1	Flowers bisexual		(2)
+	Flowers unisexual, plants monoecious or sometimes dioecious; perigone absent		(11)
2 (1)	Flowers with perianth ("perigone")		(3)
+	Flowers without perianth ("perigone") or reduced and not visible from above		(6)
3 (2)	Plants climbing		(4)
+	Plants herbaceous, not climbing		(5)
4 (3)	Ovary 3-loculed (but fruit monomerous); flowers functionally bisexual.		2 Pothos
+	Ovary 1-loculed; flowers functionally unisexual (plants dioecious).		3 Pothoidium
5 (3)	Plants without prickles (unarmored); leaves deciduous, oblong-cordate; inflorescences carried at ground level with most of peduncle hypogeal; plants of boreal habitats.		1 Symplocarpus
+	Plants armored with prickles; leaves evergreen, sagittate or hastate to pinnatifid or pinnatipartite; inflorescence carried on an erect, aerial peduncle; plants of tropical habitats.		9 Lasia
6 (2)	Plants aquatic and/or helophytic; spathe persistent; fruit red; plants of boreal habitats.		10 Calla
+	Plants climbing, not aquatic and/or helophytic; spathe deciduous; fruit various, if red then spathe caducous; plants of tropical habitats		(7)
7 (6)	Fruit each a discrete indehiscent berry		(8)
+	Fruit not a discrete berry, dehiscent via shedding of stylar plate		(9)
8 (7)	Inflorescences solitary or at most 3 held loosely together; flowers without perigone; fruit ovoid, white at maturity.		5 Amydrium
+	Inflorescences several together distichously arranged; flowers with reduced inconspicuous perigone; fruit truncate, red at maturity.		4 Anadendrum
9 (7)	Fruit each with numerous small, straight seeds.		6 Rhaphidophora
+	Fruit each with 1 to few large, curved seeds		(10)
10 (9)	Seeds 2-4 per fruit on an intrusive parietal placenta; leaves pinnately divided with pinholes along midrib.		7 Epipremnum
+	Seed 1 per fruit on a basal placenta; leaves always entire.		8 Scindapsus
11 (1)	Plant a free-floating aquatic.		26 Pistia
+	Plant never a free-floating aquatic, if aquatic then rooted in soil		(12)
12 (11)	Suffruticose herbs; fruit a red berry.		15 Aglaonema
+	Herbaceous plants of various life forms but never suffruticose; fruit various		(13)
13 (12)	Rooted aquatics; female flowers connate; fruit an apically dehiscent syncarpium.		13 Cryptocoryne
+	Terrestrial herbs and/or geophytes; female flowers free; fruit separate, indehiscent		(14)
14 (13)	Stamens of each male flower entirely connate into distinct synandrium		(15)
+	Stamens of each male flower free, or only filaments connate (rarely also anthers fused in Arisaema)		(19)
15 (14)	Spathe not differentiated into a distal limb and proximal tube		(16)
+	Spathe differentiated into a distal limb and proximal tube separated by a pronounced constriction		(17)
16 (15)	Spathe brightly colored (inside commonly yellow or purple-red); female flowers with staminodes (staminodes absent in S. griffithii); stem a repent or suberect epigeal rhizome.		22 Steudnera
+	Spathe white; female flowers without staminodes; stem a hypogeal tuber or stolon.		14 Hapaline
17 (15)	Plant with conspicuous erect aerial stolons bearing numerous barbed bulbils.		23 Remusatia
+	Plant without conspicuous erect aerial stolons, if stolons present then these decumbent and bearing tubercles at tips		(18)
18 (17)	Mature infructescences declined to pendent; placentation parietal; fruit < 3 mm (to 5 mm in C. gigantea), pale yellow to brown and fruit-smelling when ripe; seeds small, very numerous per fruit.		24 Colocasia
+	Mature infructescences erect; placentation basal; fruit > 4 mm, red when ripe, odorless; seeds large, few per fruit.		25 Alocasia
19 (14)	Spadix appendix absent (spadix fertile to apex), or if present then usually consisting of clearly defined subglobose sterile (neuter) flowers		(20)
+	Spadix appendix present, ± smooth to rugulose, hairy or echinate, without subglobose sterile (neuter) flowers, or if such sterile flowers present then usually confined to proximal part or base		(21)
20 (19)	Spathe wholly persistent into fruiting, splitting from base to apex at fruit maturity; spathe free from spadix; spadix appendix absent; vegetative tissues aromatic (terpenoids) when crushed.		11 Homalomena
+	Spathe limb deciduous during anthesis, proximal spathe persisting to fruiting and then splitting from apex to base at fruit maturity; much of female zone of spadix adnate to spathe; spadix appendix present; vegetative tissues not aromatic.		12 Schismatoglottis
21 (19)	Spadix unisexual, or if bisexual then male and female zones contiguous or separated by sterile zone usually covered with staminodes		(22)
+	Spadix bisexual, male and female zones separated by naked sterile axis (interstice)		(23)
22 (21)	Leaves variously divided (most commonly pedate to pedatisect but not decompound), very rarely entire; berries ripening reddish.		21 Arisaema
+	Leaves commonly solitary, usually decompound, very rarely pedate, never entire; berries ripening red or blue.		16 Amorphophallus
23 (21)	Female zone of spadix adnate to spathe.		20 Pinellia
+	Female zone of spadix free		(24)
24 (23)	Appendix with a whorl of prominent staminodes directly above male zone; placentation parietal.		17 Arum
+	Appendix with a stipelike smooth part below base or contiguous with male zone, whorl of staminodes absent above male zone; placentation basal		(25)
25 (24)	Sterile zone between female and male zones with smooth naked distal part, base with various numbers of staminodes or whole zone covered with staminodes but then leaves always entire and proximal staminodes spatulate (in T. flagelliforme).		18 Typhonium
+	Sterile zone between female and male zones fully covered with staminodes, or grooved and with staminodes only at base; leaves usually pedate, rarely entire (in S. giganteum); staminodes never spatulate		19 Sauromatum