Aster Dichotomous Key (Northeast US)

It is that time of year again!
Call me old school but learning from a field guide is still the best way to learn, and that goes double for asters. Between their similarities and the narrow window each year to learn in situ, I just do not have the skills needed to identify them on the spot, or think about which features to focus on.

Is there a good dichotomous key for Northeast aster species? Specifically Symphyotrichum species?

There is an excellent, but slightly out of date version I use for goldenrod species… this is along the lines of what I am looking for:

Thank you all!

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in the northeast, you can always go with the keys at the Native Plant Trust: or

for the entire US, you can use the Flora of North America key:, along with the species maps from BONAP: to narrow down species in the area.


Newcomb’s wildflower guide also has a good key for these. Definitely a worthwhile reference for other groups too.

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Yes I meant to mention the Newcomb’s guide… the one I have is out of date for this, and seems to leave out a level of detail for some species.

I would avoid the FNA key - it’s pretty out of date by now, and it’s a mess to try to navigate (mostly because of the wide scope). The character-states are not well delineated. It’s a headache to contemplate whether your flower head is truly “campanulate” or “cylindro-campanulate” and whether your plant of interest, invariably featuring a wide spectrum of leaf widths along a developmental gradient, in fact has leaves that are “narrowly lanceolate” or merely “lanceolate”.


Northeast of where?

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True of Asteraceae as a whole in the Flora of North America, unfortunately.

“The Northeast” in this context means northeastern United States.

Yes sorry Northeastern North America

Yes the Newcomb’s guide is out of date as well. The paintbrush stroke that is life on this planet how I see it, seems to go double for Asteraceae.

I get all fired up to go out and lock down some species but in the end I always feel a bit lost and uncertain no matter how many photos I take. The variety within a species amongst individuals is both incredibly frustrating and the beauty of the evolution.

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