1	Each new young shoot developing from near apex of last developed pseudobulb: stems consisting of superposed pseudobulbs (P. sect. Articulatae (H. G. Reichenbach) Pfitzer).		1 P. articulata
+	Each new young shoot sprouting from base of a pseudobulb (usually last developed one): pseudobulbs arranged along a usually short to very short rhizome		(2)
2 (1)	Rhizome pendulous, only at base attached to substratum by roots; aerial roots often present on pendulous part of rhizome; pseudobulbs turned to all sides of rhizome; inflorescences generally hysteranthous, each borne on a shoot not developing into a leaf-bearing pseudobulb after anthesis (P. sect. Crinonia (Blume) Butzin).		2 P. protracta
+	Rhizome creeping, along most of its length attached to substratum by roots; aerial roots absent; pseudobulbs turned to one side of rhizome; inflorescences synanthous or proteranthous		(3)
3 (2)	Pseudobulbs 1-leaved (P. sect. Pholidota)		(4)
+	Pseudobulbs 2-leaved		(5)
4 (3)	Mature leaves thick, leathery; floral bracts with numerous dense fine veins; lateral sepals free at base.		3 P. imbricata
+	Mature leaves thin, herbaceous; floral bracts with less than 25 relatively coarse veins; lateral sepals connate at base.		4 P. pallida
5 (3)	Pseudobulbs crowded to ca. 2.5 cm apart on rhizome; floral bracts persistent at anthesis (caducous in P. leveilleana); keels on lip hypochile absent or low and swollen; keels on epichile, if present, at most 2 (P. sect. Chinenses (H. G. Reichenbach) de Vogel)		(6)
+	Pseudobulbs rather widely spaced along rhizome; floral bracts caducous at anthesis, usually falling off but sometimes remaining clasped around flower; base of lip hypochile smooth (P. sect. Repentes de Vogel)		(9)
6 (5)	Petals ca. equally wide as or only slightly narrower than dorsal sepal		(7)
+	Petals less than 1/2 as wide as dorsal sepal (see note under P. chinensis)		(8)
7 (6)	Floral bracts persistent during anthesis; pseudobulbs very slender, fusiform; petals more than 7.5 mm.		5 P. roseans
+	Floral bracts caducous at anthesis; pseudobulbs swollen, ovoid; petals less than 5.5 mm.		6 P. leveilleana
8 (6)	Pseudobulbs usually 1.6-8 × 0.5-2.3 cm, narrowly ovoid-oblong, contracted into a short stalk at base; lip hypochile with 3 basal swollen veins, epichile usually unornamented; leaves ± turning black when dry.		7 P. chinensis
+	Pseudobulbs 4-11.5 × 0.3-0.4 cm, subcylindric, not narrowed into a short stalk at base; lip hypochile with 2 basal lamellae, epichile 3-ridged; leaves not turning black when dry.		8 P. longipes
9 (5)	Lip almost entirely saccate, with a small lateral depression on each side at base; epichile very small		(10)
+	Lip consisting of a broad saccate hypochile without lateral depressions and a broad epichile suborbicular in outline when flattened		(11)
10 (9)	Plants sturdy; flowers opening widely; hypochile with 3 keels at back which are fused at base; column apical hood relatively large, with a rounded top; anther cap inserted ca. halfway between stigma and hood margin; epichile consisting of 2 small lobes that are bent over front opening of hypochile, rarely lobes reduced or absent.		9 P. convallariae
+	Plants rather small; flowers not opening widely; keels absent; column apical hood abruptly truncate; anther cap inserted on top margin; epichile consisting of a triangular to narrowly triangular concave point.		10 P. cantonensis
11 (9)	Roots rather sturdy, "woody," stiff, 1.5-2 mm in diam.; epichile abruptly recurved giving lip a distinctly sigmoid appearance, ecallose, 2.8-4 mm.		11 P. yunnanensis
+	Roots rather slender and flexuous, herbaceous, 0.5-1 mm in diam.; lip not distinctly curved; hypochile with 3 short keels at back; epichile 1-2 mm.		12 P. missionariorum