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1 Petioles with a distinct joint about 1-3 cm above the base, the petiole bases of former leaves forming a fairly even stubble; leaf blade lacking glands (though bearing both long septate hairs and pale linear scales); indusium of numerous filamentous segments; [subgenus Woodsia or genus Woodsia subgenus Woodsia (Lu et al 2020) or genus Woodsia (Shmakov2015)]
1 Petioles lacking a joint, the petiole bases of former leaves disintegrating irregularly and forming an uneven stubble; leaf blade with stalked glands, at least below on the costae, costules, and veins (and also bearing nonglandular hairs and/or linear scales); indusium of 3-6 lanceolate segments.
..2 Rachis with flattened, septate, white hairs and elongate stipitate glands; leaf blade with flattened, septate, white hairs and elongate stipitate glands; [subgenus Physematium, or genus Physematium subgenus Physematium (Lu et al. 2020), or genus Physematium (Shmakov 2015)]
..2 Rachis with scattered scales; leaf blade with sparse to dense stipitate glands; [subgenus Physematium, or genus Physematium subgenus Woodsiopsis (Lu et al. 2020) or genus Woodsiopsis (Shmakov 2015)].
....3 Spores averaging 42-47 µm; proximal pinnules of lower pinnae usually shallowly lobed or merely dentate; blades coarsely cut and evidently 2-pinnate; rhizomes compact to short-creeping, individual branches usually 5-10 mm in diameter; [widespread in our area]
....3 Spores averaging 35-42 µm; proximal pinnules of lower pinnae usually deeply lobed or pinnatifid; blades finely cut, 2-pinnate-pinnatifid; rhizomes short- to long-creeping, individual branches 3-5 mm in diameter; [Ozarkian/Texan, as far as known]