| 1 | Erect trees or shrubs. |
| 1' | Lianas. |
| 2 | Leaves simple, mostly in whorls |
| 2' | Leaves compound, almost always decussate. |
| 3 | Leaves 1-pinnate. |
| 3' | Leaves 2-3(-4)-pinnate. |
| 4 | Leaf rachis with a sharp, keel-like ridge above. Leaflets 8-12 pairs. Capsules winged |
| 4' | Leaf rachis not keeled above. Leaflets less than 6 pairs. Capsules not winged. |
| 5 | Corolla salver-shaped, white, nocturnal, the tube 12-18 cm long, narrow-cylindric. Calyx spathaceous to the base, 3-6 cm. Leaves nigrescent, with domatia. A flat pseudoseptum developed parallel to the valves. Seeds rectangular, with corky wings as thick as the seed. |
| 5' | Corolla much shorter. No pseudoseptum. Seeds with hyaline wings. Leaves not nigrescent. |
| 6 | Mature leaflets serrate, crenate, or pinnatifid |
| 6' | Mature leaflets entire. |
| 7 | Calyx regularly 5-lobed, rather thin, reticulately veined, short-hairy, 2-3 cm |
| 7' | Calyx lobes unequal, often less than 5; calyx not thin and reticulate-veined. |
| 8 | Capsule rather flattened, with a flat septum, if terete with 10 ribs /. |
| 8' | Capsule terete, with a terete septum, never with many ribs, sometimes one ridge on each valve. No domatia in Mal. spp. |
| 9 | Seeds thick, in one row in each cell, each fitting in deep notch in the septum. Valves rather hard. Ovules in 2 rows in each cell |
| 9' | Seeds thick, in many rows, the septum without notches. Valves thin. Ovules in many rows in each cell |
| 10 | Flowers fleshy, very coarse: calyx 2-4 cm, corolla wide, dirty violet or reddish purple to liver brown, 7-10 cm. Capsule flat, sword-shaped, 60-120 cm |
| 10' | Flowers not fleshy, much smaller or thinner, white or pink. Capsule smaller and of different shape. |
| 11 | Leaflets with domatia. Corolla white, salver-shaped, the tube 6-8 cm long, cylindric, 2 mm wide. Capsule compressed parallel to the septum, the latter parallel to the valves; dehiscence septicidal. |
| 11' | Leaflets without domatia. Corolla tube otherwise, wider. Capsule cylindric, with a terete corky septum attached perpendicular to the valves; dehiscence loculicidal |
| 12 | Corolla salver-shaped, with a narrow cylindric tube, 5-19 cm long. Capsule flat, large, with a median lengthwise ridge. Septum parallel to the valves, dehiscence loculicid. |
| 12' | Corolla not salver-shaped, tubular, infundibuliform or funnel-shaped. |
| 13 | Corolla tube ± geniculate above the basal tube, upper tube slightly curved and flattened with a prominent fold. Calyx c. ½ cm, below the very short lobes with a short spur-like tooth. Ovules 6-8 per cell, in ± two rows. Leaflets 5, those of the lower pair sessile |
| 13' | Corolla tube not geniculate, without a fold. Ovules per cell in several rows. Capsule loculicid, with boat-shaped valves. |
| 14 | Leaves digitate, with 3(-5) leaflets. Corolla lobes valvate |
| 14' | Leaves pinnate, with 1 or more pairs of leaflets. Corolla lobes imbricate. |
| 15 | Flowers in racemes, axillary, mostly on the old wood, rarely terminal (in a high-mountain sp.), the rachis at the base usually with several crowded pairs of minute sterile bracts. Calyx large, 15-40 mm, distinctly lobed. Corolla large, mostly red, 5-12 cm long incl. the lobes, not bearded in the mouth and upper part of the tube, but stuppose hairy at the insertion of the stamens (rim of the basal tube). Corolla lobes usually deltoid, very narrowly overlapping. Anther-cells 4-5(-10) mm long |
| 15' | Flowers in thyrses, only occasionally depauperate into racemes, usually terminal, sometimes axillary or on old wood. No sterile bracts at base of peduncle. Calyx small, mostly stunted or very shortly lobed, 2-7 mm. Corolla incl. lobes up to c. 3½ cm (in a single Australian species with large lobes c. 5 cm), usually white or yellowish with red dots or streaks inside lobes and mouth, often bearded in the mouth and upper part of the tube, sometimes with a hair-ring at the insertion of the anthers. Corolla lobes widely overlapping, often roundish. Anther-cells 1½- 2 mm long |
