Key to the species of Decaisnina

1Inflorescence subtended by an involucre of decussate scales at the base of the axis
1'Inflorescence not subtended by an involucre of decussate scales at the base of the axis
2Inflorescence axis oriented vertically with the flowers not strongly secund; lateral flowers of the triads on distinct pedicels at least as long as the ovary
2'Inflorescence axis oriented horizontally with the flowers strongly secund, giving the inflorescence a brush-like appearance; lateral flowers of the triads on obscure pedicels much shorter than the ovary
3Stems and inflorescence parts very thick; internodes short and often crowded so that the leaves appear verticillate; corolla more than 30 mm long..
3'Stems and inflorescence parts slender to moderately robust; internodes normally developed with evenly spaced decussate leaf pairs; corolla less than 30 mm long
4Inflorescence axis less than 15 mm long; corolla 5-merous, hardly inflated at the base
4'Inflorescence axis more than 30 mm long; corolla 6-merous, distinctly inflated at the base
5Leaf lamina up to 8 cm long; triads crowded at the end of the inflorescence axis..
5'Leaf lamina more than 10 cm long; triads distributed uniformly along the inflorescence axis
6Anthers sessile or nearly so, with free filament less than 1 mm long
6'Anthers on distinct free filaments at least 2 mm long
7Corolla less than 10 mm long
7'Corolla 10-24 mm long
7''Corolla more than 24 mm long
8Young internodes 4-angular; leaf lamina glossy on both sides, darker above, recurved at the margin; inflorescence and flowers shortly and densely tomentose..
8'Young internodes dilated and 2-angled in the upper part; leaf lamina dull on both sides, not recurved at the margin; inflorescence and flowers glabrous or sparsely hairy
9Triads in 1-3 pairs crowded near the apex of the inflorescence axis
9'Triads in several pairs distributed uniformly along much of the inflorescence axis
10Stems and inflorescence parts very thick; internodes short and often crowded so that the leaves appear verticillate; corolla inflated to 5 mm wide in the lower part
10'Stems and inflorescence parts slender to robust; internodes normally developed with evenly spaced decussate leaf pairs; corolla not or slightly inflated at the base.
11Leaf lamina acuminate acute at the apex; corolla 35-50 mm long.
11'Leaf lamina obtuse to rounded at the apex, often with a small blunt mucro; corolla 23-30 mm long
12Leaves with upper surface glossy or darker than the dull lower surface
12'Leaves dull and more or less the same colour on both sides
13Leaves sessile, truncate to amplexicaul at the base
13'Leaves petiolate, or if sessile attenuate at the base
14Petals eventually separating to the base; anthers transversely septate prior to anthesis
14'Petals remaining coherent in the lower part; anthers not transversely septate..
15Plant robust, usually with a short brown tomentum on the young parts and inflorescences; leaves with a distinct petiole mostly more than 10 mm long; corolla mostly more than 30 mm long
15'Plant relatively slender, glabrous or rarely with the inflorescence sparsely pubescent; leaves with a petiole mostly less than 10 mm long; corolla less than 30 mm long 18.
16Corolla inflated and globular at the base
16'Corolla not inflated at the base, or if so then not sharply contracted to form a globular dilation
17Young internodes strongly angular distally
17'Young internodes not strongly angular distally
18Corolla pale green or yellow in the lower part; petals separating to the base at anthesis
18'Corolla red in the lower part; petals cohering in the lower 1-15 mm after anthesis
19Triads with all flowers sessile
19'Triads with the central flower sessile and the lateral flowers pedicellate
20Leaf lamina broadly lanceolate to elliptic, attenuate at the base to an obscure petiole 3-5 mm long; corolla 23-30 mm long
20'Leaf lamina elliptic to almost orbicular, shortly cuneate at the base with a distinct petiole 25-40 mm long; corolla 30-50 mm long 11.