| 1 | Bracts and bracteoles conspicuous, forming an involucre. |
| 1' | Bracts and bracteoles inconspicuous (filiform or linear), or caducous before anthesis; no involucre. |
| 2 | Involucral bracts finely and deeply divided; plant densely glandular hairy; flowers 2½-5 cm ø; petals white; corona filaments ± purplish; fruit subglobose, c. 2 cm ø, yellow to orange; variable, a common weed; 0-1500 m. |
| 2' | Involucral bracts not divided. |
| 3 | Involucral bracts partially connate in a tube; flowers ± pinkish, with hypanthium 6-9 cm long. |
| 3' | Involucral bracts free or shortly connate at base; hypanthium less than 3(-4) cm. |
| 4 | Bracts to 4 cm, connate up to halfway; fruit ellipsoid, 7-12 cm, edible; ornamental and cultivated for the fruit; 500-2500 m. |
| 4' | Bracts to 5 cm, connate for ± ¾; fruit ellipsoid, to 6 cm; occasionally cultivated (closely related to, and hybridizing with P. mollissima); 500-2000 m |
| 5 | Flowers pink or red, pending on up to 20 cm long pedicels; hypanthium 2-4 cm; fruit ± fusiform, longitudinally ribbed, to c. 12 cm, edible; also cultivated as ornamental; New Guinea, locally running wild; c. 2000 m |
| 5' | Pedicels much shorter. |
| 6 | Leaves pinnately nerved, not lobed. |
| 6' | Leaves palmately nerved, mostly lobed or partite. |
| 7 | Stems 4-angular or -winged. |
| 7' | Stems not winged. |
| 8 | Petioles 6-glandular; stipules (lanceolate-) ovate, more than 1 cm wide; flowers 7-10 cm ø, purple-red; corona filaments banded, purple-white; fruit 12-30 cm long, edible; cultivated, sometimes escaped; to 1000 m. |
| 8' | Petioles 2-4-glandular; stipules lanceolate-linear, less than 1 cm wide; flowers 10-12 cm ø; corona filaments variegated with red, purple and white; fruit 8-10 cm long; occasionally cul tivated as an ornamental. See also P. X alato-coerulea LINDL., below; 0-1000 m. |
| 9 | Stipules thread-like, c. ½ cm; leaves ellipsoid to oblong, coriaceous; flowers c. 8 cm ø, flushed with purple or purple-dotted; corona filaments purple with white cross-bands; fruit ovoid, 5-8 cm long, edible; frequently cultivated, 0-1000 m |
| 9' | Stipules foliaceous; leaves herbaceous. |
| 10 | Glands on petiole thread-like or long-cavate; leaves deeply cordate; flowers 6-9 cm ø, white or pale pinkish; corona filaments banded; fruits ovoid, 6-8 cm long, edible; locally cultivated and escaped; 0-1000 m |
| 10' | Glands on petiole wart-like, sessile; leaf base ± cordate, rounded or acute. |
| 11 | Involucral bracts very large, extending beyond the flower, acute-acuminate; stipules lanceolate, longly acuminate, 1-1½ cm; flowers c. 10 cm ø, mottled purple-red; corona filaments banded; fruit c. 4 cm ø; ornamental, sometimes escaped; 0-1000 m. |
| 11' | Involucral bracts not extending beyond the flower, obtuse; stipules linear-subulate, 5-6 mm; flowers c. 10 cm ø, white and pinkish; corona filaments purplish banded; fruit globose, 3-6 cm ø; sometimes cultivated; 0-1000 m |
| 12 | Stipules lanceolate or filiform; involucral bracts serrate-denticulate. |
| 12' | Stipules foliaceous; involucral bracts(sub)entire. |
| 13 | Petiole with wart-like glands at apex; flowers 4-6 cm ø. |
| 13' | Glands at base of petiole; flowers c. 10 cm ø, red; plant ferruginous-tomentose; fruit ovoid, c. 5 cm long; 0-1000 m. |
| 14 | Plant glabrous; involucral bracts 1½-2 cm; petals white, corona filaments white with purple base; fruit ellipsoid, 4-6 cm long, purplish, sometimes yellow; cultivated and profusely escaped; 0-2000 m |
| 14' | Plant pilosulous; involucral bracts c. 1 cm; petals white or lavender, corona filaments mostly purplish or pinkish; fruit up to 5 cm ø; sometimes cultivated; c. 1500 m. |
| 15 | Stipules 1-2 cm long, falcate, mostly dentate. |
| 15' | Stipules large, 1½-4cm, straight, entire; flowers 4-5 cm wide, white; sepals ½-1 cm horned; fruit 2½-4 cm ø, with thick pericarp; ornamental and locally profusely escaped (India, Philippines, Queensland); 0-1000 m. |
| 16 | Glands on petiole wart-like, subsessile, c. 1 mm long; flowers white, lilac or purplish, 6-8 cm ø. |
| 16' | Glands on petiole filiform, 1-2 mm; flowers red, c. 6.8 cm ø; fruit not known; ornamental. |
| 17 | Leaves (3-)5(-9)-lobed, incisions nearly to the base; fruit ovoid to subglobose, c. 6 cm long; mostly ornamental; 0-2000 m. |
| 17' | Leaves 3-5-lobed, incisions to about ¾ of the blade. |
| 18 | Stem 4-angular; leaf 3-lobed, the lobes broad; Passiflora 'Impératrice Eugénie'; ornamental; 0-2000 m. |
| 18' | Stem terete; leaves 3-5-lobed, the lobes narrower; ornamental and escaped; 0-2000 m. |
| 19 | Flowers red, arranged in pending racemes; involucral bracts caducous before anthesis; flowersred, c. 7 cm ø; fruit narrowly ovoid, 5-7 cm; ornamental; 0-2000 m. |
| 19' | Flowers 1 or more in the axils of normal leaves; flowers greenish yellow or white, not red. |
| 20 | Flowers small, 1-1½ cm ø, apetalous, pale greenish; fruit a purple-black berry, 1-1¼ cm ø; variable, commonly established; 0-1500 m. |
| 20' | Flowers more than 1½ cm ø, provided with petals. |
| 21 | Leaves herbaceous, 2- or 3-lobed, not truncate. |
| 21' | Leaves ± coriaceous, 2-lobed or hemi-orbicular or obreniform, top truncate, lower surface with 2 rows of glands; flowers c. 3 cm ø; fruit globose, 1-2 cm ø; locally cultivated and escaped; 0-1000 m |
| 22 | Plant finely hairy. |
| 22' | Plant glabrous; leaves 3-lobed. |
| 23 | Flowers 1-2 per inflorescence; leaves 2-lobed; flowers 2-6 cm ø; fruit ± fusiform, hexagonal,5-6 cm; locally escaped in W. Java; 100-1000 m. |
| 23' | Flowers 4-8 per inflorescence; leaves 3-lobed. flowers 3-4 cm ø; fruit globose, c. 1½ cm ø(not yet observed in Old World specimens); occasionally cultivated; 0-1000 m. |
| 24 | Leaves variegated; lower surface with 2 large glands near the base of the midnerve; petiole without glands; flowers 3-4 cm ø; fruit c. 2 cm ø, glaucous; ornamental; 0-500 m. |
| 24' | Leaves not variegated, without glands at base of midrib; petiole with glands; flowers c.2½ cm ø; fruit subglobose, purple, c. 2½ cm long; occasionally cultivated; 0-1500 m. |
