| 1 | Leaf blade distinctly peltate; inflorescence axillary (but in fact on a terminal, reduced leafless shoot), umbel-like |
| 1' | Leaf blades basely attached; inflorescences leaf-opposed, simple |
| 2 | Leaves palmately veined or palmately-pinnately veined with secondary veins originating from the lower 1/4 of the primary vein |
| 2' | Leaves pinnately veined, i.e. secondary veins originating from the lower 1/3 to throughout the primary vein |
| 3 | Veins originating from the base and 1 or 2 branching off the lower 1/4 of the primary vein |
| 3' | Veins all originating from the base |
| 4 | Leaf base acute; cultivated |
| 4' | Leaf base rounded to cordate; in natural habitats |
| 5 | Primary veins 9-11, leaf base deeply cordate, margin ciliate |
| 5' | Primary veins 5-7(-9), leaf base acute or rounded to subcordate, margin not ciliate |
| 6 | Stem without spines; tertiary venation obscure |
| 6' | Stem often with spines opposite petiole; tertiary venation prominent below |
| 7 | Leaf blades less than 3 cm wide |
| 7' | Leaf blades more than 3 cm wide |
| 8 | Leaf base rounded to subcordate |
| 8' | Leaf base obtuse to acute |
| 9 | Secondary veins 2-5 per side, originating from the lower 1/2 of the primary vein; floral bracts densely marginally fringed |
| 9' | Secondary veins 6-15 per side, originating throughout the primary vein; floral bracts glabrous |
| 10 | Stem glabrous; leaf blade not scabrous above; secondary veins 2-3 per side; reported from high elevation |
| 10' | Stem villous; secondary veins ca. 5 per side; leaf blade somewhat scabrous above; known only from type collection, not from high elevation |
| 11 | Stem retrosely pubescent; secondary veins 6-10 per side |
| 11' | Stem glabrous except for subnodal lines of hairs; secondary veins 8 or more per side |
| 12 | Leaf blade 3-4 x as long as wide, apex acute to shortly acuminate; secondary veins 8-12 per side |
| 12' | Leaf blade 4-6 x as long as wide, apex long-acuminate; secondary veins 8-15 per side |
| 13 | Leaf blades 14-35 cm wide, deeply lobed at base |
| 13' | Leaf blades less than 14 cm wide, or if wider then not distinctly lobed |
| 14 | Fruits puberulent at apex |
| 14' | Fruits subglabrous |
| 15 | Stems and leaves glabrous, but leaf margins ciliate |
| 15' | Another combination of characters for stems, leaves and margins |
| 16 | Secondary veins 10-16, originating throughout the primary vein |
| 16' | Secondary veins 4-6, originating from the lower 1/2 of the primary vein |
| 17 | Whole plant densely dark glandular dotted; stem glabrous; leaves sparsely villous on both sides |
| 17' | Plants not dark glandular dotted; stems with subnodal lines of hairs or glabrous or variously pubescent; leaves glabrous or variously pubescent |
| 18 | Stems with subnodal lines of hairs |
| 18' | Stems glabrous or variously pubescent |
| 19 | Leaf blade glabrous below |
| 19' | Leaf blade pubescent below |
| 20 | Leaf base very unequally attached to petiole, difference 0.5-1(-3) cm |
| 20' | Leaf base equal or slightly unequally attached to petiole, to less than 0.5 cm |
| 21 | Petiole without stalked glands (tubercles); leaf apex acute or acuminate |
| 21' | Petiole with stalked glands (tubercles); leaf apex obtuse, rounded or slightly acute |
| 22 | Leaf blades — at least the veins — variously pubescent |
| 22' | Leaf blades glabrescent or glabrous on both sides |
| 23 | Leaf blades pubescent on both sides — at least on the veins — and/or blades scabrous |
| 23' | Leaf blades glabrous above, pubescent below — at least on the veins — blades never scabrous |
| 24 | Leaf blades scabrous, at least above |
| 24' | Leaf blades not or hardly scabrous |
| 25 | Spike distinctly curved |
| 25' | Spikes straight, not curved |
| 26 | Secondary veins originating from the lower 1/3 of the primary vein; veins strongly prominent below; savanna shrub |
| 26' | Secondary veins originating throughout or from the lower 1/2 of the primary vein; veins at most prominent below; in forest or secondary vegetation |
| 27 | Petiole and peduncle 1.5-2 cm long; leaf blade broadly ovate |
| 27' | Petioles and peduncles less than 1.5 cm long; leaf blades lanceolate-oblong, elliptic to ovate or rhombic |
| 28 | Herb or subshrub, 0.15-1.5 m tall; secondary veins originating throughout the primary vein |
| 28' | Shrubs or treelets, 2-5 m tall, occasionally with scrambling branches; secondary veins originating from the lower 1/2 of the primary vein |
| 29 | Prophyll densely pubescent; leaf blade rhombic to subobovate; spike 7-8 cm long; anthers dehiscing laterally; fruits glabrous with some hairs at top |
| 29' | Prophyll glabrous; leaf blade elliptic or elliptic-ovate; spike 8-14 cm long; anthers dehiscing transversely apically; fruits hirsute |
| 30 | Spikes erect |
| 30' | Spikes pendent |
| 31 | Peduncle (filiform) much longer than the spike; spike 1-1.7 cm long |
| 31' | Peduncle (not filiform) shorter than the spike; spike 7-20 cm long |
| 32 | Petioles 0.5-1.5 cm long; spikes 7-8 cm long; leaf blade elliptic, rhombic or subobovate |
| 32' | Petioles 1.5-2 cm long; spikes 10-20 cm long; leaf blade broadly ovate |
| 33 | Leaf blade margin hardly ciliate, base almost equally attached to petiole; floral bracts cucullate, pilose at inner side |
| 33' | Leaf blade margin ciliate, base unequally attached to petiole difference 0-0.8 cm; floral bracts not cucullate, marginally fringed |
| 34 | Stem pilose with 2 mm long hairs; internodes drying finely ridged |
| 34' | Stem hirsute with 2.5 mm long hairs; internodes not ridged |
| 35 | Leaf apex obtuse or acutish |
| 35' | Leaf apices acute to long-acuminate |
| 36 | Leaf blade slightly bullate |
| 36' | Leaf blades smooth |
| 37 | Peduncle (filiform) much longer than the spike; leaf base equally attached to the petiole; secondary veins 4-5(-7) per side, at base originating with 2 pairs |
| 37' | Peduncle (stout) as long as or far shorter than the spike; without above given combination of characters |
| 38 | Scandant or creeping shrub; floral bracts densely marginally fringed; spike conspicuously protandrous, conical in male stage, stamens long exserted |
| 38' | Herbs, shrubs or treelets; floral bracts glabrous or variously pubescent or fringed; spikes in male stage cylindrical, stamens short |
| 39 | Floral bracts cucullate, glabrous or sparsely pilose |
| 39' | Floral bracts trigonous or rounded-trigonous, densely marginally fringed |
| 40 | Low herb or subshrub, sometimes creeping; secondary veins conspicuously anastomosing |
| 40' | Shrubs, never creeping; secondary veins not conspicuously anastomosing |
| 41 | Secondary veins 5-7 per side, originating from the lower 2/3 of the primary vein |
| 41' | Secondary veins 7-12 per side, originating throughout the primary vein |
| 42 | Leaf base subcordate, obtusish, rounded, or cuneate, not lobed |
| 42' | Leaf base unequally cordate, with one lobe more or less covering the petiole |
| 43 | Spike pendent, 1-1.5 cm, in fruit 2.5 cm long; ovary and fruit stylose |
| 43' | Spike erect, 3.5-4.5 cm long; ovary and fruit not stylose |
| 44 | Spikes pendent |
| 44' | Spikes erect |
| 45 | Petiole 2.5-4.5(-7.5) cm long; leaf base strongly asymmetrical; secondary veins widely spaced |
| 45' | Petiole 0.2-1.3 cm long; leaf base unequal; secondary veins not widely spaced |
| 46 | Indument of spreading, to 0.5 mm long, hairs; leaf apex long-acuminate; fruits distinctly separate at maturity, 2.5-4 mm in diam. |
| 46' | Indument of short crisp, to 0.2 mm long, hairs; leaf apex short-acuminate or acute; fruits not distinctly separate, to 2 mm in diam. |
| 47 | Petiole conspicuously winged; leaf blade hirsute below |
| 47' | Petioles at most vaginate; leaf blades variously pubescent below |
| 48 | Leaf blades crisp- to erect-pubescent below |
| 48' | Leaf blades appressed pubescent below |
| 49 | Leaf base acute to cuneate |
| 49' | Leaf base obtuse, rounded or subcordate |
| 50 | Leaf apex acute; fruits glabrous |
| 50' | Leaf apex long-acuminate; fruits hirsute |
| 51 | Secondary veins originating at an angle of 60o and abruptly curving upwards at an angle of 120o, well within the margin |
| 51' | Secondary venation not as above |
| 52 | Petiole 0.3-1 cm long; leaf blade somewhat scabrous and somewhat bullate; peduncle crisp-pubescent |
| 52' | Petioles 0.5-6.5 cm long; leaf blade not scabrous, nor bullate; peduncle glabrous |
| 53 | Stipules about as long as petiole; leaf blade broadly ovate, not conspicuously glandular dotted below |
| 53' | Stipules longer than petiole; leaf blade elliptic-ovate, densely glandular-dotted below |
| 54 | Fruits with 4 apical projections or fruits distinctly winged, ridged or sulcate |
| 54' | Fruits without 4 apical projections, not distinctly winged nor ridged nor sulcate |
| 55 | Fruits with 4 prominent apical projections |
| 55' | Fruits distinctly winged, ridged or sulcate |
| 56 | Infructescence 2.5-4.5 cm long, fruits distinctly sulcate |
| 56' | Infructescence 10-12 cm long, fruits ridged or winged. |
| 57 | Ovaries and fruits distinctly stylose |
| 57' | Ovaries and fruits with sessile stigmas, occasionally with inconspicuous short style |
| 58 | Leaf blade not conspicuously glandular; spike 12-15 cm long |
| 58' | Leaf blade densely conspicuously glandular; spike 2-4 cm long |
| 59 | Climbing or creeping herb; leaf base cordate or obtuse; flowers protandrous or unisexual, stamens long exserted |
| 59' | Subshrubs, shrubs or treelets; leaf base acute, obtuse or rounded; flowers bisexual, stamens short, not exserted |
| 60 | Leaf base unequally attached to the petiole difference 0.5-1 cm |
| 60' | Leaf bases less unequal, difference at the petiole less than 0.5 cm |
| 61 | Floral bracts not marginally fringed, glabrous or at most somewhat pilose |
| 61' | Floral bracts densely marginally fringed |
| 62 | Spike pendent, 1 cm long |
| 62' | Spikes erect, to 7 cm long |
| 63 | Petiole up to 3.2 cm long; leaf blade more than 7 cm wide; secondary veins from lower 2/3 of primary vein |
| 63' | Petiole up to 2 cm long; leaf blade less than 6.5 cm wide; secondary veins originating from throughout primary vein |
| 64 | Leaf blades asymmetrical, i.e. one half wider and more obtuse at least below the middle |
| 64' | Leaf blades symmetrical |
| 65 | Spike erect, to 10 cm long; veins often drying yellowish |
| 65' | Spikes pendent, to 6 cm long; veins not drying yellowish |
| 66 | Petiole 1-2.2 cm long; leaf blade dark glandular-dotted; peduncle 0.5-1.5 cm long |
| 66' | Petiole 2.5-4.5(-7.5) cm long; leaf blade not conspicuously glandular-dotted; peduncle 1.5-2.5 cm long |
| 67 | Leaf base acute, cuneate or obtusish |
| 67' | Leaf base truncate, obtuse or rounded |
| 68 | Secondary veins originating from lower 1/2 to lower 2/3 of primary vein; peduncle up to 3 cm long, spikes 5-9 cm long |
| 68' | Secondary veins originating from lower 3/4 or throughout primary vein; peduncle up to 2 cm long, spikes 1-5 cm long |
| 69 | Leaf blade conspicuously glandular-dotted; secondary veins 4-6 per side |
| 69' | Leaf blade not conspicuously glandular-dotted; secondary veins 3-4 per side |
| 70 | Petiole 1-2 cm long; spike erect; fruits puberulent |
| 70' | Petiole 0.4-0.8 cm long; spike pendent; fruits glabrous |
| 71 | Spike 1-1.7 cm long |
| 71' | Spikes 7-11 cm long |
| 72 | Stipules about as long as petiole; leaf blade broadly ovate, base truncate to cordulate, not conspicuously glandular-dotted below |
| 72' | Stipules longer than petiole; leaf blade elliptic-ovate, base obtuse to rounded, densely glandular-dotted below |
