Mentzelia montana

According to Brokaw's treatment in FNA (2016, vol. 12), " Mentzelia montana is widely distributed and, in portions of its range, difficult to distinguish from M. albicaulis. Mentzelia montana is morphologically intermediate to M. albicaulis and M. congesta, but ecologically more similar to M. congesta (J. M. Brokaw 2009). Mentzelia montana generally occurs at higher elevations than M. albicaulis and is best distinguished morphologically from M. albicaulis by capsule and bract characteristics. Capsules of M. montana are usually not longer than 17 millimeters or curved more than 45°, whereas those of M. albicaulis are often longer and more curved. Both species may have bracts with some lobes and whitish base, but only M. montana has populations in which these features are prominent. Sepal and petal lengths, which have sometimes been used to distinguish these species, overlap completely."