they are hybrids with red spruce, and sometimes full-on red spruce grows in the bogs in a stunted form instead of black spruce!
As for white spruce, in Vermont i usually can determine it immediately, but i got myself in trouble in coastal Maine where white spruce and red spruce look much more similar to each other for some reason.
Is this off topic? Am i gonna get the thread locked talking about Spruce in here or does that only apply to dandelions?