Identifying and Differentiating Impatiens capensis and Impatiens pallida
In looking at field specimens, and reading monographs and identification books and sites, there are a number of characteristics that are suggestive of Impatiens capensis vs I. pallida. There does appear to be one characteristic that (at least based on everything I've observed thus far) may differentiate the two definitively, which is the observation by Justin Thomas from the Institute of Botanical Training, stating that:
On LARGER leaves of I. capensis, there are fewer teeth, typically no more than 9
On LARGER leaves of I. pallida, there are more teeth, typically over 9 up to 14.
I have put together a comparison table, along with the references I used, and stored it here: https://1drv.ms/u/s!AlrG7LkZ19f5kbcg_FDbsKuyp8N7dw?e=mxbCCq
My own observations are mostly from southern Michigan, and I welcome comments, additional characteristics, and especially if there are populations that don't follow the tooth number pattern.