1	"Perianth 0 or of 1 whorl, generally called sepals even when petal-like"	2
1	"Perianth of 2 or more whorls or spirals, the outer generally called sepals, the inner generally called petals"	8
2	"Hypanthium present"	Rosaceae
2	"Hypanthium 0"	3
3	"Trees; leaves palmately lobed"	"Platanaceae {Platanus}"
3	"Herbs or woody vines; leaves various"	4
4	"Plant terrestrial or if aquatic with emergent leaves"	Ranunculaceae
4	"Plant aquatic with submersed or floating leaves"	5
5	"Perianth parts 1--4"	6
5	"Perianth +- 0"	7
6	"Perianth part 1, white, petal-like, enlarging and turning green in age; stamens 6--18; fruit follicle, 4-seeded"	"Aponogetonaceae {Aponogeton distachyos}"
6	"Perianth parts 4, green or +- brown, sepal-like; stamens 4; fruit achene-like drupe, 1-seeded"	Potamogetonaceae
7	"Flowers bisexual, borne along axis of initially short-peduncled spike, peduncle elongating in fruit; stamens 2; pistils (2)4(8); ovary stalk in fruit 12--35 mm; fruit +- ovoid, smooth, beak 0.5--1 mm"	"Ruppiaceae {Ruppia}"
7	"Flowers unisexual, staminate and pistillate together in sessile, 2-flowered axillary cluster; stamen 1; pistils (1)4--5(9); ovary stalk in fruit 0.1--1.5 mm; fruit abaxially curved, minutely roughened, beak 0.7--2 mm"	"Zannichelliaceae {Zannichellia palustris}"
8	"Leaves and often stems thick and fleshy; pistils generally as many as petals or sepals --- stamens 1--2 × as many"	Crassulaceae
8	"Leaves and stems not very thick and fleshy; number of pistils same as or different from number of sepals or petals"	9
9	"Perianth parts in 3s"	10
9	"Perianth parts generally in 4s or 5s or indefinite in number"	16
10	"Leaves compound"	11
10	"Leaves simple"	12
11	"Tree with unbranched trunk; leaves 4--7 m, leaflets many"	"Arecaceae {Phoenix}"
11	"Annual; leaves <= 6 cm, leaflets 3--5 --- carpels actually united by common style"	"Limnanthaceae {Floerkea}"
12	"Flowers solitary --- sepals and petals all similar, +- white or +- red-purple; leaves floating and peltate or some or all submersed and dissected"	Cabombaceae
12	"Flowers several--many in raceme- to panicle-like inflorescence"	13
13	"Sepals green, petals white (pink)"	Alismataceae
13	"Sepals and petals the same color, +- white to green or +- red"	14
14	"Inflorescence bractless --- carpels actually +- fused, separating in fruit"	"Juncaginaceae {Triglochin}"
14	"Inflorescence bracted"	15
15	"Ovules many per carpel; fruits erect --- carpels actually proximally fused [may appear +- free]"	Melanthiaceae
15	"Ovules 1--3 per carpel; fruits spreading"	"Scheuchzeriaceae {Scheuchzeria palustris}"
16	"Stamens > 2 &times; as many as petal-like perianth segments or > 15"	17
16	"Stamens 2 &times; as many as petals or fewer"	23
17	"Plants obviously woody; shrubs or trees"	18
17	"Plants herbaceous or slightly woody at base"	20
18	"Crushed leaves strongly aromatic; leaves opposite"	"Calycanthaceae {Calycanthus occidentalis}"
18	"Crushed leaves not aromatic; leaves alternate"	19
19	"Flowers solitary; seeds with arils"	Crossosomataceae
19	"Flowers clustered; seeds without arils"	Rosaceae
20	"Hypanthium present"	Rosaceae
20	"Hypanthium 0"	21
21	"Sepals enlarging and persisting around fruit; stamens maturing from flower center toward edge"	"Paeoniaceae {Paeonia}"
21	"Sepals deciduous as flower opens or withering as fruit matures; stamens maturing from flower edge toward center"	22
22	"Sepals 2--3(4), falling as flower opens, not petal-like; carpels actually weakly fused in flower, +- separating in age"	"Papaveraceae {Platystemon}"
22	"Sepals 4--many, present in open flowers, sometimes petal-like; carpels generally wholly free"	Ranunculaceae
23	"Petals fused, at least at base"	24
23	"Petals free but sometimes attached to a disk-like to tubular hypanthium"	25
24	"Plant erect, prostrate, or twining; flowers generally conspicuous, not concealed by leaves; ovules many per ovary; milky latex generally present --- carpels proximally free but actually united by common stigma"	Apocynaceae
24	"Plant prostrate, mat-forming; flowers minute, subsessile, axillary, generally concealed by leaves; ovules 1--2 per ovary; milky latex 0"	"Convolvulaceae {Dichondra}"
25	"Hypanthium well developed"	26
25	"Hypanthium 0 or inconspicuous"	28
26	"Leaves simple, basal or cauline; stipules often 0; veins generally palmate; ovules generally several--many per carpel --- carpels slightly fused proximally but free most of their length"	Saxifragaceae
26	"Leaves simple or compound, generally cauline; stipules generally present; veins often pinnate; ovules generally 1--2 per carpel"	27
27	Shrub	"Crossosomataceae {Glossopetalon spinescens var. aridum}"
27	Herb	Rosaceae
28	"Plant herbaceous"	29
28	"Plant woody"	30
29	"Annual; ovule 1 per ovary; leaves pinnately divided or compound --- carpels actually united by common style"	"Limnanthaceae {Limnanthes}"
29	"Perennial herb; ovules several--many per ovary; leaves simple and entire or variously toothed to palmately lobed or compound"	Saxifragaceae
30	"Leaves pinnately compound"	"Simaroubaceae {Ailanthus}"
30	"Leaves simple, entire, sometimes scale-like"	31
31	"Flowers solitary in leaf axils; fruit a cluster of follicles; leaves elliptic, persistent or drought-deciduous"	Crossosomataceae
31	"Flowers in dense panicles; fruit cluster of +- dry drupes; leaves scale-like to narrowly oblong, early-deciduous --- shrub with thorny green stems"	"Simaroubaceae {Castela}"