| 1 | Cross section of stems with a central vascular cylinder, surrounded by three (sometimes only one) peripheral cylinders disposed in a triangular arrangement |
| 1' | Cross section of stems with a single vascular cylinder |
| 2 | Inflorescence cauliflorous, fascicled, produced on mature, leaf-less stems |
| 2' | Inflorescence axillary or distal, produced on leafy branches, solitary or fascicled |
| 3 | Petiole and leaf rachis winged; capsules unwinged; |
| 3' | Petiole and leaf rachis unwinged; capsules winged |
| 4 | Inflorescence fascicled; capsules winged |
| 4' | Inflorescence solitary; capsules unwinged |
| 5 | Plant pubescent; stipules 7-15 mm long; capsule globose or globose-trigonous |
| 5' | Plant glabrous or puberulent; stipules < 7 mm long, capsule pyriform |
| 6 | Petiole and leaf rachis unwinged or margined |
| 6' | Petiole and leaf rachis winged |
| 7 | Leaves 7-11-foliolate pinnate |
| 7' | Leaves 5-foliolate pinnate, trifoliolate or biternate |
| 8 | Stipules < 5 mm long |
| 8' | Stipules > 1 cm long |
| 9 | Fruit winged; inflorescence fasciculate |
| 9' | Fruit unwinged; inflorescence solitary |
| 10 | Leaves biternate |
| 10' | Leaves 5-foliolate pinnate or trifoliolate |
| 11 | Leaflets acuminate at apex; capsules winged; plant tomentose or tomentulose |
| 11' | Leaflets ligulate at apex; margins bidentate at apex; capsules unwinged; plant tomentulose or puberulent |
| 12 | Leaves trifoliolate |
| 12' | Leaves 5-foliolate pinnate |
| 13 | Leaflets abaxially flavo-sericeous-tomentose; capsules unwinged |
| 13' | Leaflets abaxially glabrous or barbate at vein angles; capsules winged (or unknown in P. anomophylla) |
| 14 | Leaflets glabrous; petioles terete |
| 14' | Leaflets abaxially barbate or barbulate; petioles margined |
| 15 | Fruit 9-winged (very short wings) or verrucose |
| 15' | Fruit 3-winged |
| 16 | Calyx and capsules cinereus-sericeous, with 9 distal, short, divaricate wings |
| 16' | Calyx and capsules ferruginous, hirto-tomentose, with 9 longitudinal, wrinkled ridges |
| 17 | Leaf rachis unwinged |
| 17' | Leaf rachis winged or margined |
| 18 | Leaflets lustrous on both surfaces, with entire, or remotely subdentate margins; tertiary venation clathrate |
| 18' | Leaflets not lustrous, or if so only on adaxial surface, margins variously serrate or dentate; tertiary venation clathrate, subclathrate, or reticulate |
| 19 | Capsules winged or triquetrous (narrowly winged) |
| 19' | Capsules unwinged (globose, ellipsoid or pyriform) |
| 20 | Plant puberulent or glabrous |
| 20' | Plant pubescent, hispidulose, tomentose or setose (at least the young parts) |
| 21 | Capsules ferruginous-tomentulose, with wing surrounding the coccus and slightly projecting beyond its apex and tapering on the stipe; seeds puberulent |
| 21' | Capsule glabrous, with dorsal, distal wings slightly projecting beyond the apex; seed glabrous |
| 22 | Plant setose; stipules deeply dissected, to 1.5 cm long |
| 22' | Plant pubescent hispidulose, or tomentose; stipules minute, not dissected |
| 23 | Leaflets obtusely acuminate at apex, capsules 2.5-3 cm long, the wings projecting beyond the apex, running through the lenght of the locule and tappering at base into an elongated stipe |
| 23' | Leaflets acuminate at apex; capsules otherwise |
| 24 | Leaflets abaxially puberulous or glabrous, with subentire margins |
| 24' | Leaflets abaxially ferruginous or flavo tomentose, with repando-dentate margins |
| 25 | Capsule with narrow, lengthwise dorsal wings |
| 25' | Capsule wings on distal portion of locule, elongated, divaricate |
| 26 | Leaflets (chartaceous to coriaceous ac.desc.) coriaceous, abaxially ferruginous-sericeous, with serrate margins; inflorescence axillary racemiform |
| 26' | Leaflets chartaceous, abaxially pubescent, with remotely dentate margins; inflorescence cauliflorous, fascicled |
| 27 | Body of fruit (locule) globose or ellipsoid, 8-10 mm long |
| 27' | Body of fruit (locule) clavate, ca. 20 mm long |
| 28 | Stems 4-5-costate; stipules dissected |
| 28' | Stems terete, nearly terete or triangular; stipules entire or inconspicuous |
| 29 | Stems hirsute-tomentose; stipules 1.5-2 cm long; bracteoles ca. 4 mm long, overlapping; cincinni congested along inflorescence rachis |
| 29' | Stems tomentulose, puberulent or glabrescent; stipules 2-4 mm long; bracteoles ca. 1 mm long, not overlapping; cincinni spaced out along inflorescence rachis |
| 30 | Plant glabrous |
| 30' | Plant puberulent, tomentose, hirsute-tomentose, or hirsute |
| 31 | Capsules with 9 longitudinal wrinkled ridges |
| 31' | Capsules without ridges or with 6 longitudinal, smooth ridges |
| 32 | Leaflets with clathrate tertiary veins |
| 32' | Leaflets with reticulate tertiary veins |
| 33 | Leaflet margins entire for most part, sometimes with a few teeth near the base or near the apex |
| 33' | Leaflet margins serrate or remotely glandular serrate |
| 34 | Capsule depressed-globose or globose-trigonous, minutely pubescent or glabrous, woody-crustose, wrinkled when dried |
| 34' | Capsules ellipsoid, unwinged, 6-costate, sericeous-pubescent |
| 35 | Capsule obovoid, globose, ovoid, or ellipsoid, slightly chartaceous, 6-ridged, ferruginous-tomentose, long-stipitate |
| 35' | Capsules, globose, smooth, crustose, (drying wrinkled) glabrous, shortly stipitate |
| 36 | Plant glabrous; capsule nearly globose, glabrous, coriaceous, with 6 longitudinal sulci, 1.2-1.5 × 1.2-1.5 cm; mesocarp ca. 1 mm thick; endocarp glabrous; seed one per fruit. |
| 36' | Plant tomentose, becoming glabrous; capsule obovoid to depressed-globose, sericeous-tomentose, slightly rugose, 3-3.5 × 3-3.7 cm; mesocarp ca. 3 mm thick, endocarp puberulent; seed (1) 2 per fruit |
| 37 | Fruit winged |
| 37' | Fruit not winged |
| 38 | Stem trigonous to subterete; leaflets abaxially glabrous or puberulent, with minute dark papillae, the margins not ciliate; capsule wing surrounding most part of coccus |
| 38' | Stem terete; leaflets abaxially pilose along midvein, the margins ciliate; fruit wings on upper half of coccus ascending or slightly divaricate |
| 39 | Capsule ferruginous-tomentose |
| 39' | Capsules glabrous |
| 40 | Capsules crustose, drying wrinkled |
| 40' | Capsules woody or coriaceous |
| 41 | Capsules nearly globose, long stipitate; leaflets with minute hairy domatia at the secondary veins axils on abaxial surface |
| 41' | Capsules pyriform; leaflets without domacia |
| 42 | Bracts oblong, 7-10(15) mm long; stipules 2-4.5(7) cm long |
| 42' | Bracts subulate, 1-3 mm long; stipules 0.5-1(2.5) cm long |
| 43 | Stipules 0.5-1 (2.5) cm long; petiolules of lower pair of leaflets ca. 0.5 cm long; pericarp ca. 1 mm thick |
| 43' | Stipules ca. 0.5 mm long; petiolules of lower pairs of leaflets 2-2.5 long; pericarp ca. 4 mm thick |
