1	Sterile lamina pinnate, most pinnae cuneate, rounded, truncate, or attenuate at base		(2)
+	Sterile lamina pinnate to pinnatifid or pinnatilobed, pinnae usually adnate to rachises		(5)
2 (1)	Sterile lamina glaucous abaxially.		2 P. glauca
+	Sterile lamina not glaucous abaxially		(3)
3 (2)	Aerophores on stipes and rachises elongate and hornlike with blunt apex.		1 P. pycnophylla
+	Aerophores on stipes and rachises cushionlike		(4)
4 (3)	Veins usually simple, or as many simple as forked.		3 P. euphlebia
+	Veins usually paired at base or forked above base.		4 P. japonica
5 (1)	Sterile lamina glaucous abaxially.		5 P. assurgens
+	Sterile lamina not glaucous abaxially		(6)
6 (5)	Rachises of sterile lamina abaxially semiterete to trigonous.		6 P. adnata
+	Rachises of sterile lamina abaxially carinate or flattened		(7)
7 (6)	Stipes distally tetragonal in cross section.		7 P. stenoptera
+	Stipes distally triangular in cross section.		8 P. falcata