| 1 | Plants herbaceous or suffrutescent |
| 1' | Plants woody |
| 2 | Plants branched; sap watery |
| 2' | Plants monocaul and subacaul; sap milky |
| 3 | Plants armed with thorns |
| 3' | Plants unarmed |
| 4 | Staminate and pistillate inflorescences globose-capitate; stamens straight in the bud |
| 4' | Staminate inflorescences spicate, racemose or capitate and stamens inflexed in the bud; pistillate inflorescences with 1-3 flowers |
| 5 | Inflorescences urceolate and stigmas and anthers not exposed at anthesis; waxy glandular spots on the lamina lower surface (at the base of the midrib, in the axils of lateral veins and/or furcations of lateral veins), or on the nodes of leafy twigs |
| 5' | Inflorescences not urceolate and stigmas and anthers exposed at anthesis; waxy glandular spots mostly lacking, but present on the lamina beneath in the axils of lateral veins only in Artocarpus subg. Pseudojaca |
| 6 | Stipules fully amplexicaul |
| 6' | Stipules not fully amplexicaul to lateral |
| 7 | Stipules connate |
| 7' | Stipules free |
| 8 | Leaves of lateral (flower-bearing) branches spirally arranged (or subopposite) |
| 8' | Leaves of lateral (flower-bearing) branches distichous |
| 9 | Stipules connate |
| 9' | Stipules free |
| 10 | Pistillate flowers connate; staminate flowers with 1 stamen |
| 10' | Pistillate flowers free; staminate flowers with 2-4 stamens |
| 11 | Inflorescences discoid- to turbinate-capitate with marginal bracts |
| 11' | Inflorescences spicate or globose-capitate |
| 12 | Lamina with 3 or 4 pairs of lateral veins (S. ascendens) |
| 12' | Lamina with 5-9 pairs of lateral veins (B. papyrifera) |
| 13 | Inflorescences bisexual |
| 13' | Inflorescences unisexual |
| 14 | Inflorescences cymose; perianth of the pistillate flower tubular |
| 14' | Inflorescences spicate; perianth of the pistillate flower with free imbricate tepals (S. elongatus) |
| 15 | Inflorescences discoid-capitate or uniflorous, involucrate with basally attached imbricate bracts, or bracts concentrated in the upper part of the receptacle of the pistillate inflorescence with a single flower adnate to the receptacle |
| 15' | Inflorescences globose-capitate, spicate, racemose, cymose, or if uniflorous, then not involucrate |
| 16 | Receptacle of the pistillate inflorescence infundibuliform, enclosing and fused with a single flower; involucral bracts small and partly scattered on the receptacle; staminate inflorescences usually several together |
| 16' | Receptacle of the pistillate inflorescence discoid, the flower(s) free and the involucral bracts large, in 4 or 5 rows imbricate; staminate inflorescences solitary |
| 17 | Scaled axillary resting buds present; apices of branches abscised, elongation of the branch by the terminal apical lateral bud |
| 17' | Scaled resting buds absent (or weakly developed) and apical bud persistent |
| 18 | Pistillate inflorescences globose-capitate; stigma 1; tepals of the staminate flower valvate |
| 18' | Pistillate inflorescences spicate to subcapitate; stigmas 2; tepals of the staminate flower imbricate |
| 19 | Staminate material |
| 19' | Pistillate material |
| 20 | Stamen 1, straight in the bud. |
| 20' | Stamens 3, 4, or 5, inflexed in the bud |
| 21 | Stipules lateral; heads globose to obovoid; perianth 2-lobed to subentire |
| 21' | Stipules fully amplexicaul or, if lateral, then heads usually distinctly longer than wide and perianth 2-4-lobed to parted |
| 22 | Inflorescences spicate, all flowers sessile |
| 22' | Inflorescences racemose or cymose or subcapitate, all or some of the flowers pedicellate |
| 23 | Tepals valvate |
| 23' | Tepals imbricate |
| 24 | Midrib of the lamina impressed above; stamens 4 |
| 24' | Midrib of the lamina prominent above; stamens 3 (or 4) (T. scandens) |
| 25 | Bracts basally attached |
| 25' | Bracts (partly) peltate |
| 26 | Midrib prominent above (T. philippinensis) |
| 26' | Midrib impressed above |
| 27 | Inflorescences cymosely branched |
| 27' | Inflorescences unbranched |
| 28 | Flowers connate |
| 28' | Flowers free |
| 29 | Tepals free |
| 29' | Tepals connate |
| 30 | Stigma 1 |
| 30' | Stigmas 2 |
| 31 | Perianth fleshy in fruit; ovary adnate to the perianth, or if not, then the plant scandent |
| 31' | Perianth membranaceous in fruit; fruit free and the plant a shrub |
