1. Staminodium (flattened, expanded structure along the upper part of the floral tube) greenish or yellowish, the free apex usually distinctly broader than long; mature capsules (5-) 6-9 mm long; larger leaf blades truncate to rounded at base, never cordate.
1. Staminodium dark brown or purple (very rarely green), the free apex scarcely if at all broader than long; mature capsules 4-6 (-7) mm long; larger leaf blades often cordate.
Citation:
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. March 16, 2025
https://mifloradev.lsa.umich.edu/flora-demo/#/genus/Scrophularia