| 1 | Leaves < 0.8 cm long, often reduced to scale-leaves, or apparently absent |
| 1' | Leaves foliaceous, more than 1 cm long |
| 2 | Small, erect plants with terete internodes 2-3 cm long; basal and intercalary cataphylls absent; fruiting perianth segments closed |
| 2' | Pendent plants with compressed internodes 3-9 cm long; basal and intercalary cataphylls 1 pair each, tubular; fruiting perianth segments erect |
| 3 | Plants dichotomous, either through terminal inflorescences or through abortion of apex |
| 3' | Plants percurrent (not dichotomous) |
| 4 | Flowers 3 per fertile bract, the terminal male, lateral ones female; leaves obscurely 3-veined; percurrent portions with 1 pair of intercalary cataphylls |
| 4' | Not the above sex distribution; leaves not obscurely 3-veined; percurrent shoots normally absent |
| 5 | Leaf blade mostly lanceolate and acute at both ends |
| 5' | Leaf blade obovate, the apex broadly rounded |
| 6 | Flowers 1-3 per fertile bract, the male usually few and on lowest fertile internode; fruiting perianth segments erect or parted |
| 6' | Flowers 5-9 per fertile bract, the single male highest above bract; fruiting perianth segments closed |
| 7 | Leaf blade to 6 x 3.5 cm, more or less leathery, venation obscure |
| 7' | Leaf blade to 13 x 10 cm, thin, venation evident |
| 8 | Intercalary cataphylls present; terminal inflorescences lacking |
| 8' | Intercalary cataphylls absent |
| 9 | At least some intercalary cataphylls subtending inflorescences |
| 9' | Intercalary cataphylls present but not subtending inflorescences |
| 10 | Peduncle simple or very unequally double; fertile internodes mostly 4; male flowers below female ones on each fertile internode; fruiting perianth segments closed |
| 10' | Peduncle with 2 or more short and crowded sterile internodes, female flowers below (apical) male one in each flower area; fertile internodes 5-9; fruiting perianth segments more or less erect |
| 11 | Plants golden green; young internodes sharply keeled; leaves with 3 or 5 palmate veins; flowers 3-seriate |
| 11' | Plants not golden green; internodes terete; venation pinnate; flowers mostly 2-seriate |
| 12 | Flowers 3 per fertile bract, apical one male, lateral ones female; fruit tuberculate |
| 12' | Not the above flower number; male flowers in various positions, or plants dioecious; fruits smooth |
| 13 | Leaves with 3(5) basal veins, round-tipped; internodes quadrangular; flowers 2-seriate |
| 13' | Leaves with more than 3 basal veins, or venation pinnate, apex rounded to acute; internodes and flower seriation various |
| 14 | Fruiting perianth segments closed when mature, fruit yellow |
| 14' | Fruiting perianth segments erect when mature, fruit reddish orange |
| 15 | Internodes keeled to quadrangular below |
| 15' | Internodes terete at least below |
| 16 | Leaf apex acute or at least tapering; internodes keeled but not usually quadrangular or winged |
| 16' | Leaf apex somewhat tapering or rounded but not ultimately acute; internodes keeled to quadrangular or even winged |
| 17 | Leaf blade broadest below middle; plants monoecious; most fertile internodes with 5 flowers per fertile bract |
| 17' | Leaf blade broadest at middle; plants dioecious; flowers 1 or 3 per fertile bract, at least in female |
| 18 | Female flowers 3 per fertile bract; fertile internodes 2 or 3; fruit placed on middle of fertile internode; fruiting perianth segments somewhat parted to erect; known from Suriname only |
| 18' | Female flowers 1 per fertile bract; fertile internodes 5-8; fruit placed distally on fertile internode; fruiting perianth segments closed; known from French Guiana only |
| 19 | Flowers 2-seriate |
| 19' | Flowers 3-seriate or 3 per fertile bract |
| 20 | Leaves obovate, of varnished appearance; inflorescence peduncle with 2-4 (-10) sterile internodes |
| 20' | Leaves lanceolate, not of varnished appearance; inflorescence peduncle simple |
| 21 | Flowers 2-seriate, more than 3 per fertile bract |
| 21' | Flowers 3-seriate, no more than 3 per fertile bract |
| 22 | Leaves coriaceous, venation completely obscure except for midrib |
| 22' | Leaves not coriaceous, with evident venation |
| 23 | Flowers and (especially) fruits sunken in cavities in inflorescence axis; plants usually blackening when dry |
| 23' | Flowers or fruits not sunken in cavities; plants not blackening usually |
| 24 | Fruits placed very high on fertile internodes, 3 per fertile bract; fruiting perianth segments large, flaring |
| 24' | Fruits distributed along fertile internodes, mostly > 3 per fertile bract (except female P. pellucidulum); fruiting perianth segments relatively small, closed |
| 25 | Venation lacking strong basal, lateral veins; lower midrib usually lightly scurfy |
| 25' | Venation palmate or pinnate with strong, basal lateral veins; lower midrib smooth, not scurfy |
| 26 | Young leaves thin, translucent red; inflorescence with 3(4) fertile internodes; mostly dioecious; fruit no more than 3 per fertile bract; placed high on fertile internode |
| 26' | Young leaves neither thin nor translucent red; inflorescence 4-10 or more fertile internodes; monoecious or dioecious; fruit mostly > 3 per fertile bract, spread along fertile internode |
| 27 | Normally hyperparasitic on other mistletoes; dioecious; internodes tending to be quadrangular to 4-winged; fruit 0.2 x 0.2 cm |
| 27' | Not hyperparasitic; monoecious; internodes no more than slightly keeled above; fruit 0.4 x 0.3 cm |
| 28 | Perhaps exclusively hyperparasitic on other mistletoes; petiole often broad, flat, blade somewhat amplexicaul |
| 28' | Not hyperparasitic; petiole not flat, blade not amplexicaul |
| 29 | Young leaves translucent red; inflorescence with 3(4) fertile internodes; fruits no more than 3 per fertile internode, placed high on fertile internode |
| 29' | Young leaves neither thin nor translucent red; inflorescence with 6-10 or more fertile internodes; fruits mostly > 3 per fertile bract, spread along fertile internode |
